麦盖提斜坡石炭系碳酸盐岩微地震相特征与储集层预测

Microseismic facies analysis and reservoir prediction for Carboniferous carbonates in Meigait Slope, Tarim basin.

塔里木盆地西南坳陷麦盖提斜坡石炭系碳酸盐岩 (Tg2′和Tg2″反射波组 )非均质性严重 ,非储集层段基本为强振幅连续微地震相 ,而储集层发育段为弱振幅的连续或不连续反射微地震相。利用目的层微地震相特征 ,可寻找有利的碳酸盐岩储集层发育带。根据井下碳酸盐岩储集层发育段与过井地震剖面的地震 地质层位标定结果 ,建立了麦盖提斜坡微地震相特征与碳酸盐岩储集层发育段的相关模式。对斜坡西部群苦恰克地区石炭系小海子灰岩段底的Tg2′反射波组和斜坡东部石炭系巴楚组生屑灰岩段底的Tg2″反射波组进行微地震相分析 ,结合已知井下碳酸盐岩沉积相与储集层发育特征、储集层所处构造 (古构造、现今构造 )位置 ,预测碳酸盐岩储集层发育有利地区。研究认为 :群苦恰克地区石炭系小海子灰岩段岩溶发育带主要分布在巴什托普背斜构造带的西南翼 ;玛扎塔克构造带以南地区石炭系巴楚组生屑灰岩段有利储集层发育区主要分布在该区 4个潜山区及其附近。图 3参

Carboniferous carbonate reservoirs in Meigait Slope, Southwest depression of Tarim basin is seriously anisotropic. The microseismic facies analysis of target intervals is helpful to find out favorable carbonate reservoir zones. Based on the seismogeology marking results of downhole carbonate reservoir zones and seismic profiles across wells, the authors set up the relationship between the microseismic facies and the carbonate reservoirs, and finished the microseismic facies analysis on the reflector (Tg2′) of the bottom of the Carboniferous Xiaohaizi Limestone Member in Qunkuqiake, the west of Meigait Slope, and on the reflector (Tg2″) of the bottom of Bioclastic Limestone Member of Carboniferous Bachu Formation in the east of Meigait Slope. Some promising exploration zones of carbonate reservoirs are proposed in the paper according to the analysis of the downhole carbonate sedimentary facies and reservoir characteristics, the tectonic location (paleostructure, neotectonic) of reservoir beds, as well as the microseismic facies analysis. The result shows that the karst development zones of Carboniferous Xiaohaizi Limestone Member ocurred mainly in the southwest part of Bashituopu anticlinal belt in Qunkuqiake areas, and the favorable reservoir zones of Bioclastic Limestone Member of Carboniferous Bachu Formation are distributed predominantly over the A, B, C, D four buried hills in the south of Mazhataki structural belt.