摘要
文章介绍了一类准同生期云化叠合早期暴露岩溶成因的深层—超深层孔洞型碳酸盐岩储层。基于区内露头与钻井资料,开展了岩石学、储层地质学及地球化学研究,发现四川盆地中二叠统栖霞组发育泥晶灰岩—生屑泥晶灰岩—泥亮晶颗粒灰岩的向上变粗型和亮晶颗粒云岩—中晶云岩—细粉晶藻云岩的向上变细型两类向上变浅序列。两类序列早期高频暴露岩溶具有如下特征:①旋回顶部存在暴露不整合面,并见下一旋回初始海泛沉积物充填于先期岩溶系统和向微地貌高地超覆现象。②旋回上部的多孔基岩受优势岩溶通道切割形成近原地角砾。③部分旋回顶部发育斑块状岩溶系统,其内为陆源黏土、粉屑和少量角砾充填。④少数旋回内部发育岩溶洞穴角砾岩,角砾间多为碳酸盐岩渗流粉砂充填。⑤暴露面之下稳定碳、氧同位素存在一定负偏现象。进一步开展储层物性分析发现,岩溶作用强度较强时,优质储层主要发育于旋回的下部,储层储集空间主要为基岩保留的粒间孔经过云化与溶扩而形成的小型孔洞;岩溶作用强度较弱时,优质储层主要发育于旋回的中上部,储层储集空间为基岩保留的粒间孔经过云化与溶扩而形成的小型孔洞;岩溶作用强度适中时,优质储层主要发育于旋回的中部,储层储集空间主要为洞穴垮塌角砾间的残余孔洞。这些叠合准同生期云化作用的白云岩为基岩的早期暴露岩溶作用形成的孔洞至今仍然被保留下来,并作为有效储集空间。因此认为不同强度的早期高频暴露岩溶作用是栖霞组储层储集空间形成的主要因素。
The paper presents a set of deep to ultra-deep vuggy carbonate reservoirs with genesis of penecontemporaneous dolomitization superposing with early-stage exposed karstification.Based on outcrops and drilling data in the study area,researches have been carried out on petrology,reservoir geology and geochemistry.And 2 types of shallowing-upward sequence have been identified in the Qixia Formation of Middle Permian in the Sichuan Basin.The first is the coarsening-upward type from micrite to bioclastic micrite to micrite-sparry grain limestone.And the second is the fining-upward type from sparry grain dolomite to medium-crystalline dolomite to fine-powder crystalline dolomitized microbialite.The early high-frequency exposed karstification of both types has the following characteristics:(1)There are exposed unconformities at the top of the cycles.And the initial flooding sediment of the next cycle was filled in the earlier karst system and overlapping to the micro paleo-geomorphic highs.(2)The vuggy bedrocks in the upper part of the cycle were cut by the dominant karst channels and formed near in-situ breccias.(3)The patch-like karst systems are developed at the top of some cycles,which was filled with terrigenous clay,silty clasts and some breccias.(4)Karst cave breccias are developed in some cycles,and the inter-breccia caves were filled with carbonate vadose silts.(5)The stable carbon and oxygen isotopes are some certain of negative under the exposure surface.Further study on reservoir physical properties shows that,when karstification is relatively strong,high-quality reservoirs are mainly developed in the lower part of the cycle,and the reservoir space is mainly small vugs formed by dolomitization and dissolution expansion of the intergranular pores preserved in bedrocks.When the karstification is relatively weak,the high-quality reservoirs are mainly developed in the middle and upper part of the cycle,and the reservoir space is as the former.When the intensity of karstification is moderate,the high-quality reser
作者
李明隆
谭秀成
罗冰
张亚
张本健
芦飞凡
苏成鹏
肖笛
钟原
Li Minglong;Tan Xiucheng;Luo Bing;Zhang Ya;Zhang Benjian;Lu Feifan;Su Chengpeng;Xiao Di;Zhong Yuan(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University;Southwest Petroleum University Division of CNPC Key Laboratory of Carbonate Reservoirs;Research Institute of Exploration and Development,PetroChina Southwest Oil and Gasfield Company;Branch of Chuanxibei Gas Field,PetroChina Southwest Oil and Gasfield Company;Key Laboratory of Surficial Geochemistry,Ministry of Education,Nanjing University)
出处
《中国石油勘探》
CAS
CSCD
北大核心
2020年第3期66-82,共17页
China Petroleum Exploration
基金
国家自然科学基金项目“四川盆地栖霞组非均质砂糖状白云岩交织共生与储层形成机理”(41802147)。
关键词
早期高频暴露岩溶
深层—超深层
孔洞成因
四川盆地西北部
中二叠统
栖霞组
early high-frequency exposed karstification
deep to ultra-deep
genesis of vugs
northwest Sichuan Basin
Middle Permian
Qixia Formation
