Characteristics and genesis of the Feixianguan Formation oolitic shoal reservoir, Puguang gas field, Sichuan Basin, China

作     者：Peiyuan CHEN Xiucheng TAN Huiting YANG Ming TANG Yiwei JIANG Xiuju JIN Yang YU 

作者机构：State Key Laboratory of Oil and Gas Geology and Exploration Southwest Petroleum University Chengdu 610500 China School of Geoscience and Technology Southwest Petroleum University Chengdu 610500 China Research Institute of Petroleum Exploration and Development SINOPEC Zhongyuan Oilfield Company Puyang 457001 China 

出 版 物：《Frontiers of Earth Science》 (地球科学前沿（英文版）)

年 卷 期：2015年第9卷第1期

页      面：26-39页

核心收录：

学科分类：0820[工学-石油与天然气工程] 081801[工学-矿产普查与勘探] 081802[工学-地球探测与信息技术] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 0704[理学-天文学] 082002[工学-油气田开发工程] 

基　　金：supported by the Major State Basic Research Development Program China's National Science & Technology Special Project the PetroChina Research Fund the Key Subject Construction Project of Sichuan Province, China Dr. Jian Cao at Nanjing University is thanked for his enthusiastic support and collaboration during this project 

主　　题：oolite shoal reservoir carbonate diagenesis,Triassic Feixianguan Formation Puguang gas field Sichuan Basin 

摘      要：The Lower Triassic Feixianguan Formation at the well-known Puguang gasfield in the northeastern Sichuan Basin of southwest China produces a representa- tive oolitic reservoir, which has been the biggest marinesourced gasfield so far in China （discovered in 2003 with proven gas reserves greater than 350× 10^8 m3）. This study combines core, thin section, and scanning electron microscopy observations, and geochemical analysis （C, O, and Sr isotopes） in order to investigate the basic characteristics and formation mechanisms of the reservoir. Observations indicate that platform margin oolitic dolomites are the most important reservoir rocks. Porosity is dominated by intergranular and intragranular solution, and moldic pore. The dolomites are characterized by medium porosity and permeability, averaging at approximately 9% and 29.7 mD, respectively. ^87Sr/^86Sr （0.707536-0.707934） and δ^13CpDB （1.8 ‰--3.5 ‰） isotopic values indicate that the dolomitization fluid is predominantly concentrated seawater by evaporation, and the main mechanism for the oolitic dolomite formation is seepage reflux at an early stage of eodiagenesis. Both sedimentation and diagenesis （e.g., dolomitization and dissolution） have led to the formation of high-quality rocks to different degrees. Dolomite formation may have little contribution, karst may have had both positive and negative influences, and burial dissolution-TSR （thermochemical sulfate reduction） may not impact widely. The preservation of primary intergranular pores and dissolution by meteoric or mixed waters at the early stage of eogenesis are the main influences. This study may assist oil and gas explorationactivities in the Puguang area and in other areas withdolomitic reservoirs.