和田河气田奥陶系碳酸盐岩储层特征及建设性成岩作用

CARBONATE ROCK RESERVOIR AND CONSTRUCTIVE DIAGENESIS OF ORDOVICIAN IN HETIANHE GAS FIELD,TARIM BASIN

和田河气田是塔里木油田分公司“九五”期间探明的大型气田。该气田的主要储层是奥陶系碳酸盐岩 ,储集空间主要包括孔隙、溶洞和裂缝。对储层控制作用最强的是岩溶作用和破裂作用等建设性成岩作用。由于风化淋滤作用和构造运动产生的构造裂缝的改造 ,在奥陶系古潜山出现了较好的风化壳岩溶并使溶蚀孔洞十分发育。溶蚀孔隙的存在大大增加了储层的孔隙度 ,该储层约78%的孔隙为溶蚀孔隙。通过切割关系、裂缝充填物的宏观和微观特征可识别出 5期构造裂缝。裂缝孔隙度占总孔隙度的 1 .5 %～ 3.5 % ,但裂缝渗透率却占总渗透率的 99.4%左右。

Hetianhe gas field, a large scale carbonate gas pool proved by Branch Company of Tarim Oilfield during the ninth five year plan. The carbonate rock of Ordovician is the principal reservoir. Porosity, cavern and fracture are the dominant types of the reservoir space. Because of exposuring to the land surface for a long time, the reservoir experienced weathering and leaching, alteration of structure factures by tectonic motions, formed developed weathered crust karst. Two types of constructive diagenesis controlling to reservoir capacity greatest are karstification and facture. The porosity of the reservoir is increased great for the occurrence of solution pores. About 78% of the pores are solution pores. According to intersect relation of the rift, macro and micro characteristics of the crack filler in the factures, five periods of struture factures are recognized. The porosity of facture make up 1.5%~3.5% of total porosities, and the permeability make up 99.4% or so.