石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (5): 1630-1645.doi: 10.11743/ogg20250515

• 油气地质 • 上一篇    

断层-砂体配置演化模式对远源型致密砂岩气差异富集的影响——以川中地区侏罗系沙溪庙组为例

刘明洁1(), 刘恒宇2, 肖尧3, 宋林珂3, 曹脊翔3, 李唐律3, 王锦西3, 梁晨1   

  1. 1.西南石油大学 地球科学与技术学院，四川 成都 610500
    2.中国石油 西南油气田分公司 勘探事业部，四川 成都 610041
    3.中国石油 西南油气田分公司 致密油气勘探开发项目部，四川 成都 610056
  • 收稿日期:2025-03-28 修回日期:2025-09-08 出版日期:2025-10-30 发布日期:2025-10-29
  • 第一作者简介:刘明洁（1985—），男，博士，副教授，储层地质学、油气成藏机理与富集规律。E‑mail： mjliu@swpu.edu.cn。
  • 基金项目:
    国家自然科学基金项目(41872154);中国石油西南油气田分公司科技项目（20210303-24,XNS致密JS2021-152）

Effects of the fault-sandbody configuration evolution model on differential enrichment of far-source tight sand gas： A case study of the Jurassic Shaximiao Formation， central Sichuan Basin

Mingjie LIU1(), Hengyu LIU2, Yao XIAO3, Linke SONG3, Jixiang CAO3, Tanglyu LI3, Jinxi WANG3, Chen LIANG1   

  1. 1.School of Geoscience and Technology，Southwest Petroleum University，Chengdu，Sichuan 610500，China
    2.Exploration Division，Southwest Oil & Gasfield Company，PetroChina，Chengdu，Sichuan 610041，China
    3.Tight Oil and Gas Exploration and Development Project Department，Southwest Oil & Gasfield Company，PetroChina，Chengdu，Sichuan 610056，China
  • Received:2025-03-28 Revised:2025-09-08 Online:2025-10-30 Published:2025-10-29

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摘要：

为明确川中地区侏罗系沙溪庙组远源型致密砂岩气差异富集规律，基于气源断层解释、砂体刻画与成藏期古构造恢复，分析了沙溪庙组成藏期与现今断层-砂体配置关系，明确了成藏期至今断层-砂体配置演化模式及分布规律，进而结合现今产气井分布特征探讨了该演化模式对天然气差异富集的影响。研究结果表明：沙溪庙组断层-砂体配置关系存在断层与近水平砂体对接（①类）、断层与倾向一致的缓倾角砂体对接（②类）以及断层与倾向相反的缓倾角砂体对接（③类）3类；成藏期至今断层-砂体配置演化模式分为继承型（Ⅰ型，其中成藏期与现今均呈③类，即Ⅰ1型；均呈①类，即Ⅰ2型）、调整型（Ⅱ型，成藏期呈①类，演化至现今呈③类）和反转型（Ⅲ型，即成藏期呈③类、演化至现今呈②类）。这3种断层-砂体配置演化模式对天然气富集可产生不同影响：Ⅰ1继承型演化模式导致天然气主要在断层上盘富集并继承保存至今，气井多表现为高产和中产；断层下盘仅聚集少量天然气并继承保存至今，气井多表现为低产。Ⅰ2继承型演化模式导致天然气主要在断层两盘聚集并继承保存至今，断层两盘气井多表现为中产和低产。调整型演化模式导致天然气在断层两盘聚集并调整改造至今，其中上盘经调整可进一步聚集或富集天然气，气井可表现为高产、中产或低产；断层下盘经调整可使天然气逸散，气井多表现为低产和特低产。反转型演化模式导致天然气在上盘富集并经反转散失至今，而在下盘少量聚集并经反转调整再次聚集至今，断层两盘气井多表现为低产和特低产。川中地区北部金秋区块Ⅰ1继承型演化模式产生的上盘继承保存富集型天然气、调整型演化模式产生的上盘调整改造富集型天然气，可作为下一阶段沙溪庙组远源型致密砂岩气勘探的重点。

关键词: 差异富集, 断层-砂体配置, 远源型, 致密砂岩气, 沙溪庙组, 川中地区

Abstract:

This study aims to determine the differential enrichment patterns of far-source tight sand gas in the Jurassic Shaximiao Formation， central Sichuan Basin. By conducting seismic interpretation of source rock-rooted faults， characterizing sand bodies， and reconstructing paleostructures during hydrocarbon accumulation， we analyze the fault-sandbody configuration modes in the Shaximiao Formation both during the hydrocarbon accumulation period and in the present day. Furthermore， the evolutionary model and spatial distribution of the configuration from the hydrocarbon accumulation period to the present are identified. Based on these， as well as the distribution characteristics of current gas producers， we explore the influence of the evolutionary model on differential natural gas enrichment. The results reveal the presence of three distinct modes of fault-sandbody configuration in the Shaximiao Formation， that is， juxtaposition of fault against near-horizontal sandbodies （mode 1）； juxtaposition of fault against gently dipping sandbodies with consistent dip directions （mode 2）； and juxtaposition of fault against gently dipping sandbodies with opposite dip directions （mode 3）. From the hydrocarbon accumulation period to the present， the fault-sandbody configuration modes have experienced three types of evolutionary patterns： inherited （type Ⅰ）， adjusted （type Ⅱ）， and reversed （type Ⅲ）. Specifically， type Ⅰ can be further divided into type Ⅰ1 （mode 3 persisting both during the hydrocarbon accumulation period and in the present day） and type Ⅰ2 （mode 1 persisting during both periods）. Type Ⅱ is characterized by a transition from mode 1 during the hydrocarbon accumulation period to mode 3 at present， while type Ⅲ represents a shift from mode 3 during the hydrocarbon accumulation period to mode 2 in the present day. These three types of evolutionary patterns exert different influences on natural gas enrichment. Specifically， the type Ⅰ1 inherited evolutionary pattern enables natural gas to accumulate primarily in the hanging wall blocks of faults and remain preserved to the present day. Consequently， most gas producers located in these blocks show high or moderate productivity. In this evolutionary pattern， only a small amount of natural gas accumulates in the footwall blocks of faults and remains preserved to date， leading to low productivity in most wells in these blocks. The type Ⅰ2 inherited evolutionary pattern allows natural gas to accumulate and remain preserved to date primarily in both the hanging wall and footwall blocks， with most gas producers in these blocks showing moderate or low productivity. The type Ⅱ adjusted evolutionary pattern facilitates the accumulation， adjustment， and modification of natural gas in both the hanging wall and footwall blocks. Consequently， natural gas may further accumulate or get enriched in the hanging wall blocks， where gas producers show high， moderate， or low productivity. In contrast， natural gas may escape from the footwall blocks after adjustment， resulting in low or ultra-low productivity in most gas producers in the footwall blocks. The type Ⅲ reversed evolutionary pattern leads to natural gas enrichment in the hanging wall blocks but dissipation to date due to reversal， with only a small amount of natural gas accumulating in the footwall blocks and reaccumulating there to date after reversal. In this pattern， most gas producers in the hanging wall and footwall blocks show low or ultra-low productivity. The Jinqiu block， located in the northern part of the central Sichuan Basin， contains two types of natural gas accumulation： （1） natural gas accumulation in the hanging wall blocks， characterized by inherited preservation and enrichment， under the type Ⅰ1 inherited evolutionary pattern； and （2） natural gas accumulation in the hanging wall blocks， featuring adjustment， modification， and enrichment， under the type Ⅱ adjusted evolutionary pattern. Therefore， this block be prioritized as a key target area for future exploration of far-source tight sand gas in the Shaximiao Formation.

Key words: differential enrichment, fault-sandbody configuration, far-source, tight sand gas, Shaximiao Formation, central Sichuan Basin

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