川中南部地区中三叠统雷口坡组顶部古岩溶储层研究  

PALAEOKARST RESERVOIR RESEARCH OF THE MIDDLE TRIASSIC LEIKOUPO IN THE SOUTH AREA OF CENTRAL SICHUAN BASIN

作　　者：汪华[1] 刘树根[1] 王国芝[1] 张长俊[1] 秦川[1] 邱文彬[2] 

机构地区：[1]成都理工大学"油气藏地质及开发工程"国家重点实验室,四川成都610059 [2]中石油西南油气田分公司川中油气矿研究所,遂宁629000

出　　处：《物探化探计算技术》2009年第3期264-270,177,共7页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：中国石油西南油气田分公司川中油气矿课题(XNS06JS2006.083)

摘　　要：川中南部地区中三叠统雷口坡组沉积后,存在一个抬升剥蚀阶段,与上覆上三叠统须家河组成区域性平行不整合接触。通过岩心观察和薄片鉴定,可确定该工区在退后生期有岩溶作用,主要表现为岩溶角砾岩、去膏化、去白云石化、硅化和溶孔、溶缝的形成,还可见渗流带的产物—渗流豆石。通过对δ13C、δ18O、87Sr/86Sr比值等地球化学指标的分析,发现雷口坡组顶部存在一个地球化学跃变带,与典型古岩溶界面的地球化学特征可以类比。测井解释表明,该工区古岩溶局部发育。但雷口坡组顶部原有的大部份溶蚀孔洞缝被后期成岩作用破坏(被泥质不同程度充填),影响了油气的运移和聚集。通过分析认为,应对该层位进行加深研究,对保存较好的,但目前勘探程度较低的古岩溶有利区块地区加以重视。After the Leikoupo stratum of Middle Triassic had been deposited in the south area of central Sichuan, it was uplifted and eroded. Its contact surface with the Xujiahe formation of Upper Triassic is a regional accordant unconformity. We confirm in this paper that there is karstification in this area by core sample observation and rock thin-section analysis.The main display is the development of karst breccia,degypsum,dedolomitization,silication,dissolved pore and cracking.The product of vadose zone, infiltration pisolite, can also be found. By means of analysis of the geochemical index,such as δ13C,δ18O,87Sr/86Sr etc, we find that there is a geochemical jump zone on the top of Leikoupo formation. Its geochemical feature can be compared with the typical palaeokarst interface.The well log interpretation shows that the palaeokarst developed locally in this area. But the most original corrosion holes and cracks of the top of Leikoupo formation had been destroyed by the later stage of diagenesis. Through the analysis, we think that this formation should be further studied, and that we should focus on the area where the palaeokarst is kept but the degree of exploration is lower at present.

关 键 词：雷口坡组 三叠系 不整合面 古岩溶 四川盆地 

分 类 号：P542.34[天文地球—构造地质学]