塔里木盆地麦盖提西部地区上石炭统不整合及储层发育模式

Upper Carboniferous unconformity and reservoir development model of the western Maigaiti area,Tarim Basin

塔里木盆地麦盖提西部地区发育有巴什托、亚松迪等石炭系油气藏,油气前景广阔,但石炭系储层发育模式还有待深入研究。通过地震和钻/测井地层对比来分析不整合面特征,以岩心和地震相结合来研究储层发育特征。晚石炭世的巴楚运动造成了麦盖提西部区域抬升剥蚀,形成了T_5~5(卡拉沙依组/小海子组)和T_5~4(小海子组/南闸组)2期不整合。其中T_5~5为构造不整合,形成隆起、斜坡、谷地等岩溶地貌,发育渗流带—浅部潜流带和深部潜流带2套喀斯特岩溶体系,岩溶斜坡发育较好的储层;而T_5~4为地层不整合,主要受到古地貌和海平面变化控制,在小海子组三级层序的高位体系域内,地貌高地的台内滩部位较易发育白云岩化储层和淡水淋滤储层。

In the western Maigaiti area in the Tarim Basin,the Carboniferous oil and gas reservoirs discovered in the Bashituo and Yasongdi areas showed a good prospect lor hydrocarbon exploration. However,their development models are not clear. Unconformity characteristics were analyzed through seismic and drilling/logging stratigraphic comparison, and reservoir development features were studied combing core and seismic data. The western Maigaiti area uplifted and was eroded during the Bachu Movement in the Late Carboniferous,forming two unconformities including Tj（between the Kalashayi and Xiaohaizi formations） and Tjj（ between the Xiaohaizi and Nanzha formations）. The Tj unconformity is a tectonic unconformity,and mainly formed karst geomorphologies such as uplift,slope and valley. It developed two karst systems, the vadose zone and shallow undercurrent belt, and the deep undercurrent belt. Favorable reservoirs mainly locate on karst slopes. The T; unconformity is a stratum unconformity controlled by paleotopography and eustatic movement. Dolomitic reservoirs and fresh water leaching reservoirs developed in intraplat-form shoal with high landform in the highstand system tract in the Xiaohaizi Formation.