摘要
地层水的形成与分布与油气的生成、运聚及油气藏的形成、保存和破坏有着密切的关系。对川中凹陷多个钻井须家河组地层水化学特征的分析表明:研究区须家河组以CaCl水型为主,须二段还发育NaHCO、MgCl水型;地层水矿化度整体较低,须二段矿化度多小于10 g·L^(-1),须四段矿化度集中在40~60 g·L^(-1);须二段地层水的钠氯系数在0.051~1.72之间,平均值为0.66;须四段地层水钠氯系数分布在0.40~0.53之间,平均值为0.48,这说明两者属于高浓缩变质水,油气保存好。纵向上川中凹陷地层水分布具有明显的分段性,整体呈现“增大-减小-增大”的趋势,其中K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)、Cl^(-)、HCO_(3)^(-)、CO_(3)^(2-)、变质系数、钠氯系数与TSD趋势一致,但脱硫系数与TSD趋势相反,川中凹陷须家河组地层水垂向上可以划分为两个大的旋回(A→B为泥岩压实排水→渗流浓缩;C→D为泥岩压实排水→越流浓缩带)。研究区内地层水在平面上具有明显分分区性,其中成都凹陷、龙门山推覆带矿化度较低,发育大气水下渗向心流,而安县-鸭子河-大邑断褶带南部、孝泉-丰谷构造带东部、知新场-龙宝梁构造带西部矿化度较高,变质系数较低,说明该地区天然气保存良好。通过对川中凹陷须家河组地层水化学特征及分布规律的研究,明确了该区地层水成因及特征,为下一步油气保存条件的研究提供了依据。
The formation and distribution of formation water are closely related to the generation, migration and accumulation of oil and gas,as well as the formation, preservation and destruction of oil and gas reservoirs. The analysis of formation hydrochemical characteristics of Xujiahe formation in several drilling wells in Central Sichuan depression shows that: the Xujiahe formation in the study area is dominated by CaClwater type, and NaHCOand MgClwater types are also developed in the second member of Xujiahe formation;The salinity of formation water is relatively low as a whole, and the mineralization of XU section II is mostly less than 10 g·L^(-1), and the mineralization of XU Section IV is concentrated in 40 ~ 60 g·L^(-1) The sodium chloride coefficient of formation water in XU section II is between 0.051 and 1.72, with an average value of 0.66;The sodium chloride coefficient of formation water in XU Section IV is distributed between 0.40 and 0.53, with an average value of 0.48, which indicates that they belong to highly concentrated metamorphic water and oil and gas are well preserved. Vertically, the distribution of formation water in Chuanzhong sag is obviously segmented, and the overall trend is "increase-decrease-increase". Among them,the trend of K^(+),Na^(+), Ca^(2+),Mg^(2+),Cl^(-),HCO_(3)^(-),CO_(3)^(2-), metamorphic coefficient and sodium-chloride coefficient are consistent with TSD trend, but the desulfurization coefficient is opposite to TSD trend. The formation water of Xujiahe Formation in Central Sichuan depression can be divided into two major cycles vertically: a→B is mudstone compaction and drainage → seepage concentration;C →D is mudstone compaction and drainage→ overflow concentration zone. The formation water in the study area has obvious zoning on the plane. Among them, the mineralization of Chengdu sag and Longmenshan nappe zone is low, and atmospheric water infiltration centripetal flow is developed. However, the south of Anxian-Yadehe-Dayi fault fold belt, the east of Xiaoquan-Fenggu structural belt and the west of Zhixinchang-Longbaoliang structural belt have high mineralization and low metamorphic coefficient, indicating that the natural gas in this area is well preserved. Through the study on the formation water chemical characteristics and distribution law of Xujiahe Formation in Central Sichuan depression, the genesis and characteristics of formation water in this area are clarified, which provides a basis for the further study of oil and gas preservation conditions.
作者
张雷
罗谋兵
文健安
ZHANG Lei;LUO Mou-bing;WEN Jian-an(Geological Exploration and DEVELOPMENT Research Institute of Chuanqing Drilling Engineering Co.,Ltd.,Chengdu Sichuan 610051,China)
出处
《当代化工》
CAS
2022年第6期1416-1419,1424,共5页
Contemporary Chemical Industry
基金
国家自然科学基金项目,致密油储层低摩阻纳米磁流体压裂液构筑及渗吸驱油机制(项目编号:51874334)
国家科技重大专项专题,超低渗油藏力学作用机制及渗流数学模型(项目编号:2019ZX05013-001-004)。
关键词
地层水
化学特征
分布规律
Formation water
Hydrochemical characteristics
Distribution law
