基于原子力显微镜表征的含油储层微观孔隙结构分析及应用

为研究岩心微观孔隙结构在强碱三元复合驱替过程中的变化特征,以大庆油田南5-4-检725井855.0m处岩心为对象,通过原子力显微镜观察岩心形貌特征,定量分析孔喉宽度和深度;分析驱替过程中岩心样品的面孔率、孔喉宽度和深度、分形维数等参数变化反映的微观孔隙结构变化规律.结果表明:原子力显微镜获得的图像可以真实反映储层岩石微观形貌特征,储层微观孔隙结构具有二段式分形特点.微观孔隙结构变化特征在驱替初期,主要表现为岩石粒间颗粒运移;在驱替中后期,主要表现为强碱三元驱替剂与岩石相互作用,生成驱替剂残留或其他产物.该研究结果对分析强碱三元复合驱替后剩余油分布规律、制定后续开发方案具有指导意义.     

扶余油田东5-9区块扶杨油层储层构型及剩余油分布模式

针对扶余油田扶余油层、杨大城子油层砂体分布特征及重建地下认识体系关键技术的难点,在分析水下分流河道和曲
流河沉积储层形成的基础上,采用层次分析思路,综合运用岩心、密井网测井等资料,将扶余油层划分成复合河道、单一河道、河道
内加积体等构型要素,将杨大城子油层划分成河道、点坝、点坝内侧积体等构型要素,并识别了不同构型界面的岩心、测井响应特
征和井间对比标志。最后探讨了剩余油成因及分布模式,扶余油层有孤立单一河道型、切叠河道砂体型、单一河道内部加积体控
制局部富集薄层型等类型。杨大城子油层有孤立型、点坝侧积泥岩遮挡型等类型。      

Effects of seasonal water-level fluctuation on soil pore structure in the Three Gorges Reservoir,China

Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability. The aim of this study was to investigate the response of soil pore structure to seasonal water-level fluctuation in the reservoir, and particularly, the hydrological change of wetting and drying cycles. Soil pore structure was visualized with industrial X-ray computed tomography and digital image analysis techniques. The results showed that soil total porosity(? 100 ?m), total pore number, total throat number, and mean throat surface area increased significantly under wetting and drying cycles. Soil porosity, pore number and throat numberwithin each size class increased in the course of wetting and drying cycles. The coordination number, degree of anisotropy and fractal dimension were indicating an increase. In contrast, the mean shape factor, pore-throat ratio, and Euler-Poincaré number decreased due to wetting and drying cycles. These illustrated that the wetting and drying cycles made soil pore structure become more porous, continuous, heterogeneous and complex. It can thus be deduced that the water-level fluctuation would modify soil porosity, pore size distribution, and pore morphology in the Three Gorges Reservoir, which may have profound implications for soil processes, soil functions, and bank stability.     

Identifying and Evaluating of Oil Reservoir

The identification and evaluation of oil reservoir with logging data are one of most important ways in geologic logging services. For the last decades, with the further development of the oil & gas exploration, great advances have been achieved in techniques on the acquisition, processing and interpretative evaluation of logging data. How to identify fluid characteristics and evaluate the productivity in light oil reservoir (the crude density being between 0.74g/cm3 and 0.82g/cm3)has become one of the difficulties.With the establishment of the regional interpretation criterion of the study blocks, the optimized logging parameters that reflect the reservoir characteristics have been used to establish the chart for the interpretation of oil-water reservoir combining with well logging parameters. Then, to begin with geologic reserves of crude in single well, we establish evaluation criterion for productivity in oil reservoir with determining lower limit value of the reservoir and applying the relationship between chart parameters. The techniques are verified in production and get better effect.On the basis of the reservoir characteristics analysis of both basin A and B, We established the evaluation method of static productivity on light oil reservoir with getting quantitative evaluation parameters after quantitatively evaluating the date of core, pyrolysis chromatogram and gas chromatogram. It provides new technique 7 for new well interpretation and old well review, as well as evidence for project.design of well testing.     

基于CT扫描技术的低渗油藏水敏效应后微观孔隙结构特征

为了研究水敏效应对低渗油藏微观孔隙结构特征的影响,将CT在线扫描技术和岩心驱替实验相结合,开展了低渗油藏不同渗透率岩心水敏性评价实验,对水敏过程中孔、喉半径分布特征、配位数、孔隙变化特征、物性参数变化及对储层渗流能力的影响进行了实验研究,并绘制了水敏前后极限注采井距对比图版。结果表明,随着渗透率降低,水敏效应对孔隙、喉道伤害程度越大、平均孔喉配位数减少越多。两者共同作用是造成储层启动压力梯度增加的主要原因;水敏效应对储层喉道伤害程度远大于对孔隙伤害程度;水敏效应造成黏土膨胀、颗粒运移几乎发生在所有孔隙中,但对岩心整体孔隙结构和分布特征影响不大。通过极限注采井距可知,水敏效应造成新沟嘴组低渗油藏极限注采井距减少了153 m,需要通过加密井来调整注采井距,改善注水波及范围。该研究结果对长期注水的水敏性低渗储层开发调整具有现场指导意义。     

油气储层中孔隙尺寸分级评价的讨论

常规-非常规油气协同发展引发储集体类型的多样性,品质整体变差,孔隙结构更为复杂,亟需建立相对统一的孔隙结构评价方案,为储层评价与甜点区优选提供技术支持。基于岩石孔隙结构解剖,提出“孔隙结构四分法”评价方案,将孔隙系统分为毫米孔(大于1 mm)、微米孔(1~1 000 μm)、亚微米孔(100~1 000 nm)及纳米孔(小于100 nm);明确了不同类型孔隙系统发育位置、流体作用力及流动机理,建立了对应的分析评价技术。解剖了克拉2气田巴什基齐克组常规砂岩、新安边油田长7段致密砂岩、川中大安寨段介壳灰岩、川南龙马溪组页岩4类储层,明确了各储层类型孔隙结构的差异性及不同级别孔隙所占比例,探讨了孔隙结构对储层物性、资源经济性及开发工艺的影响;孔隙结构分级研究需与储层有效性评价紧密结合,特征尺度决定流体相态与作用力,影响流体可动性及油气开发工艺。进一步加强孔隙分级评价关键界限值的研究,完善孔隙结构表征技术的融合,建立孔隙结构与岩性和产能的定量关系是未来研究的重点。      

碳酸盐岩储层孔喉结构和储层参数的分析与反演

针对强非均质性碳酸盐岩储层微观孔喉结构差异所导致的孔隙度相似、渗透率和饱和度存在较大差异这一现象,开展
了孔喉结构的评价。基于孔隙度和渗透率,衍生出储层参数RQI 和RQF ;划分了压汞曲线的类型、分析了压汞曲线的形态,提取
了异于砂岩的压汞参数(SHg/pc)max;同时引入胶结指数m 值。以RQI 和RQF 为核心参数,建立各参数间的函数关系,以满足资
料丰度较弱的情况下孔喉结构的评价需求。另外,基于(SHg/pc)max与RQI 之间的相关性,在每个进汞压力测试点下,建立了SHg
与RQI 之间的函数关系,达到重构压汞曲线的目的。鉴于核磁T2 几何平均值与RQI 之间的相关性,可以利用T2几何平均值反
演储层的渗透率。分析碳酸盐岩储层孔喉结构和储层参数之间的关系,为完成孔喉结构的评价和储层参数的反演奠定了一定的
理论和实践基础。      

鄂尔多斯盆地杭锦旗独贵加汗区带下石盒子组储层特征及孔隙演化

杭锦旗地区独贵加汗区带是鄂尔多斯盆地北部天然气勘探开发的重要对象,区带内下石盒子组砂岩储层非均质性强,含气饱和度差异大,前人对致密储层发育特征及其孔隙演化历史研究不够系统和深入。基于钻井岩心、岩石薄片及相关测试等资料,在统计、对比分析独贵加汗区带下石盒子组砂岩储层岩石学与物性特征的基础上,通过成岩作用分析,厘定控制储层孔隙发育的主要因素,进而重建主要储层段的孔隙演化历史。研究表明,杭锦旗地区独贵加汗区带下石盒子组砂岩多属超低渗透储层,局部存在裂缝发育的高渗透率段;压实作用和胶结作用对研究区储层孔隙演化起破坏性作用,减孔率分别为84.8%和7.1%,而溶蚀作用为建设性成岩作用,增孔率9.5%;盒一段储层现今孔隙度基本继承了早白垩世末期的特征,孔隙演化历经早成岩阶段A期压实与胶结作用快速减孔,B期持续压实减孔,中成岩A期溶蚀增孔作用与压实-胶结减孔作用并存及B期变化微弱等过程。      

Variation law of microscopic pore of loess-like soil after several freeze-thaw cycles in seasonal frozen soil region

In seasonal frozen soil region,the engineering geological properties of loess-like soil will be deteriorated after freeze-thaw cycles.Through the freeze-thaw cycle experiment of remolded loess-like soil,under different freezing temperatures,the authors carried out freeze-thaw cycle tests for 3 times and 20 times,respectively.With mercury intrusion porosimetry and granulometric analysis,from the micro-structure,the authors studied the law that freeze-thaw cycle times and frozen temperature effect on the variation of microscopic pore of loesslike soil.This result can provide theoretical basis for comprehensive treatment of problems in the construction of the project in seasonal frozen loess-like soil region.     

羌塘盆地隆鄂尼—昂达尔错地区布曲组白云岩储层成因及孔隙演化特征

利用剖面地质调查、岩心观察、薄片铸体鉴定、扫描电镜分析及物性测试等方法,结合地球化学资料综合分析,研究羌塘盆地隆鄂尼—昂达尔错地区布曲组白云岩储层成因及孔隙演化特征。结果表明:布曲组白云岩包括保留先驱灰岩原始组构白云岩、晶粒白云岩和白云石充填物;晶粒白云岩中细晶、自形白云岩储层物性最好,细晶、半自形白云岩储层物性次之;储集空间以晶间孔为主,局部发育晶间溶孔。布曲组沉积前的古地貌和沉积时的古气候控制白云岩在垂向和平面上的展布,即沉积环境决定储层的叠置形态;白云岩储层发育于台缘滩和台内浅滩环境,高位体系域晚期的咸化海水提供白云石化流体;白云岩储层经历准同生阶段、浅埋藏阶段、中—深埋藏阶段及构造热液改造阶段,浅埋藏阶段是储层孔隙发育的关键时期。在南羌塘地区,早白垩世晚期羌塘地块和拉萨地块的碰撞以剪切作用为主,形成深大断裂,大气淡水下渗稀释布曲组地层水,并俘获夏里组高~(87)Sr/~(86)Sr的地层流体,约74 Ma的构造热事件提供鞍形白云石的热源,形成鞍形白云石充填物。