鄂尔多斯盆地东部佳县—清涧地区上古生界低渗透储层压裂地质特征研究

发布时间：2018-04-04 05:33

本文选题：鄂尔多斯盆地　切入点：低渗透储层　出处：《长安大学》2017年硕士论文

【摘要】：鄂尔多斯盆地是我国最大的石油和天然气勘探、开发基地之一,目前盆地东部探明天然气储量已达上万亿方。盆地东部上古生界地层发育齐全,具有较好的勘探潜力。但是该区储层成岩作用复杂、储层岩石力学性质和内部的构造裂缝分布规律不明显,这些因素是导致该区压裂改造效果差的主要原因。为提高研究区气藏压裂改造效果,本论文针对佳县—清涧地区主力含气层系石盒子组盒8段和山西组山2段系统地开展储层岩相学、岩石力学性质以及裂缝发育特征等方面的相关研究工作。取得的主要结论和认识如下:1.通过岩相学观察,将研究区上古生界低渗透储层砂岩划分成杂基蚀变充填强压实致密成岩相、石英加大硅质胶结粒间孔成岩相、未溶蚀钙质胶结交代致密成岩相、钙质胶结溶蚀孔成岩相、杂基溶蚀孔成岩相和岩屑溶蚀孔成岩相。。2.研究区储层中不同成岩相砂岩的抗压强度、弹性模量和泊松比均有所差异,脆性矿物含量、硅质胶结物含量以及压实重结晶程度越高的成岩相,则其抗压强度越大,反之则越小;孔隙度越大的成岩相,弹性模量越小;石英等脆性矿物含量越高、压实程度越弱、孔隙度越高的成岩相,则其泊松比越小,反之则越大。3.研究区储层中不同成岩相砂岩的可压裂性有一定的差异,脆性系数较大的石英加大硅质胶结粒间孔成岩相、钙质胶结溶蚀孔成岩相和杂基溶蚀孔成岩相可压裂性好,杂基蚀变充填强压实致密成岩相和未溶蚀钙质胶结交代致密成岩相和岩屑溶蚀孔成岩相砂岩可压裂性相对较差。4.研究区主要发育倾角大于60°的高角度剪性裂缝,且以近E-W向的裂缝最为发育。按照裂缝野外的交切关系可将其分为近E-W与近S-N向和NW-SE与NNE-SSW向两套裂缝系统。近E-W与近S-N向裂缝系统指示了燕山期的构造应力场,NW-SE与NNE-SSW向裂缝系统指示了印支期的构造应力场。压裂人工造缝时,应避开研究区较发育的裂缝系统,避免压裂施工时打开原本存在的天然裂缝,从而使压裂形成新的人工裂缝和裂缝网络,使压裂效果显著提升。
[Abstract]:Ordos Basin is one of the largest oil and gas exploration and development bases in China.The Upper Paleozoic strata in the eastern part of the basin are well developed and have good exploration potential.However, the diagenesis of reservoirs in this area is complicated, the mechanical properties of reservoir rocks and the distribution law of structural fractures in the reservoir are not obvious, these factors are the main reasons for the poor effect of fracturing reconstruction in this area.In order to improve the effect of fracturing in gas reservoirs in the study area, this paper systematically develops reservoir petrography for Shihezi formation No. 8 of the main gas-bearing strata in Jiaxin-Qingjian area and Shan2 member of Shanxi formation.Related research work on rock mechanical properties and fracture development characteristics.The main conclusions and understandings are as follows: 1.Through petrographic observation, the sandstone of low permeability reservoir of Upper Paleozoic in the study area can be divided into complex base alteration filling compacted tight diagenetic facies, quartz increasing siliceous cemented intergranular pore diagenetic facies, undissolved calcareous cemented metasomatic tight diagenetic facies.Calcareous cemented dissolution pore diagenetic facies, complex base dissolution pore diagenetic facies and lithic lithic dissolution pore diagenetic facies.The compressive strength, elastic modulus and Poisson's ratio of sandstone with different diagenetic facies are different in the study area. The higher the content of brittle minerals, the content of siliceous cementation and the degree of compaction recrystallization, the greater the compressive strength of the diagenetic facies.On the contrary, the smaller the diagenetic facies, the smaller the elastic modulus of the diagenetic facies with larger porosity, the higher the content of brittle minerals such as quartz, the weaker the compaction degree and the higher the porosity of diagenetic facies, the smaller Poisson's ratio is, and the larger. 3.The fracturing property of sandstone with different diagenetic facies is different in the study area. Quartz with high brittleness coefficient increases siliceous cemented intergranular pore diagenesis facies, calcareous cemented solution pore diagenetic facies and complex base dissolution pore diagenetic facies have good fracturing property.Compression-compacted dense diagenetic facies and undissolved calcareous cemented metasomatic tight diagenetic facies and lithic dissolution pore diagenetic sandstone have relatively poor fracturing ability .4.High angle shear fractures with dip angle greater than 60 掳are mainly developed in the study area, and those near E-W direction are the most developed.According to the intersecting relation of fracture field, it can be divided into two sets of fracture systems: near E-W and near S-N and NW-SE and NNE-SSW.The near E-W and near S-N fracture systems indicate the tectonic stress field of Yanshanian period. The NW-SE and NNE-SSW fracture systems indicate the tectonic stress field of the Indosinian period.In artificial fracturing, the developed fracture system in the study area should be avoided, and the existing natural fractures should be avoided during fracturing operation, so that new artificial fractures and fracture networks can be formed, and the fracturing effect can be greatly improved.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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