四川盆地川西坳陷新场须家河组二段气藏甜点模式及形成机理  

Gas pool sweet spot models and their forming mechanism in the Xu 2 Member in Xinchang area,Western Sichuan Depression,Sichuan Basin

作　　者：刘君龙 胡宗全[1] 刘忠群 金武军[1] 肖开华[1] 毕有益[2] 李吉通 Liu Junlong;Hu Zongquan;Liu Zhongqun;Jin Wujun;Xiao Kaihua;Bi Youyi;Li Jitong(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;Southwest Oil&Gas Branch Company,SINOPEC,Chengdu,Sichuan 610081,China)

机构地区：[1]中国石化石油勘探开发研究院,北京100083 [2]中国石化西南油气分公司,四川成都610081

出　　处：《石油与天然气地质》2021年第4期852-862,共11页Oil & Gas Geology

基　　金：国家科技重大专项(2016ZX05002-006);中国石化科技部项目(P18089-4)。

摘　　要：致密砂岩气藏甜点评价是储量有效动用的关键。基于四川盆地川西坳陷新场须家河组二段气藏精细解剖,阐明了气藏甜点地质特征,建立了气藏甜点模式和识别标准,明确了甜点空间分布特征,探讨了致密气藏甜点形成机理。结果表明:①有效储层划分为两种类型,分别为平缝发育的中-粗粒砂岩和块状层理的中粒砂岩,且有效裂缝为倾角大于30°的构造缝;②气藏甜点可以划分3种类型,分别为断缝型、层理缝型和孔隙型甜点,断缝型甜点高角度裂缝较发育,主要分布在SN向断裂所控制的断缝体内,层理缝及孔隙型甜点高角度缝不发育,主要分布在断缝体之外的优质储层内;③构造位置较高的有利含气区是新场须二段气藏甜点发育的基础,晚期断裂影响的断缝体决定了断缝型甜点的形成,在断缝体之间,优质储层品质是层理缝及孔隙型甜点形成的主要控制因素。明确气藏甜点模式,阐明甜点形成机理,一方面可以深化致密气藏甜点理论认识,另一方面也可以为甜点分布预测和可动储量评价提供有力支撑。Sweet spot evaluation of the tight sandstone reservoirs is of great importance to effectively developing reserves.The elaborate description of the gas pools in the 2 ^(nd) member of Xujiahe Formation(Xu 2 Member/T_(3) x^(2)),serves to establish the sweet spot model and formulate the criteria for identification,and clarify the geological distribution of the sweet spots.Furthermore,the forming mechanism of the sweet spots in tight sandstone gas pools is discussed.The results show that:(1)the effective reservoirs can be grouped into two categories,namely the medium-to-coarse-grained sandstone with flat fractures(with a dip angle less than or equal to 10°),and the massive medium-to-coarse-grained sandstone;the effective fractures are structural fractures with a dip angle greater than 30°.(2)The sweet spots can be classified into three categories,namely the fault-,bedding fissure-,and pore-dominated categories.The first one is characterized by high dip angle fractures,mainly developed in the fault-fracture body dominated by SN-oriented faults;the last two are characterized by less developed high dip angle fractures,mainly distributed in high-quality formations outside of the fault-fracture body.(3)Gas-bearing zones of relatively high tectonic position serve as the basis factor for the sweet spot development in T_(3) x^(2),the fault-fracture body affected by later faulting is a major factor controlling sweet spot growth,and the quality of favorable formations controls the formation of the other two categories.In all,it is of great significance to building the sweet spot models and identifying its forming mechanism for the gas pools,which could deepen our understanding on the sweet spot-related theories of tight sandstone gas pools,and is of strong support to the sweet spot distribution prediction and movable reserves evaluation.

关 键 词：甜点模式 评价标准 断缝体 优质储层 致密砂岩气藏 须家河组 四川盆地 

分 类 号：TE122.3[石油与天然气工程—油气勘探]