川北大安寨生屑灰岩储层主控因素及预测思路

Major Controlling Factors and a Method for Predicting Bioclastic Limestone Reservoirs in Da'anzhai, Northern Sichuan

王伟东 彭军 夏青松 段冠一 孙恩慧

WANGWeidong PENGJun XIAQingsong DUANGuanyi SUNEnhui

中国石油大庆油田有限责任公司采油工程研究院, 黑龙江 大庆 163712 西南石油大学地球科学与技术学院, 四川 成都 610500 中国石油东方地球物理公司大庆物探二公司, 吉林 松原 138000 中海石油(中国)有限公司渤海石油研究院, 天津 塘沽 300459

Production Engineering&Research Institute, Daqing Oilfield, CNPC, Daqing, Heilongjiang 163712, China School of Geoscience and Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China Daqing No.2 Company, Bureau of Geophysical Prospecting INC., CNPC, Songyuan, Jilin 138000, China Exploration and Development Research Institute, Bohai Oilfield, CNOOC China Limited, Tanggu, Tianjin 300459, China

为明确川北地区大安寨段湖相生屑灰岩储层发育的特点及主控因素，寻找有利储层发育区，综合钻井岩芯描述、薄片鉴定、扫描电镜观察、测试分析等手段，开展区内沉积学、储层特征研究。研究结果认为，川北地区大安寨段为浅湖-半深湖相沉积，浅湖亚相发育介屑滩、滩间洼地、浅湖泥微相，半深湖亚相发育滩前湖坡、半深湖泥微相；储层岩石类型以介屑灰岩为主，储层物性总体较差，平均孔隙度为1.18%，渗透率普遍小于1 mD，具有特低孔、特低渗的特征；储集空间类型主要为溶蚀孔、洞和裂缝。储层类型以孔隙裂缝型储层为主，裂缝孔隙型储层及裂缝型储层均有发育。以此为依据，分析并探讨了湖相生屑灰岩储层发育的控制因素，认为有利沉积相带、建设性成岩作用、裂缝系统控制了大安寨段储层的发育。结合大安寨各层段地层特点提出了有针对性的储层预测思路。

The aim of this study was to clarify the characteristics and major factors controlling the formation and development of bioclastic limestone reservoirs in the lake facies of the Da'anzhai Member in Northern Sichuan, and to search for favorable reservoir development zones. Through drilling core description, thin slice identification, scanning electron microscope observation and test analysis, we performed a study on the sedimentology and reservoir characteristics in the area. According to our findings, the Da'anzhai Member in Northern Sichuan Basin is a shallow-lake-semi-deep-lake facies deposit. In the shallow-lake subfacies develops the bioclastic beaches, inter-beach depressions, and shallow-lake mud micro-facies, whereas in the semi-deep lake subfacies develops the beachfront lake slope and semi-deep lake mud micro-facies. Dominated by bioclastic limestone the reservoir is poor overall physical properties and is characteristic of ultra-low porosity and ultra-low permeability with average porosity of 1.18%, permeability less than 1 mD. The types of reservoir space are mainly corrosion pores, holes, and cracks. The predominant reservoir type is pore-fractured, while fracture-porosity reservoirs and fracture-type reservoirs also developed in the study area. Based on the results and analyses, the factors controlling the development of lake-facies bioclastic limestone reservoirs are discussed. We believe that favorable sedimentary facies belts, constructive diagenesis, and the fracture system control the development of reservoirs in the Da'anzhai Member. Finally, we propose a targeted reservoir prediction method based on the stratigraphic characteristics of each layer in the Da'anzhai Member.

10.11885/j.issn.1674-5086.2019.03.04.06