柴达木盆地干柴沟—咸水泉地区中—深层成岩演化及其对储集体性能的影响

Diagenetic evolution and its influence on reservoir properties of the middle-deep strata in Ganchaigou-Xianshuiquan region of Qaidam Basin

通过剖面观察、岩心描述、分析化验等手段,系统研究了柴达木盆地干柴沟—咸水泉地区中—深层储集体岩石学特征、主要成岩作用类型及特征、储集空间类型及特征、成岩阶段及成岩演化序列,以及成岩作用对储集体性能的影响程度和规律。结果表明:研究区中—深层储集体主要由成分及结构成熟度均为低—中等的各类砂岩和部分泥灰岩组成;以压实作用、胶结作用、充填作用为主的破坏性成岩作用造成了储集体孔隙空间的大量损失,而以溶蚀作用为主的建设性成岩作用则使部分储集体恢复了储集性能;破坏性成岩作用主要发生在同生成岩、早成岩和中成岩阶段,建设性成岩作用主要发生在褶皱回返引起的表生成岩阶段;受成岩作用影响,主要发育粒间孔、残余粒间孔和溶蚀孔隙,孔隙结构以微细喉型为主,储集层类型以低孔—特低渗储集层为主。

Through observed outcrop sections,described cores from formations,analyzed test reports,and many other data,the reservoir rock characteristics,the main types and characteristics of diagenesis,diagenetic stage and evolution succession of middle-deep strata in Ganchaigou-Xianshuiquan region of Qaidam Basin in Qinghai Oilfield were studied systematically,and the influence and discipline of diagenesis on the reservoir properties were revealed clearly.The result shows：In this region,the reservoir mainly consisted of all kinds of sandstone and part of the marlite with low to medium component and textural maturity.Destructive diagenesis including compaction,cementation and filling,caused heavy loss of the pore space of the reservoir,while the constructive diagenesis,mainly including dissolution,rebuilt part of the reservoir with better reservoir properties.Destructive diagenesis mainly occurred in the syndiagenetic stage,early diagenetic stage and middle diagenetic stage,and constructive diagenesis mainly generated in the epidiagenetic stage as a result of continued orogenetic Altun mountains by the Neotectonic movement.Affected by diagenesis,intragranular pore,residual intragranular pore and issolution pore were mainly developed,most pore textures were high complex with superfine throat,and the reservoir mainly were made up of the type with low porosity and superfine permeability.