摘要
川西新场气田下沙溪庙组主要为三角洲、湖泊沉积,砂岩通常呈南北向条带状分布在新场地区的东西两个区域,分布范围较上沙溪庙组砂岩小,但在东部地区仍具有较大厚度(20 m^35 m)。下沙溪庙组储层平均孔隙度10.7%,平均渗透率0.15×10-3μm2,属于低-中孔、特低渗非均质储层。与目前构成沙溪庙组气藏主体的上沙溪庙组砂岩比较(平均孔隙度9.4%,平均渗透率0.145×10-3μm2),下沙溪庙组(特别是Js31储层)具有较高孔隙度、较好孔隙结构和近似的渗透率,裂缝相对不发育。储层主要为岩屑长石砂岩和长石岩屑砂岩,孔隙类型以粒间溶蚀扩大孔、剩余粒间孔和粒内溶孔为主。沉积微相是影响新场地区下沙溪庙组储层储集性的最主要因素,优质储层主要分布在分流河道(特别是河道主体部位)砂岩中。同时,储层储集性也明显受到岩石组构、成岩作用的影响。位于东、西分流河道主体部位的中粒高长石、低岩屑、低碳酸盐胶结物、低粘土矿物的砂岩具有最佳的储渗性。
In contrast to the laterally continuous blanket-like reservoirs in the Upper Shaximiao Formation（Js1＋2）,the Lower Shaximiao（Js3） lacustrine-delta ribbon sandstones with the thickness of 20 m~ 35 m in the Xinchang gas field exhibit limited lateral continuity and were deposited with dominant paleo-currents from north to south.The Lower Shaximiao reservoirs are characterized by low-medium porosity（av.10.7%）,very low permeability（av.0.15 mD）,and strong heterogeneity with reservoir characteristics better than the upper Shaximiao sandstones and with less developed fractures.Reservoirs are composed of lithic arkoses and feldspathic litharenites,and the dominant types of porosity include secondary porosity（intergranular and intragranular）,and primary intergranular porosity.Micro-facies played a critical role in the formation of the Lower Shaximiao sandstone reservoirs and high-quality reservoirs are mainly found in channel sandstones（especially in the main body of the channel）.The diagenesis and the occurrence of micro-fractures also make great impact on reservoir quality.Medium-grained fluvial channel sandstones with high feldspar content,low lithoclast,carbonate cement,and clay content are of highest porosity and permeability.
出处
《矿物岩石》
CAS
CSCD
北大核心
2010年第3期96-104,共9页
Mineralogy and Petrology
基金
国家科技重大专项(2008ZX05002-004)
关键词
新场气田
下沙溪庙组
致密砂岩
储层
影响因素
Xinchang gas field
Lower Shaximiao Formation
tight reservoir
reservoir quality
influencing factors
