顺西地区良里塔格组裂缝特征及石油地质意义

Fracture Characteristics and Petroleum Geological Significance of Lianglitage Formation in Shunxi Area

塔中顺西区块位于卡塔克隆起西北倾末端,奥陶系良里塔格组储层以裂缝–溶蚀孔洞型为主。研究表明,工区内裂缝可分为构造缝和非构造缝两类,其中构造裂缝可分为垂直裂缝、斜交裂缝(高角度裂缝、低角度裂缝)和水平裂缝;非构造缝有压溶缝合线缝与成岩缝;构造裂缝中斜交裂缝相对发育,垂直裂缝和水平裂缝欠发育,斜交裂缝走向以NW、NWW向为主,次为NE走向;构造缝可大致分为3期活动,即加里东中晚期—海西早期、海西晚期和印支—燕山期。进一步分析表明,工区内构造应力场、断裂、岩性、物性和层厚与裂缝密切相关,局部构造高点、枢纽部位,转折端、断裂的交汇处、脆性岩性、物性和地层厚度等控制了裂缝的发育。工区内裂缝具有十分重要的石油地质意义,它不仅自身可作为良好的储集空间,而且是储层发生岩溶作用的有利通道并能在一定程度上扩大岩溶作用范围;在油气运聚过程中,裂缝是良好的油气运移通道,对油气成藏起着至关重要的作用。

Shunxi Area of middle Tarim Basin is located in the northwest pitching end of Katake uplift. Lianglitage Formation reservoir of Ordovician is mainly fracture-cavity reservoirs. The studies show that cracks can be divided into the structural ceacks and non structural cracks. The structural cracks can be divided into vertical fractures,oblique fractures（high angle fractures,low angle fractures）and horizontal fractures;the non structural cracks contain pressure dissolved stitch seam frac-tures and diagenetic fractures;the oblique fractures is relatively more than vertical fractures and horizontal fractures,and trend of oblique fractures is mainly NW,NWW,followed by NE. Structural fractures have three stages of activities：late Cale-donian-early Hercynian,late Hercynian and Indosinian-Yanshan periods. Further studies show that tectonic stress field, fracture,lithology,physical property and layer thickness is closely related to the crack. The crack growth is conteolled by local structural high,key parts,turning point,the junction of the brittle fracture,lithology,physical property and thickness of strata. Cracks in the area have very important significance in petroleum geology,which can not only be used as good reservoirs,and also favorable channel and in some extent it can expand karst effect;in the oil and gas migration and accumulation process, cracks are good oil and gas migration channel for karst effect,plays a vital role in oil and gas accumulation.