塔河油田4区古地貌对储层分布的影响

Control of paleogeomorphology on reservoir distribution in Block 4 of Tahe oilfield

碳酸盐岩储层预测一直为世界性难题。塔河油田4区奥陶系碳酸盐岩储层以岩溶、构造运动形成的溶蚀孔洞和裂缝系统为主,具有埋藏深,非均质性强的特点。基于三维地震资料,通过构造的精细解剖,认识到断层纵横向展布控制油气成藏,断裂发育的地区溶蚀孔洞发育;通过对中-下奥陶统顶部海西早期岩溶古地貌的恢复,发现塔河4区奥陶系潜山储层分布主要受岩溶古地貌影响,并明确了缝洞储层有利发育区。综合分析认为,在后期开发方案调整中应该避开古地形低洼区;而在储层精细描述中,应根据古地貌特征调整属性预测参数。通过古地貌恢复,为油藏精细方案调整和有效开发奠定了基础。该思路和方法对塔河油田其它相似区块的研究和寻找奥陶系油气高产区具有借鉴意义。

Prediction of carbonate reservoirs is challenging all over the world.The reservoir spaces of the Ordovician carbonates in Block 4 of Tahe oilfield are dominated by dissolved vug and fracture systems developed from karstification and tectonic movement.These reservoirs feature in deep burial and high heterogeneity.Fine structural interpretation with 3D seismic data reveals that hydrocarbon accumulation is controlled by vertical and horizontal fault distribution,and the dissolved vugs are well associated with faults.Restoration of the Early Hercynian karst paleogeomorphology on the top of Middle-Lower Ordovician in Tahe oilfield indicates that the distribution of the Ordovician buried-hill reservoirs in Block 4 of Tahe oilfield is mainly controlled by the karst paleogeomorphology.The areas favorable for the development of fractured-vuggy reservoirs are delineated.Comprehensive analysis shows that the low-lying areas of the ancient terrain should be avoided in the latter development plan refinement,and parameters for fine reservoir description should be adjusted according to the palaeogeomorphology characteristics.Paleogeomorphology restoration lays a basis for reservoir plan refinement and effective development.This method is helpfull for the study of other similar blocks and the discovery of highly productive Ordovician reservoirs in Tahe oilfield.