苏里格气田S120区块地层水成因及气水分布主控因素

Origin of Formation Water and Main Controlling Factors of Gas-Water Distribution in S120 Block of Sulige Gasfield

苏里格气田西区S120区块部分气井含水层多、产水量大,为了查明地层水成因及气水分布主控因素不明确等制约气田开发的关键问题,统计分析S120区块测井、试气、地层水化学等资料,观察岩石薄片、进行综合研究。结果表明:(1)区内气藏地层水矿化度高,弱酸性,水型为CaCl2;(2)地层封闭性强,天然气保存良好;(3)地层水以与外界隔绝的残余水和变质的古沉积水为主;(4)按照地层水的空间分布可将地层水分为构造低部位水(Ⅰ型)、低渗带滞留水(Ⅱ型)、孤立透镜体水(Ⅲ型)3种类型。研究认为:生烃强度、源储距离、砂体展布、储层物性及现今构造共同控制了S120区块气水分布,其中现今构造、生烃强度和砂体展布控制了气、水的整体分布格局,是气水分布的主控因素;天然气富集于物性良好的主河道部位,地层水主要分布于储层物性较差的河道边缘。

Some gas wells in S120 block of west Sulige gas field have many aquifers and large water production.The key problems restricting gas field development,such as genesis of formation water and main control factors of gas-water distribution are comprehensively studied through statistical analysis of logging,gas testing and formation water chemistry data of S120 block and observation of rock thin sections.The results show that,(1)The gas reservoir formation water in the study area is highly mineralized and weakly acidic,belonging to CaCl2 water type;(2)The formation is highly sealed and natural gas is well preserved;(3)The formation water is mainly the residual water isolated from the outside world and metamorphic paleosedimentary water;(4)According to the spatial distribution of formation water,it can be divided into three types:structural low position water(type I),retained water in low permeability zone(type II)and isolated lens water body(type III).Hydrocarbon generation intensity,source-reservoir distance,sand body distribution,reservoir physical properties and current structure jointly control the gas and water distribution in block S120,among which the current structure,hydrocarbon generation intensity and sand body distribution control the overall distribution pattern of gas and water and they are the main control factors of gas and water distribution;natural gas is concentrated in the main river channel with good physical properties,and formation water is mainly distributed in the channel edge with poor physical properties.