鲁西豫东地区奥陶系顶部岩溶储集层特征及有利控制因素

摘要

基于野外露头、岩心、薄片和测录井等地质及地球物理资料分析，并结合区域地质背景，深入研究了鲁西豫东（东濮）地区奥陶系顶部峰峰组和上马家沟组岩溶储集层发育特征、演化过程，并进一步分析优质储集层形成的主控因素，预测了有利储集层分布区。结果表明，奥陶系顶部储集层主要岩性为颗粒石灰岩、云质石灰岩、泥晶石灰岩、粉细晶白云岩、含膏白云岩和藻粘结白云岩等，裂缝和溶洞是主要储集空间类型。白云岩类储集层平均孔隙度为2.5％，平均渗透率为7.43×10－3μm 2；石灰岩类储集层平均孔隙度为2.2％，平均渗透率为2.72×10－3μm 2。储集层经历了沉积—准同生期成孔（寒武纪—中奥陶世）→风化淋滤（晚奥陶世—早石炭世）→矿物充填（晚石炭世—白垩纪末期）→溶蚀改造（古近纪）4个演化阶段。沉积相、成岩作用及构造应力控制了研究区优质储集层的形成。颗粒滩及潮坪相带、断裂发育带、白云石化作用和准同生岩溶、表生岩溶、埋藏岩溶作用6项叠合区储集层质量最优；颗粒滩及潮坪相带、白云石化作用和准同生岩溶作用、表生岩溶作用4项叠合区，以及断裂发育带、表生岩溶作用、埋藏岩溶作用3项叠合区储集层质量次之；颗粒滩及潮坪相带、断裂发育带、白云石化作用和准同生岩溶作用、埋藏岩溶作用5项叠合区储集层质量一般。%Based on observation of outcrops,cores and thin sections and analysis of logging data, combined with regional geological background,features,evolution,main controlling factors of the reser-voir within the Fengfeng Formation and Majiagou Formation,the uppermost part of Ordovician in the west-ern Shandong-eastern Henan (Dongpu)area were studied deeply.Subsequently,the distribution of fa-vorable reservoirs was predicted.The study results revealed that grain limestone,dolomitic limestone,mi-crite limestone,silty-fine crystalline dolostone,gypsum-bearing dolostone and algae dolostone were the dominant rock types,and the main reservoir spaces were cracks and pores.The average porosity of dolo-mite reservoirs was 2.5%,and the average permeability was 7.43×1 0 -3μm 2 .The average porosity of lime-stone reservoir was 2.2%,and the average permeability was 2.72 ×1 0 -3 μm 2 .The reservoirs had experi-enced four evolution stages,which are the period of penecontemporaneous pore formation (Cambrian-Mid-dle Ordovician),weathering leaching period (Late Ordovician-Early Carboniferous),minerals filling pe-riod (Late Carboniferous -Late Cretaceous) and the period of pore dissolution reconstruction (Paleo-gene).Sedimentary facies,diagenesis and tectonic stress play a significant role in controlling the formation of favorable reservoirs.The study indicates that areas superimposed by the grain bank,tidal flat facies zone,fault belt,dolomitization area,penecontemporaneous karstification area,epigenic karstification ar-ea and buried karstification area are predicted as the most favorable reservoir zone.Areas superimposed by the grain bank,tidal flat facies zone,dolomitization area,penecontemporaneous karstification area,epi-genic karstification area and areas superimposed by the fault belt,epigenic karstification area,buried karstification area are predicted as the secondary favorable reservoir zones.Areas superimposed by the grain bank,tidal flat facies zone,fault belt,dolomitization area,penecontemporaneous karstification area and buried karstification area are predicted as the general reservoir zone.