苏里格气田随着逐年开发,低压低产井越来越多.此类井产能较差,部分存在严重积液,排水采气工艺已在该区块广泛应用,但是各类工艺的参数优化,以及不同类型、不同时期产水气井对各种工艺的适用性如何,仍是急待解决的现实问题.该区块应用较多的是泡沫排水采气和井下工具类排水采气(速度管柱、雾化和涡流工具),本文对其工艺原理、工艺应用、工艺优化与适用性分析和室内及现场实验研究现状进行了综述,并提出了目前该领域研究需要关注和待解决的相关问题.

As a critical technical approach for shale reservoir development,dynamic imbibition displacement during the fractur-ing stage has emerged as a focal point in reservoir engineering research over recent years.In light of global energy demands and ongoing exploration of unconventional oil and gas resources,the significance of this technology in enhancing the exploitation of shale oil reservoirs cannot be overstated.However,the specific mechanisms of dynamic imbibition process in shale oil reservoirs influenced by various factors still aren't unclear,and it's difficult to accurately quantify their impact on imbibition oil production efficiency.These uncertainties significantly hinder further improvement in the development efficiency of shale oil reservoirs,lead to higher development costs and bring huge challenges to sustainable resource development. Aiming at the unclear dynamic imbibition mechanisms and action laws of shale oil reservoir,a core-scale numerical simulation model was established,and the control variable method was adopted to set up 15 simulation schemes.By these methods,the mechanisms of displacement pressure difference,capillary radius,wetting angle and oil-water viscosity of dynamic imbibition displacement effect,and the change laws of fluid seepage were revealed.The effects of displacement pressure difference,capillary radius,wetting angle,and oil-water viscosity on the effectiveness of dynamic imbibition oil recovery,and the laws of fluid seepage changes were clarified in this study.The results show that:During dynamic imbibition,as the capillary radius increase from 0.1 μm to 10 μm,capillary force decrease and fluid seepage rate accelerates,leading to 8.0%increase in imbibition recovery.Along with the displacing pressure difference increases from 0 MPa to 3 MPa,the imbibition upgrades from static to dynamic,and the imbibition recovery degree increases by 7.9%.It is considered that the displacing pressure difference and the recovery degree are in accordance with the power function relationship,and there is an optimal displacing pressure difference.With changes in rock wettability from hydrophilic to neutral or oleophilic,extraction degree decreases from 48.9%for water-wet conditions to 33.9%for oil-wet conditions.As crude oil viscosity decreases from 53.3 mPa·s to 13.99 mPa·s,imbibition recovery rate increases by 9.1%;the higher the viscosity of water phase,the smaller the initial imbibition velocity,but the better the imbibition displacement effect.In oil field operation,by optimizing injection pressure,selecting suitable fracturing fluid and surfactant,the hydrophilic degree and displacement phase viscosity can be improved,and the dynamic imbibition process can be improved to increase the oil displacement efficiency.In the future,the complexity of multiphase flows and the heterogeneity of reservoirs should be further considered to study the influence of various factors on the dynamic imbibition process of shale from different scales.

The lower Cambrian organic-rich shales are widely distributed in the middle-upper Yangtze platform,which are also the main target layers for shale gas exploration and extraction.Revealing the enrichment mechanisms of organic matter in these shales is of great significance for understanding the relationship between ocean bio-environmental systems and Earth resources.Through systematical geochemical analyses,this study investigated the lower Cambrian Niutitang Formation slope facies shales at the western Xuefeng Uplift,to elucidate the paleoenvironmental characteristics and their main controlling factors.The results show that the Niutitang Formation shales generally have high TOC contents,with higher TOC contents in the lower part than those in the upper part.Sedimentological geochemistry analyses indicate that the Niutitang Formation formed under high pa-leo-productivity and anoxic-anaerobic even sulfurized conditions.The formation generally has a lower degree of reduction in the late period of sedimentation than at earlier times,and was deposited in a moderately hydrologically restricted setting,with weak terrestrial input and hydrothermal activities.The enrichment of organic matter in the Niutitang Formation slope facies shales was mainly controlled by the redox conditions,however upwelling currents also contributed to the primary input of organic matter.During the early deposition stage of the Niutitang Formation,the nutrients brought by upwelling currents promoted primary paleo-productivity,resulting in the booming of algal organisms and subsequent bacterial sulfate reduction(BSR)and anoxic even sulfurized environments.During the late deposition stage of the Niutitang Formation,a drop in sea level led to a weaker degree of reduction and lower contents of TOC.Our results are of great significance to the enrichment mechanisms of marine organic-rich shales in petroliferous basins.

纵波与转换波数据由于传播路径和传播时间的不同,来自同一反射界面的地震波的运动学特征和动力学特征均不同.因此,纵波与转换波数据进行匹配是一个强非线性反演的过程.论文针对多波地震数据中不同时间域的纵波与转换波匹配问题,基于动态时间规整(Dynamic time warping,DTW)算法,形成了纵波与转换波数据时间域匹配方法和实际数据处理技术流程.从经典的动态时间规整算法入手,改进完善了算法流程以适用于纵波与转换波数据的时间域匹配.在实际数据处理中,首先通过设定初始纵横波速度比,对纵波与转换波数据的预匹配,使纵波与转换波数据满足应用动态时间规整算法的条件.然后,对转换波数据采用动态时间规整算法求取时移量,完成将其从转换波时间域匹配到纵波时间域的过程.经实际多波地震数据的应用,文中提出的纵波与转换波数据时间域匹配方法和技术流程,可以很好地解决纵波与转换波数据匹配过程中的非线性问题,而且在匹配过程中不需要进行层位的控制或约束,就可以达到很好的匹配效果.

深度学习善于从原始数据输入中挖掘其内在的抽象特征,十余年来,其在语音识别、语义分析、图像分析等领域取得了巨大成功,也大大推动了人工智能的发展.本文基于深度学习中广泛应用的卷积神经网络算法,以大庆油田某区块密井网数据为对象,开展自动地层对比试验.实验中,随机选取部分井作为训练样本,对另一部分井分层进行预测,并与原始分层数据比对进行误差分析.按照训练样本的井数据比例65％、40％、20％和10％,将实验分为4组,每组实验包括油层组、砂层组和小层级3个相互独立的实验.12个实验结果表明:训练量越大,地层级别越高(厚度越厚),自动对比效果越好;20％的训练量就可以较可靠地进行砂组及以上级别地层单元(厚度不小于10 m)的自动对比.该实验表明卷积神经网络算法能有效应用于依据测井曲线进行油藏规模地层自动对比,具有良好的发展前景.

在微地震监测过程中,压裂区域的应力状态对于水力压裂的效果有着不可忽视的影响,但是由于压裂区域裂缝形态交错,应力场较为复杂,往往很难有效地获取较为准确的应力状态.本文将探究应力场的复杂程度对于应力反演的影响,通过数值模拟均一应力场条件下和复杂应力场条件下的震源机制解,利用Vavry?uk的迭代联合反演方法进行应力反演,并对反演结果进行误差分析.发现均一应力场作用下震源机制的不确定性对于求解应力模型的影响不大,但是会对滑动方向的误差统计带来一定程度的影响;在复杂应力场的条件下进行应力反演,滑动方向的误差值会随着应力场复杂程度的增加而增大,并且比震源机制的不确定性造成的误差值大得多.此外,当应力场的复杂程度增加到一定水平时,反演得到的单一应力模型将使得相当一部分断层面无法满足摩尔—库伦破裂准则,这种反演结果是不可取的.本文还选择了与数值实验有相似特征的两组实际数据,大庆油田某压裂井和长宁区块的某压裂井监测数据,分别进行应力反演和误差分析,用以验证上述结论.

塔里木盆地经过50多年勘探,证明该盆地油气资源十分丰富,其中,石油资源量120.65×108 t,天然气14.7×1012 m3.目前共发现油气田30多个,其中大型油气田12个,累计探明油气地质储量约23×108 t,天然气储量2×108 m3,油气产量年产3400×104 t油当量,塔里木盆地已成为我国第一大天然气区和油气储产量快速增长的地区.本文论述了塔里木盆地近期油气勘探重大进展、油气分布规律、油气资源潜力及下步勘探方向,对当前和今后油气勘探和科学研究有重要指导作用.

在地震数据的采集过程中,不可避免地会出现地震道缺失或者空间采样不足的情况,这样会产生坏道、缺失道等现象,极大的影响了地震资料质量.想要解决该问题就必须进行地震插值.本文借助于机器学习思想,以无缺失道数据为基础构建机器学习样本集,在此基础上利用随机森林回归预测算法学习各道各时间点振幅与其临近道、时窗内的振幅的统计关系,然后根据临近道数据对缺失道进行补全.将本文所提出方法应用到模型数据与实际采集数据中的缺失道补全处理,均取得良好应用效果,证明本文方法的正确性与有效性.

城市燃气可持续发展研究相对较少,以中国城市燃气为整体研究对象的可持续发展评价仍是空白.本文以系统论和层次分析法工作原理为指导,以城市燃气可持续发展为整体研究对象,通过指标的初选和筛选,构建了由5个子系统和47项具体指标构成的城市燃气可持续发展评价指标体系.在搜集和整理大量原始指标数据基础上,运用因子分析法对城市燃气可持续发展系统进行了分析和评价.2002—2014年,各子系统发展呈上升趋势,但又表现不尽一致.经济子系统波动幅度较大,社会子系统持续稳定增长,资源子系统前紧后松,环境子系统稳中趋缓,技术子系统最为显著.以城市燃气子系统运动的多维空间结构模型为基础,结合因子分析法评价结果,对城市燃气系统整体的发展能力、协调能力、持续能力和可持续发展水平做出评价.总体来看,城市燃气系统发展能力不断增强,整体协调性较高,持续能力稳步提升.在其共同作用下,城市燃气行业可持续发展水平不断提高.

中国在对外贸易的过程中出口了大量隐含能,随着贸易规模的不断扩大,这一现状受到了广泛关注.本文基于2002、2007和2012年投入产出表,从完全消费的视角对中国对外贸易中的隐含石油进行定量分析,并利用敏感性分析方法找到影响隐含石油消费的关键系数,借鉴结构化路径分析方法识别出这些关键系数所在的关键产业路径.核算结果表明,2002—2012年中国隐含石油出口量迅速增加,其中化学工业,电气机械及器材制造业,通信设备、计算机及其他电子设备制造业,交通运输及仓储业的累计消耗比例超过40%.敏感性分析结果表明,石油和天然气开采业到石油加工、炼焦及核燃料加工业,石油加工、炼焦及核燃料加工业到交通运输及仓储业,石油加工、炼焦及核燃料加工业到化学工业等的部门间联系是影响隐含石油出口的关键环节.路径分析表明,批发和零售业,化学工业,研究与试验发展业,非金属矿及其他矿采选业等是高隐含石油出口附加值行业.因此,要努力扩大中间投入的能源效率,推动高附加值行业产品的出口,从而实现外向型经济的低油耗发展.

介孔分子筛材料含有丰富的介孔,它不仅具备微孔分子筛良好的热稳定性和水热稳定性、优异的选择性和活性,而且由于介孔的引入改善了其对大分子的吸附和扩散性能,成为多孔催化材料研究领域的热点.合理地调节孔道结构与表面酸性,成为提高分子筛反应效率、延长其使用寿命的有效途径.本文从介孔分子筛材料的合成方法角度,重点概述了介孔Y型分子筛以及介孔ZSM-5分子筛制备方法的研究现状.

针对具有一定厚度的、整装的特稠油油藏,蒸汽辅助重力泄油(SAGD)相比于其他热采方法,开发效果更好.目前研究认为SAGD主要通过重力机理开采稠油而忽略了注采压差对SAGD开发的影响,导致矿场预测误差较大.本文针对这个问题,对SAGD生产过程中的注采压差进行了详细研究,基于加拿大Mackay River和Dover区块地质参数,建立地质模型,研究了注采压差对采油速度、SAGD开发稳产时间、蒸汽腔上升阶段及蒸汽腔横向扩展阶段的影响.结果表明:注采压差在SAGD开发过程中起重要作用,随着注采压差的增大,采油速度呈现先快速增加后增速变缓的趋势;在蒸汽腔上升初期,腔体呈扇形,一段时间后呈近似六边形;蒸汽腔到达油层顶部并不一定出现最大泄油速度,最大泄油速度一般在蒸汽腔到达油层顶部一段时间之后出现;注采压差影响着蒸汽腔上升扩展角的变化,而扩展角决定着蒸汽腔上升时的波及范围;注采压差在蒸汽腔上升阶段起着重要作用,而在其横向扩展阶段作用开始减弱.因此在现场实践中,SAGD生产前期可以适当的提高注采压差,而在蒸汽腔横向扩展阶段适当的减少注采压差,这样可以降低发生汽窜的概率,从而达到最优经济效益.

页岩气井工程实践表明套管压裂易导致水泥环完整性破坏,进而引发环空带压.统计数据表明:中国涪陵页岩气田投产井166口,出现环空带压井占比达79.52％.进一步分析研究表明:一级套管头(生产套管和技术套管之间)压裂前后带压比例从14.85％提升至50.05％;二级套管头(技术套管和表层套管之间)压裂前后带压井比例从15.84％提升至53.01％,充分说明页岩气井压裂对环空带压影响较大.针对该问题,基于页岩气井压裂工程实际,在考虑压裂液摩擦生热和排量对换热系数影响的基础上,建立了压裂过程中井筒温度场模型和套管—水泥环—地层组合体有限元模型,采用解析法和数值法相结合的方式,计算了页岩气井压裂过程中瞬态温度—压力耦合作用下水泥环径向、切向应力变化规律,开展了井筒内压、压裂液排量、初始温度、弹性模量、泊松比对水泥环应力影响的敏感性分析,并基于Mohr-Coulomb准则对水泥环是否失效进行了分析.研究结果表明:(1)页岩气井压裂过程中,水泥环温度随时间发生剧烈变化,且内外壁之间存在显著温差,该温差随压裂作业的进行先增大、后减小.(2)页岩气井压裂过程中,水泥环径向、切向应力随时间不断变化,径向应力先减小、后增大,切向应力先降低、后升高,然后再降低.依照Mohr-Coulomb准则分析可知,压裂过程中水泥环易发生拉伸破坏,压裂初期为水泥环失效的"风险段".(3)降低井筒内压,可以显著降低水泥环径向、切向应力;降低压裂液排量,水泥环径向、切向应力有所降低,但降低幅度不明显;提升压裂液初始温度,将会提高水泥环径向应力、降低水泥环切向应力;水泥石弹性模量降低至4 GPa时,水泥环径向、切向应力低于水泥石抗拉、抗压强度,在压裂过程中有利于保持水泥环的完整性;提高水泥石泊松比,对径向应力影响极小,可忽略不计,但可以有效降低水泥环切向应力.依据计算结果设计了一种新型水泥浆体系,降低了水泥石弹性模量.应用该水泥桨的工程实践表明,压裂后并未出现环空带压情况,保证了分段压裂后页岩气井的安全生产.研究结果可为页岩气井压裂过程中水泥浆设计以及井筒完整性控制提供参考.

In order to obtain the actual change characteristics of the gas-water relative permeability in coalbed methane(CBM)reser-voirs and to further deepen the understanding of the gas-water production process of CBM reservoirs,a relative permeability dynamic calculation method of CBM reservoirs combined with the real-time production situation of the reservoir was constructed.Firstly,the production history match of the target single coal seam or multiple coal seams is carried out using the multiple coal seam whole process coupling flow model,which is to obtain the basic physical parameters of the reservoir and fluid.Then,based on the obtained basic physical parameters,the full production cycle productivity prediction of the CBM well is carried out.At the same time,the reservoir parameters are averaged according to the real-time expansion behavior of the reservoir pressure drop,and the gas-water permeability curve of the CBM reservoir is calculated based on the averaged reservoir parameters and the actual fluid migration.The results show that the relative permeability dynamic calculation method of CBM reservoirs proposed in this paper can dynamically calculate the actual gas-water relative permeability of the CBM reservoir on the basis of real-time quantitative analysis of the internal production situation of the CBM reservoir.There is a reversal point on the gas relative permeability curve calculated by the method proposed in this paper.The reversal point characterizes the stable and continuous supply of desorption gas in CBM reservoirs.If the actual expansion of the CBM reservoir pressure drop is not considered and the reservoir parameters are averaged in the whole area,the calculated gas-water relative permeability of the CBM reservoir will be low.For multiple coal seam reservoirs,the interlayer mass exchange of fluids and the decrease in the reservoir pressure caused by the crossflow cannot be ignored.The ratio of the crossflow of gas to gas production can reach 0.57,and the ratio of the crossflow of water to water production can reach 0.69 after 3 years of production.The calculated gas-water relative permeability of the CBM reservoir under the condition of ignoring the crossflow is low,which is only 42.9%and 24.4%respectively of the calculated gas-water relative permeability under the condition of considering the crossflow.In the actual production process of CBM wells,the water saturation remains at a high value,more than 40%.Restricted by the high water saturation,the gas relative permeability of CBM reservoirs is low,less than 0.2.

According to the low porosity,ultra-low permeability and neutral partial oil wetting of shale reservoir,the corre-sponding microscopic model of capillary bundle is designed.The wettability of microscopic model changed by the compound system of molecular film agent(DM)and surfactant octadecyl trimethyl ammonium chloride(STAC)was studied.It is found that DM(1000mg/L)/STAC(concentration≤critical micelle concentration),the wetting modified contact angle is positively correlated with the STAC concentration,the maximum contact angle can reach 100.51°,and it is a monolayer adsorption with an average adsorption thickness of 2.064nm;Dm(1000mg/L)/STAC(concentration＞critical micelle concentration),the wetting modified contact angle is negatively correlated with the STAC concentration,and the adsorption layer is multilayer adsorption.Taking shale oil reservoir of Permian Lucaogou Formation in Jimusar sag as a feature,a capillary bundle model equivalent to pore throat diameter was etched,with radius of 5μm and depth of flow channel of 5μm.Then,through DM/STAC wetting modification,based on hydrophilic wetting and wetting modified capillary tube bundle model,the differential pressure-flow method was used to test the fluid percolation law.As a result,when the fluid flows at low speed,it is characterized by non-Darcy percolation and has a threshold pressure gradient.Moreover,the change of wettability causes the capillary force to turn,affecting the law of fluid percolation.

Rock spontaneous imbibiton is the process of wetting phase fluid within the pore space spontaneously exhausting and driving the non-wetting phase,which is one of the important mechanisms for tight reservoirs to improve recovery.Due to the complexity of porous media characteristics and fracture morphology and other factors,the researches on imbibiton and mass transfer laws between fractures and pores have not yet been fully elucidated.In this paper,based on the phase field method and fluid motion equations,a pore-scale dynamic imbibiton and suction numerical model was established to analyze the mass transfer mechanism between fractures and pores within complex pore structures and the relationship with the recovery rate.The results show that:(1)the imbibiton process mainly covers three key stages inside the pore space:rapid penetration of the fracture,interaction between the fracture and the pore space,and gradual advancement in the pore space(i.e.,repulsion process).A faster injection rate will hinder the imbibiton process,and result in more residual oil retention.(2)There is a specific critical fracture width,and when the fracture width is about 40 times the average pore size,the recovery rate will fluctuate up and down in a certain range.As the critical fracture width decreases,the positive correlation between the fracture dimensionless number and the recovery rate is shown.(3)Fracture systems of different complexity have different effects on fluid transport.As the critical fracture width decreases,the impact of different fracture complexity on fluid mobilization is different.Specifically,with the increase of fracture complexity,the wave range of imbibiton effect become larger.The decrease of crack width will exacerbate the phenomenon of oil droplet aggregation,which will significantly slow down the recovery rate and cause clogging problems in the small pore area.(4)The number increase of the system open boundaries can effectively enhance the contact area of the wetting phase,which can maximize the dynamic utilization of the pore space,and form a synergistic seepage drive mechanism.The optimal imbibiton recovery was achieved under the four-sided open(AFO)condition,while the worst recovery was achieved under the one-sided open(OEO)condition.At the same dimensionless time,TEO and OEO show higher normalized recovery rates due to the strong non-homogeneous effect of the open number of end faces and spatial distribution model,while the recovery change curves of the remaining three boundary conditions show relatively concentrated trends.

Unconventional oil and gas resources serve as vital replacement energy in China's hydrocarbon portfolio,and their efficient development is of great significance for safeguarding national energy security.The implementation of staged multi-clus-ter hydraulic fracturing in horizontal wells,along with the optimization of intra-stage cluster design parameters,is critical to maximizing the production potential of unconventional reservoirs.Clarifying fracture propagation mechanisms and quantifying the relationship between fracture geometry and well productivity is key to optimize intra-stage multi-cluster fracturing strategies.In this study,a phase-field method is employed to simulate the competitive propagation morphology of multiple fractures within a fracturing stage.A fracture morphology identification technique is integrated to construct a two-dimensional equivalent fracture model,which can characterize the stimulated flow pathways.Equivalent physical parameters after stimulation are extracted and transferred-together with geometric descriptors-as input for a discrete fracture flow model.This enables automatic coupling and data transfer between the geometric and flow models,thereby facilitating quantitative evaluation of production performance under different fracturing scenarios and ultimately achieving fully coupled fracture propagation-fluid flow simulation.The accuracy and feasibility of the dual-model coupling method are verified through comparison with laboratory-scale physical simulation experiments and field fracturing data.On this basis,the effects of intra-stage cluster number and cluster spacing on fracture morphology and production response are further investigated.The results show that,as the cluster spacing increases from 15 m to 25 m,the fracture deflection point shifts farther from the wellbore,and the tip deflection angle decreases from 30° to 24°.Meanwhile,the pressure gradient around the fracture tip is reduced,weakening the fluid driving force and significantly diminishing inter-fracture fluid interference.This change leads to a decline in peak daily oil production and stabilized production rate,with daily and cumulative oil output decreasing by 35.88%and 35.89%,respectively.In contrast,when the number of clusters per stage increases from 3 to 5,the deflection angle at the tip of the outer fractures increases from 30° to 34°,while the coverage of the induced stress field expands from 36.74%to 42.46%.This results in a higher pressure gradient surrounding the fractures,enhancing the fluid driving force and significantly improving oil mobilization.Consequently,peak daily and cumulative oil production increased by 40.49%and 45.467%,respectively.Therefore,optimizing the intra-stage cluster spacing and cluster number can effectively balance the degree of fracture interference and enhance single-well productivity,thereby improving the overall effectiveness of staged multi-cluster hydraulic fracturing in horizontal wells.

Low salinity water flooding is a new technology for enhancing oil recovery by adjusting the ion composition or con-centration of injected water.However,the applicable reservoir conditions and enhanced oil recovery mechanism of low salinity water flooding have not yet reached a consensus.In this paper,a series of laboratory experiments of wettability control-based low salinity flooding are carried out with plunger rock samples from marine carbonate reservoirs in the Middle East as the research object.Based on the theory of Derjaguin-Landau-Verwey-Overbeek theory(DLVO),an interfacial reaction model of a typical crude oil/brine/rock system is established,and the contact angle and total separation pressure are calculated simultaneously with the augmented Young-Laplace formula.The reliability of the model is verified by the literature experimental data,and the effects of ion concentration and ion type on the separation pressure curve and contact angle are clarified.The results show that in low salinity environments,the pore surface of carbonate rock is more water-wet under the action of fluid flushing,the oil displacement efficiency is higher,and the low salinity water improves the crude oil recovery by 3.2%;under the assumption of constant charge,the mathematical model established based on the DLVO theory for the crude oil/brine/rock system can accurately predict the change of contact angle;compared with the ion concentration,ion type has a greater impact on separation pressure and contact angle.Among divalent ions,Mg2+ions exhibit a more pronounced influence on wettability control compared to Ca2+ions.When the water film thickness is minimal,van der Waals force is the main force affecting the separation pressure.As the thickness of water film increases,the electric double layer force gradually becomes the main force.This study contributes to a deeper understanding of the wettability control mechanism of low salinity water flooding for enhanced oil recovery.

Shale oil is one of the most potential and strategic alternative oil resource in China.It's of great significance to clarify the fluid distribution and evolution laws in porous media for enhancing the recovery of shale oil during the fracturing-soak-ing-producing process.In this work,a multi-component multiphase lattice Boltzmann model was adopted to study the shale oil flow mechanism during fracturing-soaking-producing process.Firstly,the accuracy of the model was verified using Laplace's law,contact angle,and stratified flow.Then,based on the scanning electron microscope(SEM)image of Jiyang shale,the struc-ture of the shale porous medium was constructed including the distribution of fracture and matrix pores.Subsequently,the lattice Boltzmann model was used to simulate the fracturing-soaking-producing process of shale porous media,and the fluid distribution characteristics at different stages were analyzed.Then the effects of different soaking time,reservoir wettability and drainage rate were explored further.The results show that the fracturing fluid will seep into the matrix pore and replace the oil phase under the action of capillary force during the soaking stage,and with the increase of soaking time,the backflow rate of fracturing fluid return tends to decrease;the water-wet core has a better development effect than the neutral and oil-wet cores,and the utilization rate of fracturing fluid and the degree of crude oil utilization in the matrix are higher;the higher drainage rate will make the pore pressure drop rapidly,which is not conducive to the development and production of the shale oil.The fluid flow mechanisms during the shale oil fracturing-soaking-producing process are investigated from a pore-scale perspective,which provides support for the formulation of a reasonable production schedule for shale oil wells.

为明确桂中坳陷北部下石炭统鹿寨组一段成藏条件,评价区块资源潜力,利用录井、地震、实验测试等手段,系统分析页岩气成藏地质特征,并采用静态法对研究区页岩气资源量进行计算.研究表明:鹿寨组一段页岩有机质丰度中等(TOC含量在0.49％～5.15％)、类型好(有机质类型为II1～II2型)、热演化程度适中(热成熟度在2.2％～2.9％);储层脆性指数高(51％～94％),物性条件较好(孔隙度在3.12％～5.02％,渗透率在0.0005～0.161 mD),孔径多小于400 nm;储层孔隙类型以有机质孔和溶蚀孔为主,孔隙比表面积以微孔贡献为主,孔体积则主要由微孔和介孔贡献,微孔发育主控因素包括TOC和黏土矿物,而介孔发育主控因数为黏土矿物;现场总含气量平均1.73 m3/t,甲烷含量高达95％,为高热值干气;甲烷等温吸附绝对吸附量在1.07～3.67 m3/t,页岩吸附能力强;研究区页岩气藏埋藏深度多在1000～3000 m,顶板黄金组和底板尧云岭组岩性以(泥质)灰岩为主,岩性致密,累计厚度分别可达720 m和490 m,区内逆冲断层封堵性好,构造变形程度较低,岩浆活动较弱,温泉水循环深度多在800～1000 m,水文地质开启程度低.研究区沙坪复向斜页岩气地质资源量为255.2×108 m3,技术可采资源量为38.3×108 m3,技术可采资源丰度0.45×108 m3/km2.结论认为,桂中坳陷北部残留向斜核部鹿寨组一段页岩生烃基础较优越、储集空间发育、含气性高、保存条件较好、埋深适中及资源丰度较高,是页岩气勘探开发有利目标.

南华北盆地晚古生代时与鄂尔多斯盆地同属于华北克拉通盆地的一部分,发育广泛的石炭-二叠系煤系地层.其中,太原组不仅是重要的烃源岩层,而且具备良好的致密砂岩气等非常规天然气成藏条件.然而,关于砂岩储层的研究目前尚处于早期阶段,砂岩储层的特征、致密成因和天然气充注特征等一系列关键性问题仍然缺乏详细的研究.本文综合利用铸体薄片、扫描电镜、物性分析、X射线衍射、流体包裹体等实验测试方法研究了南华北盆地太康隆起太原组致密砂岩储层的岩石学特征、成岩特征及成岩作用下孔隙度演化历史,确定了储层致密时间和成因,同时结合地层埋藏史-热演化史,恢复了致密砂岩储层中天然气的充注过程,最终确定了砂岩储层的致密-气体充注之间的耦合关系.研究结果显示:太原组致密砂岩储层主要经历了压实、胶结和溶解等多种成岩作用,当前处于中成岩阶段B期,孔隙类型以次生溶蚀孔隙、黏土矿物晶间微孔和微裂缝为主.通过定量分析不同类型成岩作用对孔隙度的影响,确定压实作用是导致储层致密最主要的因素,造成储层原生孔隙度从38.6％降低了31.01％,黏土矿物、碳酸盐矿物及硅质胶结作用仅使孔隙度损失7.27％,长石、岩屑等颗粒溶蚀作用增孔能力有限(仅为3.28％);孔隙度演化恢复结果表明太原组砂岩储层在中成岩A期的晚期(晚三叠世)开始进入致密阶段.通过对流体包裹体的类型和成分分析,确定太原组砂岩经历过单期次的气体充注过程.含烃盐水包裹体均一温度与地层埋藏史-热史对比结果表明气体充注对应地质时间为229～213 Ma,对应地质历史时期为晚三叠世,与储层致密化时间基本一致,表明太原组砂岩储层属于"边致密边成藏"型储层.

湖相重力流是目前沉积学研究的热点与难点,也是致密油、页岩油富集的有利场所,鄂尔多斯盆地庆城油田三叠系延长组作为致密油、页岩油的典型代表已显示出巨大的勘探开发前景.然而,由于湖相重力流砂体分布认识不清,导致油田并未达到预期的开发效率.本文采用支持向量机(SVR)的机器学习方法,先优选频段再优选属性,建立分频属性与测井解释砂体厚度的非线性映射关系,实现了致密砂岩的定量预测.研究结果表明,低频地震属性适合预测厚层砂体,高频地震属性适合预测薄层砂体;采用机器学习的方法,将不同频率的地震属性智能融合,能够兼顾预测不同厚度砂体,既提高了地震属性的解释精度,又降低了地震解释的多解性,实现了砂体厚度的定量预测.检验结果显示,智能融合属性与砂体厚度的分布趋势与值域区间基本一致,智能融合属性预测砂体分布的可靠性明显提高,与测井解释砂体厚度的相关性由0.60提高至0.79,大多数井点处预测的砂体厚度误差小于5 m.继而,根据融合属性与测井解释,刻画了研究区的沉积微相展布特征:研究区目的层发育湖底扇沉积,细分为分支水道、朵叶主体、朵叶侧缘、滑塌体与朵叶间/水道间5种沉积微相;砂体主体呈扇形连片式沉积,厚度顺物源方向逐渐减薄;分支水道呈窄条带状树形分叉,下切发育于朵叶体之上;朵叶体沉积为研究区的沉积主体;滑塌体为湖底扇前端失稳滑塌形成的小规模孤立砂体,长轴方向多平行于湖底扇前端.研究成果对油田下一步高效开发具有重要意义.

To clarify the distribution characteristics of laminas and cracks in continental shale in the Yanchang Formation of the Ordos Basin,a high-definition camera,super depth of field microscope,IPP software,fractal geometry,Monte Carlo simulation and other means were used to observe and characterize the laminas and cracks of continental shale samples in the Chang 72 oil group.Bright and dark laminas were classified,and the mineral components of bright and dark laminas were compared by X-ray diffraction.The thickness distribution of bright and dark laminas at macro,20 times and 50 times magnification were respectively analyzed,and the distribution rules of average laminar thickness of different thickness classes(below 1 mm,1～10 mm and above 10 mm)were analyzed.The distribution characteristics of crack width,spacing and dip angle were characterized,and a two-dimensional mesoscopic structure model of continental shale was established based on the distribution rules of different types of laminas.The results show that:(1)The minerals in the bright lamina are mainly brittle minerals(80%),such as quartz and feldspar,while the dark lamina is mainly composed of 40%brittle minerals and 40%clay minerals.(2)The fitting result between total laminas thickness and quantity of continental shale laminas follows an exponential function,the fitting between bright laminas thickness and quantity of bright laminas follows a power function,and the fitting between dark laminas thickness and quantity of dark laminas follows a logarithmic function.(3)With increasing observation scale,the frequency of thin laminas(below 1 mm)increases,and the frequency of medium laminas(1～10 mm)and thick laminas(above 10 mm)decrease.There is a linear relationship between the logarithm of different kinds of laminar thickness classes and corresponding average laminar thickness.The distribution of laminar thickness has a fractal feature.(4)The crack width is distributed in the mesoscopic range,with a mean and standard deviation of 0.271 mm and 0.114 mm,respectively,which is relatively concentrated.The mean and standard deviation of crack spacing are 8.115 mm and 8.448 mm,which is relatively uniform.The fitting result between the absolute value of the crack dip angle and the quantity of cracks follows a logarithmic function.

The Early Cretaceous Yingcheng Formation shale gas in the Lishu Fault Depression of the Songliao Basin presents immense prospects for exploration and development.Concurrently,the division of high-frequency sequences within shale intervals has gradually become a research focus.However,traditional sequence stratigraphy faces challenges in the precise delineation of sequences within the shale series,while the understanding of organic matter enrichment patterns within the shale series remains unclear,hindering the exploration and development of shale oil and gas.The utilization of cyclostratigraphy meth-ods allows for the subdivision of high-frequency sequences within the shale series,and further,it provides a beneficial means to explore the enrichment patterns of organic matter in shale based on Milankovitch cycles,aiding in the prediction of"sweet spots"within the layers.Through astronomical cycle analysis of natural gamma-ray data from the research area in the Yingcheng Formation,the following conclusions have been drawn:(1)Well SN65 effectively preserves the signals of Milankovitch cycles within the Yingcheng Formation.Long and short eccentricities serve as reference curves for the fourth and fifth-order sequences,respectively,delineating 14 fourth-order sequences and 51 fifth-order sequences,thus establishing a high-precision isochronous stratigraphic framework for the study area.(2)The organic matter enrichment of the shale within the Yingcheng Formation on the northern slope of the Lishu Fault Depression is controlled by astronomical cycles,exhibiting an antiphase relationship.During periods of high long eccentricity,the climate was warm and humid,corresponding to low Total Organic Carbon(TOC)values;conversely,during periods of low long eccentricity,the climate was cold and dry,corresponding to high TOC values.(3)Two shale sedimentation models have been established:warm-humid and cold-dry.Through the introduction of the concept of the metalimnetic oxygen minimum(MOM),it has been demonstrated that cold-dry environments are conducive to the enrichment of organic matter in shale.(4)The data were divided into 4 organic-rich shale intervals and 3 organic matter-bearing shale intervals based on the half-amplitude points of the long eccentricity cycle curve.High-quality shale intervals develop at the tops and bottoms of various sequences rather than at the maximum flooding surface.Shallow water environments are conducive to the development of organic-rich shale.These research findings not only provide theoretical support for predicting"sweet spots"of shale gas within the Yingcheng Formation in the Lishu Fault Depression of the Songliao Basin but also serve as a reference for the organic matter enrichment patterns in other lacustrine basins,holding significant implications for the evaluation of shale oil and gas exploration selection.

The Yangchungou area is a key replacement area for shale gas exploration in eastern Sichuan in China.Its main control fault,the Yangchungou fault,is an important structure affecting shale gas accumulation in the area,but there are few previous studies,resulting in a low degree of overall research.In order to clarify the structural deformation characteristics of the Yangchungou fault and its geological significance,based on the latest interpretation of three-dimensional seismic data,the geometric characteristics of the Yangchungou fault are described.And we analyze its formation mechanism through fault properties and activity period.Based on this,the relationship between the Yangchungou and Zunyi faults and its influence on shale gas accumulation are discussed.The results show that:(1)The Yangchungou fault is mainly characterized by a planar thrust structure from east to west.The surface outcrop data show characteristics of sinistral compression and torsion.In addition,the Yangchungou fault is characterized by multiple superimposed and nearly parallel thrust slip fault zones along the Silurian and Cambrian,which control the fault development anticline of the middle and shallow deformation layers.(2)The Yangchungou fault is not a part of the Zunyi fault.The structural deformation characteristics of the Yangchungou and Zunyi faults are very different.They show completely different structural styles in seismic profiles.Therefore,the Yangchungou fault and the Zunyi fault are not two parts of the same fault.(3)The Yangchungou fault formed a small fault in a nearly north-south direction during the early Xuefeng orogeny,which caused the Zunyi fault to undergo left lateral reverse washing and sliding.The current form of the Yangchungou fault was formed in the late stage by the reverse compression torsion of the arc-shaped folded wing from east to west.Therefore,the Yangchungou fault has undergone uneven contraction from the Late Jurassic to the Late Cretaceous and reverse sliding from east to west in the Late Cretaceous.(4)The Yangchungou fault has formed the Yangchungou anticline and a complex fracture network.The Yangchungou anticline reduces the depth of shale burial,slows down the evolution of shale maturity,and the complex fracture network increases the storage space,but does not seriously damage the preservation conditions.Both are conducive to the migration and accumulation of shale gas into reservoirs.The development of high and steep strata and compressional and torsional faults can have a destructive effect on shale gas reservoirs.The results of this study can help for better understanding the basin-mountain coupling process and shale gas exploration.

The Baima structure belt in the southern part of Fuling shale gas field has experienced many periods of structural movements since the Lower Paleozoic marine shale gasification,and the structural deformation is complicated and different,which has a controlling effect on the gas content of shale gas reservoirs,making the formation mode diverse and restricting the process of exploration and development.This paper analyzes the structural characteristics and evolution process of the Baima structure belt through 3D seismic interpretation,combined with a series of cores and drilling and logging data,and establishes three modes of shale gas enrichment and reservoir formation on the basis of these data.The study shows that:(1)the Baima structure belt mainly develops north-east oriented structures,and exhibits different deformation characteristics of vertical stratification and east-west stratification.Vertically,it is divided into four sets of upper,middle,lower,and Precambrian structural deformation layers by three sets of sliding layers,namely,the Cambrian Qinjiamiao Formation Salt Bed,the Silurian Longmaxi Formation Mud Shale Bed,and the Triassic Jialingjiang Formation Salt Bed.The plane from west to east can be divided into a fold deformation zone and a wide and slow oblique zone.(2)The late Yanshan period is an active period of structural deforma-tion,and the Jiangnan-Xuefeng orogeny produces extrusion from the south-east to the north-west,forming the main north-east oriented tectonic structure of the Baima structure belt.Himalayan period for the structural transformation and finalization of the period,the Indo-European plate collision and the Tibetan Plateau to the east to escape the remote effect caused by the Sichuan Basin counterclockwise rotation,in the eastern part of the Sichuan region for the performance of the right-handed shear,the development of slip shear zones.The Baima structure belt is extruded in the east-west direction,and the first existing northeast structure is modified,and then it gradually turns into the north-south direction.(3)The Baima structure belt can be classified into three shale gas enrichment and storage modes:low-pressure crushed backslope type,normal-pressure wide and slow sloping type,and normal-pressure gentle sloping type.Among them,the shale gas enrichment and preservation conditions in the south slope of Baima are better,with high gas content in a single well.The core and the east wing of the Baima syncline are followed,and the gas content of a single well is higher.The north wing is poor,and the gas content of a single well is slightly lower.The Shimen-Jinping anticline belt is unfavorable for shale gas enrichment and preservation.

The Jurassic Lianggaoshan Formation shale is a key exploration interval in the Sichuan Basin,but its pore structure and shale oil mobility are still unclear.In order to reveal the reservoir space characteristics and the mobility of shale oil in the Lianggaoshan Formation,this paper divided lithofacies types according to sedimentary structure and mineral composition.Basic geochemical characteristics were obtained by total organic carbon determination,rock pyrolysis and vitrinite reflectance experiments.The porosity and pore structure were characterized and evaluated by means of field emission scanning electron microscopy,nuclear magnetic resonance,low temperature nitrogen adsorption and high pressure mercury injection.The difference in reservoir space characteristics between different rock phases was also compared.With a centrifugation time of 3 h and centrifugation speed of 11 000 r/min,quantitative evaluation of the mobility of shale oil with different lithofacies was carried out by NMR centrifugation and the influential factors are clearly defined.The evaluation model of movable oil quantity logging was established and.the favorable rock facies was selected.The results show that:(1)The TOC of Lianggaoshan Formation shale is mainly between 0.15%～2.95%,the Ro is between 1.06%～1.68%,and the shale is in the mature-high mature stage.After the recovery of light hydrocarbons,the change range of S1 was 0.03 mg/g～3.32 mg/g.The mineral types are mainly clay minerals and quartz.The developed lithofacies are lamellar clay shale facies,lamellar felsic shale facies,lamellar mixed shale facies and massive silty mudstone facies.(2)Shale reservoir space types are mainly clay mineral intergranular pores,organic matter pores,in addition to quartz dissolution pores,interparticle pores,pyrite intergranular pores and microfractures.The porosity is between 1.15%and 4.71%.The shale has a wide pore size distribution.The pore volume is mainly contributed by mesopores and macrop-ores smaller than 200 nm.Laminated clay shale has the best physical properties(3)the movable oil content of the Lianggaoshan Formation shale ranges from 0.25 mg/g to 3.26 mg/g,and the movable oil rate ranges from 5.13%to 44.8%.Lamellar clay shale has the best mobility,and massive silty mudstone has the worst mobility.TOC,clay mineral content and porosity are the key factors controlling movable oil content in the Lianggaoshan Formation.Based on these three factors,a mobile oil quantity pre-diction model is established and verified.Laminated clayey shale is preferred as the key exploration object of the Lianggaoshan Formation,which is indicative of the exploration and development of shale oil in the Sichuan Basin.

陆相页岩油是一个全新领域,近期的勘探实践已在鄂尔多斯盆地、松辽盆地、渤海湾盆地、准噶尔盆地、柴达木盆地等不同页岩层系取得了重要进展,截止2022年底,页岩油探明、控制、预测三级地质储量达44亿t,2022年产量达318万t.页岩油勘探理论和技术也取得了一系列进展,创新了有机母质类型分析与有机质生排烃实验、储层表征技术、页岩油赋存状态与含油性分析、保压取心与现场测试等页岩实验测试分析技术,基本上能满足页岩油相关实验测试要求;在细粒沉积与有机质富集机理、陆相页岩纹层结构与组合类型、储层孔缝结构与储集性、页岩油富集机理取得了一系列新的认识,指导了重点地区选区选带评价研究.研发了烃源岩品质测井评价、储层品质测井评价、工程品质测井评价、岩石物理敏感参数分析和定量预测、多任务学习储层参数预测、各向异性地应力预测、水平井地震地质导向评价、富集层(甜点)综合评价等技术,并推广应用,在页岩油储量提交、甜点区优选、水平井部署、随钻导向预警和钻完井工程改造方面提供了重要且面向全周期的技术支撑.但陆相页岩油规模勘探与效益开发目前还面临诸多挑战,必须建立全新的研究内容与研究重点,特别需要把研究精度升级并要加强微观研究,加强固/液/气多相多场耦合流动机理研究,加强多学科交叉研究等,以建立页岩油成藏新学科.

The progressive application of artificial intelligence technology within oil and gas exploration has resulted in an inevitable shift towards the transformation of geomechanical parameter prediction from a traditional to an intelligent approach.This paper presents a comprehensive review and critical analysis of machine learning algorithms in the direct and indirect pre-diction of rock mechanics parameters,pre-drilling prediction,monitoring while drilling and post-drilling evaluation of formation pore pressure,1D in-situ stresses and 3D in-situ stresses field prediction.Furthermore,the paper compared machine learning models,input parameters,sample data volume,output parameters,and model prediction performance under different tasks.It has been demonstrated that machine learning algorithms exhibit superior performance in terms of accuracy,timeliness,and applicability in geomechanical parameter prediction compared to laboratory tests,field tests,and empirical model calculations.The current research emphasis is on hybrid models,deep learning models,and physical-constrained neural network models,which have been validated as highly accurate,robust,capable of generalization,and easily interpretable.However,the existing research primarily concerns the prediction of 1D geomechanical parameters post-drilling.Consequently,it is not possible to effectively predict 3D geomechanical parameters prior to drilling or during the drilling process.In order to facilitate the digital and intelligent transformation of geomechanical parameters,an intelligent prediction framework for geomechanical parameters is proposed in this paper.This framework considers the influence of multi-source data,including seismic,logging,and mud log data on the prediction of geomechanical parameters.The machine learning model,which is driven by data and physics,enables the prediction of 3D geomechanical parameters.This model is updated in real-time through the most recent drilling data,thus allowing for the pre-drilling prediction,monitoring while drilling and post-drilling evaluation of regional 3D geomechanical parameters.In addition,the key technical problems facing the intelligent prediction of geomechanical parameters are identified:(1)The transformation of unstructured data types should be minimized,the complexity of the data set should be reduced,and the consistency and comparability of the data should be ensured.(2)Multi-source data fusion should be conducted,and multi-source data sets,including seismic,logging,mud log,laboratory tests,and field test data,should be constructed.Subsequently,data processing and feature selection should be performed.(3)Machine learning models should be enhanced to improve performance,integrated models should be adopted to improve prediction accuracy,and mechanism models and domain knowledge should be integrated to enhance model robustness and explainability.

油气渗流力学是油气田开发的理论基础,以连续介质假设和达西方程为基础的单一尺度传统渗流力学及研究方法在油气资源开采中发挥了重要作用.随着缝洞型碳酸盐岩和非常规等油气藏不断勘探开发,储层空隙中的孔隙、裂缝和溶洞,尺度差异达到10个数量级之大,多尺度特征对油气流动的影响越来越大.通常从孔隙尺度、介观尺度和宏观尺度来研究不同尺度上的渗流问题,每个尺度有独特的研究方法,揭示了每个尺度上的特有渗流机理和规律,如何将不同尺度上的渗流机理和规律关联起来,在宏观尺度上形成一套系统的渗流理论,对油气田开发来讲非常重要.因此,尺度升级理论和多尺度方法就变得非常重要,就好比把不同尺度上的一颗颗珍珠串起来,形成完美的一条项链.因此,本文针对油气渗流力学中面临的多尺度现象和科学问题,从孔隙尺度流动、非常规油气宏观渗流、大尺度缝洞碳酸盐岩油气流动和多尺度研究方法等方面系统阐述了尺度升级理论和多尺度方法的研究现状及发展趋势.

Multiphase flow in porous media is an important research topic in the field of oil and gas reservoir development.Due to the complex geological conditions in China,properties of rocks,such as permeability and porosity,are complex and hetero-geneous.The numerical solution for the complex multiphase flow problems needs to overcome challenges such as the system's multiple variables,strong nonlinearity,large computational cost,and the preservation of physical properties.For the traditional incompressible and immiscible two-phase flow model,the IMplicit Pressure Explicit Saturation(IMPES)semi-implicit scheme is a widely-used important algorithm for solving such problems,where the pressure equation is solved implicitly,and the saturation is updated explicitly.However,the traditional IMPES scheme requires the calculation of saturation gradients when updating the saturation.Therefore,it is not suitable for solving the two-phase flow problems in complex heterogeneous media.Hoteit and Firoozabadi proposed an improved IMPES method,allowing the method to reproduce discontinuous saturation in heterogeneous media.However,these two IMPES methods only update the saturation through the mass conservation equation of one phase of fluid,they cannot guarantee that the other phase of fluid also satisfies the local mass conservation property.The derivations of the pressure equations for these two IMPES methods are obtained by adding the volume conservation equations of each phase at the continuous level of partial differential equations,and then using incompletely matched spatial discretization methods for the pressure equation and the saturation equation.Therefore,it is impossible to simultaneously ensure the local mass conservation of each phase for the two-phase fluid.In this paper,based on several types of novel IMPES semi-implicit schemes for solving two-phase flow in porous media that we have published in recent years,we propose a new framework for deriving the pressure equation in IMPES.That is,we first discretize the volume conservation equation of each phase using a spatial discretization method with local conservation,and then add up the discretized volume conservation equations of each phase.In this way,a complete match in spatial discretization between the pressure equation and the saturation equation is achieved.Essentially,it overcomes the difficulty in previous literatures that the IMPES semi-implicit method cannot simultaneously ensure that both phases of the fluid satisfy local mass conservation.The novel IMPES method ensures that each phase of the fluid satisfies local mass conservation,the saturation is bounded,the computational scheme is an unbiased solution,and it is suitable for solving two-phase flow problem with different capillary pressure distributions in heterogeneous porous media.The novel phase-wise conservation IMPES framework proposed in this paper also has an advantage that the traditional IMPES does not have.That is,in the novel phase-by-phase conservation IMPES framework,it is only necessary to define the spatial discretization method of the volume conservation or mass conservation equation,and there is no need to separately define the spatial discretization method of the pressure equation.The solutions of several types of novel IMPES semi-implicit schemes that we have published in recent years can be regarded as special cases of the novel phase-by-phase conservation IMPES framework proposed in this paper.The IMPES framework in this paper can also be applied for more complex multi-component and multi-phase flow in porous media to construct more novel schemes.At the same time,through numerical examples of heterogeneous porous media,this paper verifies the effectiveness and superiority of the novel IMPES method in dealing with two-phase flow problems under complex geological conditions.Compared with the traditional method,it is more adaptable,more stable,and more efficient.

The microscopic occurrence and mobility of oil in shale matrix pores are the key factors that restrict the efficient exploitation of terrestrial shale oil.This paper carried out quantitative characterizations on the amount,proportion,distribution and mobility of oil with different states in shale matrix pores,and theoretically established a series of models evaluating adsorbed,free and mobile amounts,and oil-adsorbed proportion(i.e.,adsorption ratio equation).A method based on satura-tion-centrifugation-nuclear magnetic resonance tests was established to evaluate the microscopic occurrence and mobility of pore oil.The aforementioned models and methods have been applied to the Shahejie Formation shale oil reservoir in the Dongying Sag,Jiyang Depression,Bohai Bay Basin,and revealed the microscopic occurrence and mobility of n-dodecane in shale matrix pores at 20℃and atmospheric pressure.It is concluded that:(1)the amounts of adsorbed and free oil in organic-rich shales are generally higher than those in organic-bearing shales,and the ratio of adsorbed oil to free oil is mainly between 1 and 2.The storage spaces of adsorbed and free oil in different types of shales are obviously diverse.(2)The average density of adsorbed oil of organic-rich shale(0.8331 g/cm3)is slightly higher than that of organic-bearing shale(0.8067 g/cm3).The average thickness of adsorbed oil of organic-rich shale(1.7475 nm)is about 3 times that of organic-rich shale(0.5734 nm).It shows that the organ-ic-rich shale has a stronger oil-rock interaction.(3)The minimum pore diameter of storing free oil(dmin)is equal to the product of the average thickness of adsorbed oil and the pore shape factor.The dmin of organic-rich shale is of 3.5～10.5 nm,and pores of mainly storing free oil(mass ratio>70%)have a diameter of about 100 nm.The dmin of organic-bearing shale varies from 1.1～3.4 nm,and pores of mainly storing free oil have a diameter of about 30 nm.(4)The mobility index of oil in organic-rich shale(mean 6.24 mg·g-1·MPa-1)is higher than that in organic-bearing shale(mean 5.20 mg·g-1·MPa-1),and pore oil has a better mobility when the ratio of adsorbed oil to free oil is about 1.5.(5)Based on the oil-rock interaction,the coupling relationship of the oiliness and storage space of shale with the mobility of shale oil are established,and the internal relation between them is described mathematically,which will lay a theoretical foundation for discovering high-quality shale oil reservoirs.

Shale pores serve as the primary reservoir space for shale gas,whose structural characteristics directly determine the gas occurrence state,enrichment degree,and flow mechanisms.However,the complex structure and strong heterogeneity of organic pores in shale gas reservoirs significantly constrain precise reservoir evaluation and dynamic development.To clarify the three-dimensional structural characteristics of organic pores in the Lower Paleozoic shale reservoirs in South China,this study focuses on two organic-rich shale successions in the northern Guizhou:The Lower Cambrian Niutitang Formation and the Lower Silurian Longmaxi Formation shales,which exhibit significantly different thermal maturities.An integrated approach was employed,combining organic matter extraction,low-temperature nitrogen adsorption,and focused ion beam-scanning electron microscopy(FIB-SEM)three-dimensional reconstruction techniques to systematically characterize the microstructure of organic pores in these two shale successions.Based on nitrogen adsorption and FIB data,the Frenkel-Halsey-Hill(FHH)and box-counting models were respectively applied to evaluate the complexity of organic matter pore structures across different scales.The results show that the moderately mature Longmaxi Formation shale(equivalent vitrinite reflectance Ro=2.1%～2.8%)contains well-developed organic pores,predominantly exhibiting bubble-like and sponge-like cluster morphologies with pore sizes(r)mainly ranging from 200 nm to 450 nm,along with high specific surface area(133.9～159.5 m2/g)and substantial pore volume.In contrast,the overmature Niutitang Formation shale(Ro=3.0%～3.8%)contains smaller organic pores(r=10～140?nm)with irregular or slit-shaped geometries,showing lower specific surface area(30.9～31.4 m2/g)and reduced pore volume.Three-dimensional pore network modeling further reveals distinct connectivity patterns between these two shale successions.In the Longmaxi Formation shale,organic pores are primarily isolated with poor connectivity,and large pores(r>140 nm)contribute approximately 70%of the total pore volume.The Niutitang Formation shale,however,shows enhanced connectivity among large pores(r>150 nm)through thermal-induced microfractures formed during organic matter condensation,while small pores(r<150 nm)remain largely isolated yet account for 64%of the total pore volume.Fractal dimension analysis highlights additional structural differences.The Niutitang Formation shale exhibits higher fractal dimensions for large organic matter pores(D2=2.37～2.78),indicating greater structural complexity,whereas the organic pores of the Longmaxi Formation shale display relatively regular geometries with lower fractal dimensions.These variations are mainly controlled by differences in thermal maturity.Our study provides systematic understanding of three-dimensional pore structure evolution in shales with different thermal maturities,and offers theoretical foundations for shale gas reservoir evaluation and development strategies in northern Guizhou.

Reservoir physical parameters serve as fundamental quantitative indices for characterizing the storage capacity and fluid percolation potential of subsurface reservoirs.Well logging interpretation,a critical methodology for accurately estimating these parameters,constitutes a sophisticated nonlinear regression challenge.To address the inherent limitations of existing petrophysical parameter interpretation techniques,particularly their inadequate generalization performance under few-shot learning conditions,this investigation systematically devises a dual-framework analytical approach.This study initially proposes a sample optimization methodology based on cluster analysis.The spatial configuration of samples is partitioned through the implementation of the K-means clustering algorithm,followed by selective sample curation according to spatial distribution char-acteristics to maximize learning sample diversity.Building upon this optimized sample architecture,the study further introduces a hierarchical residual neural network-based interpretation framework for petrophysical parameter estimation.The proposed methodology enhances conventional fully connected neural architecture through four innovative mechanisms:(1)Integration of cross-layer residual connections facilitates progressive refinement of residual mappings between multivariate logging inputs and target petrophysical outputs,thereby enabling hierarchical abstraction of complex petrophysical relationships from limited training instances.(2)The integration of ensemble learning paradigms amalgamates diverse machine learning methodologies,effectively mitigating overfitting risks through algorithmic diversity.(3)The implementation of a multi-task learning framework establishes intrinsic correlations between porosity and permeability interpretation tasks via shared latent representations,thereby enhancing individual task generalizability under data scarcity constraints.(4)The introduction of a quadratically weighted root mean square error loss function preferentially reduces interpretation errors in high-permeability reservoir intervals.Results from 90 rigorously designed comparative experimental configurations in the study area demonstrate that the cluster-based sample opti-mization methodology effectively enhances generalization performance across multiple machine learning models under few-shot learning constraints.Application of the proposed hierarchical residual neural network framework for well-logging interpretation of reservoir porosity and permeability within the investigated reservoir area achieves coefficients of determination of 88%and 94%,respectively,demonstrating statistically significant superiority over conventional methodologies in both petrophysical interpretation accuracy and generalization capability.Blind testing validation on cored wells reveals 12 and 20 percentage point improvements in predictive precision compared to other various existing methodologies,the proposed approach in this study demonstrates substantial advancements in addressing few-shot learning challenges through algorithm optimization strategies encompassing distribution-based sample selection and multi-task collaborative frameworks.This methodology significantly enhances feature representation fidelity in petrophysical datasets,exhibiting superior petrophysical interpretation accuracy and enhanced generalization capabilities.

Total organic carbon(TOC)content is a crucial geochemical parameter for assessing reservoir quality and hydro-carbon generation potential of source rocks.The accurate prediction of TOC content is important for optimizing the exploration and development processes of shale oil and gas.With the rapid development of artificial intelligence technologies,individual machine learning algorithms have been increasingly applied to evaluate TOC content in shale.Despite the promising results of the individual machine learning algorithms,they are often subject to several challenges including overfitting,underfitting,and getting trapped in local optima of objective function.To address these limitations,the ensemble learning models are developed.Ensemble learning models leverage the strengths of multiple individual intelligent algorithms to enhance prediction accuracy and stability.Among them,combination strategy is one of the key factors in optimizing the ensemble learning models.Arithmetic average method as the simplest combination strategy fails to fully use prediction performance of the best individual intelligent model,and it can be severely affected by the individual intelligent model with a large prediction error,which can interfere with prediction outcome of overall model.In comparison,weighted summation method as a common combination strategy assigns the weights to different individual intelligent models according to their performance on training data.This method will perform excellently on training set,but it tends to have a poor performance when applied to test set.This paper develops an ensemble model based on an intelligent matching technology(IMTEM).The proposed method utilizes a set of robust intelligent algorithms including extreme gradient boosting,random forest,support vector machine,and extreme learning machine as algorithm modules to initially process input data.Then,the processed feature information combined with original log responses is fed to feedforward neural network layer for nonlinear transformation and feature learning,thereby enabling accurate and continuous estimation of TOC content in shale.To validate effectiveness of the IMTEM,the proposed method is applied to the prediction of TOC content in the Longmaxi Formation shale in the Sichuan Basin.Test results indicate that,compared to two ensemble models,five baseline models,and the ΔlogR method,predictions of the IMTEM exhibit higher consistency with measured TOC content.This demonstrates that the IMTEM is more suitable for predicting TOC content in shale.

To address the challenges of the oil-based drilling fluid system's deteriorating rheological properties and insufficient plugging pressure resistance under high-low temperature cycling conditions in the Yaha gas storage reservoir drilling,a tempera-ture-sensitive high-temperature thickener,RHT,was developed.Optimized plugging materials and supporting agents were selected to construct a high-temperature resistant oil-based drilling fluid system.Characterization methods,including infrared spectroscopy,nuclear magnetic resonance hydrogen spectra,thermogravimetric analysis,and differential scanning calorimetry(DSC),were used to analyze RHT's molecular structure,thermal stability,and temperature-sensitive characteristics in depth.The systematic evaluation of its rheological control in emulsions and oil-based drilling fluids was conducted.Experimental results showed that RHT significantly improved the shear-thinning and thixotropic properties of the emulsion,demonstrating excellent rheological control capabilities under high-low temperature cycling conditions.At 80℃,the dynamic yield stress increased by 87%without any increase in plastic viscosity;at 220℃,the dynamic yield stress increased by 220%,with a dynamic plastic ratio of 0.49 Pa/(mPa·s).The drilling fluid system maintained strong rock-carrying capacity after aging at 220℃and effectively sealed 20～40 mesh sand beds and 1～3 mm cracks,achieving a maximum pressure resistance of 8 MPa.In the field application of the Yaha gas storage reservoir well X,this system significantly enhanced the rock-carrying and plugging performance of the drilling fluid,reducing complexities such as fluid loss and stuck pipe incidents,thereby providing strong technical support for the efficient development of the Yaha gas storage reservoir.

In order to investigate the deformation characteristic and transport behavior of oil-water micro-interface and its evolution law under different wettability conditions in water flooding,a Hele-Shaw cylindrical model has been constructed based on the N-S equation.Phase field method has been employed to track the topological deformation characteristics of oil-water micro-interface in water flooding.The effect of wettability,oil-water viscosity ratio,and capillary number on the deformation characteristic and evolution process of oil-water micro-interfaces has been studied.The simulation results show that the dynamic evolution process of oil-water micro-interfaces observed from the model surface in water flooding can be divided into four stag-es,including breakthrough,fracture,three-phase contact line intersection,and micro-interface merging.The breakthrough and fracture phenomenon of oil-water micro-interfaces can be observed repeatedly in the displacement process,and is not affected by wettability and rock particle distribution.Three-phase contact line intersection and micro-interface merging phenomenon have the similar deformation characteristics and evolution law in the vertical profile of the model,which are mainly influenced by wet-tability and rock particle distribution.Three-phase contact line intersection phenomenon occurs more frequently under water-wet condition,while the micro-interface merging phenomenon occurs more frequently under oil-wet condition.The change amplitude of displacement front decreases and then increases in water flooding as wettability changes from strong water-wet to strong oil-wet,which exhibits the piston-like displacement under weak water-wet condition.The simulation results show that the highest oil displacement efficiency is observed under weak water-wet condition,while the lowest oil displacement efficiency(61.06%)is observed under strong oil-wet condition.Moreover,as the oil-water viscosity ratio increases from 20 to 100,the occurrence rate of three-phase contact line intersection phenomenon decreases,the micro oil displacement efficiency decreases by 8.56%,and the initial displacement pressure also increases under weak water-wet and the same injected pore volume multiple condition.As the capillary number increases from 0.66×10-3 to 2.0×10-3,the occurrence rate of three-phase contact line intersection phenomenon increases,the volumes of residual oil decreases,the micro oil displacement efficiency increases by 9.36%,and the displacement pressure also decreases under weak water-wet and the same injected pore volume multiple condition.This reveals that the micro oil displacement efficiency can be significantly improved by increasing the occurrence rate of three-phase contact line intersection phenomenon under water-wet condition.The research results can enrich the micro flow mechanism in water flooding,and provide a theoretical basis for further explore and utilize the residual oil.