断层泥比率(SGR)三维模型定量表征断层封闭性分析

Shale Gouge Ratio (SGR) 3D Model for Quantitative Characterization of Fault Seal Analysis

摘要: 断层封闭性既是地下储气库建库阶段需要重点分析的建库条件与储气库运行期间的重要安全指标，同时也是达容达产的地下储气库进行增压扩容时应该进行研究的重要部分。本文以板南区块白6储气库为例，分析储气库断层分布特征，通过三维地质模型，将断层两端地层属性投影至断层模型上，建立断层泥比率(SGR)三维模型，从而对断层封闭性进行定量表征，并与基于数据计算的断层泥比率(SGR)结果进行对比。结果表明：研究区断层封闭主要为岩性对接封闭与断层岩封闭中的泥岩涂抹封闭。断距较大的F1、F4、F5断层两盘砂泥对接，封闭性较好；F3断层断距较小，断层两端砂泥对接、砂砂对接、泥泥对接三种情况均存在，泥比率整体均在50%之上，封闭性较好；F8断层断距较小，断层两端以泥泥对接、砂泥对接为主，少量位置砂砂对接，泥比率在20%以上，多数位置处于40%以上，封闭性较好；F9断层两侧地层以泥泥对接为主，其中砂泥对接区域泥比率整体在15%左右，封闭性较差。

Abstract: Fault sealing is a critical condition to analyze during the construction phase of underground gas storage facilities and a significant safety indicator during their operation. It is also an important aspect to study when increasing pressure and expanding capacity in gas storage facilities that have reached their designed capacity. This paper takes the Bai-6 gas storage facility in the Ban South Block as an example to analyze the fault distribution characteristics of the gas storage. Through a three-dimensional geological model, the stratigraphic properties at both ends of the faults are projected onto the fault model to establish a three-dimensional Shale Gouge Ratio (SGR) model, thereby quantitatively characterizing fault sealing. The results are compared with the SGR results calculated from data. The results show that fault sealing in the study area is mainly due to lithological juxtaposition sealing and fault rock sealing, particularly mud smear sealing. The F1, F4 and F5 faults, with larger displacements, have good sealing due to sand-mud juxtaposition on both sides of the faults. The F3 fault, with smaller displacement, exhibits sand-mud, sand-sand, and mud-mud juxtaposition, with an overall SGR of over 50%, indicating good sealing. The F8 fault, with smaller displacement, primarily shows mud-mud and sand-mud juxtaposition with a few sand-sand contact points, and an SGR above 20%, mostly above 40%, indicating good sealing. The F9 fault primarily shows mud-mud juxtaposition, with the sand-mud contact areas having an SGR of around 15%, indicating poor sealing.