东营凹陷平方王-平南潜山下古生界碳酸盐岩储层成因及分布模式

Origin and distribution model of the lower Paleozoic carbonate reservoirs in Pingfangwang-Pingnan buried hills, Dongying Sag

关键词:  平方王-平南潜山  下古生界  碳酸盐岩  储层成因  分布模式

Key words:  Pingfangwang-Pingnan buried hills  the lower Paleozoic  carbonate rocks  origin of reservoirs  distribution model

摘要:

鉴于渤海湾盆地下古生界碳酸盐岩储层分布和成因的复杂性及其对油气勘探的重要性,以东营凹陷平方王-平南潜山下古生界碳酸盐岩储层为研究对象,以丰富的钻井岩心及生产数据为基础,综合利用岩心常规物性分析、薄片鉴定及元素地球化学等技术手段,明确研究区碳酸盐岩潜山储集特征及成因,并建立储层分布模式。结果表明:研究区下古生界碳酸盐岩为次生孔、洞和裂缝主导的储层,表生岩溶作用、断裂作用、岩浆侵入作用等共同造成了研究区内储层复杂的成因及分布;残丘山遭受加里东期及燕山—喜山期两期表生岩溶,形成了潜山顶部孔-洞-缝型储层,而在潜山底部岩浆侵入引发的裂缝及溶蚀孔形成了潜山内幕孔-缝型储集体;对于断块型潜山而言,潜山顶部孔-洞-缝复合型储层为断裂破碎作用或断裂破碎作用与加里东期表生岩溶相叠加的结果,下部则以诱导裂缝带及岩浆侵入形成的裂缝为主导,伴生有微弱溶蚀,形成内幕孔-缝型储层。

Abstract:

In view of the complexity of both the distribution and origin of the lower Paleozoic carbonate reservoirs in the Bohai Bay Basin as well as its importance to hydrocarbon exploration, the characters and origin of the lower Paleozoic carbonate reservoirs of Pingfangwang-Pingnan buried hills in Dongying Sag were studied using drilling cores and production data as well as a combination of conventional petrophysical property analysis, thin section analysis and element geochemistry. The distribution model of the reservoirs was established accordingly. The results show that the reservoirs are dominated by secondary pores, caves and fissures. The complex origin and distribution of the reservoirs resulted from a combination of several geological processes, such as epikarst, faulting and magma intrusion. The monadnock-type buried hills experienced two generations of epikarst which took place in the Caledonian and Indosinian-Yanshan stages, resulting in the pore-cave-fissure compound reservoirs at the top of the buried hills. Meanwhile, the magma intrusion at the lower part and accompanied dissolution led to pore-fissure type inner reservoirs. As for the fault block buried hills, the fracturing effect of fault or its combination with the Caledonian stage epikarst caused pore-cave-fissure compound reservoirs at the top of the buried hills. The lower part is characterized by induced joints caused by faults or magma intrusion with a small portion of dissolution, forming pore-fissure type inner reservoirs.