沁水盆地寿阳勘探区煤层气井排采水源层判识

煤层气井水源层判识,对于单井排采动态诊断、优选作业井层和制定科学的压裂方案均具有重要意义。针对寿阳勘探区煤层气井高产水问题,开展了区域水动力场和能量场、煤系砂岩和灰岩含水性、目标煤层围岩岩性连井对比、井筒与煤层围岩含水层连通关系以及典型煤层气井水源层剖析等方面的研究。研究表明,区域水动力场和煤层渗透率是煤层气井平均产水水平的决定因素,而煤层气井产水量的井间差异主要受控于单井波及范围内局部地质工程因素(断裂、压裂缝类型和高度及岩性组合),水力压裂缝是除断裂外煤层与围岩含水层沟通的一种方式。通过综合分析,本文取得的结论是,煤系砂岩是寿阳勘探区煤层气井的主要水源层,太原组灰岩对排采的影响有限。建议在煤层气开发井层优选和压裂方案设计时,重点考虑目标煤层与砂岩含水层的垂向组合关系。

Identification of aquifers influencing the drainage of coalbed methane wells in Shouyang exploration area，Qinshui Basin

Identification of aquifers influencing the drainage of coalbed methane wells are essential for diagnostic of well performance，selection of well sites/coalbeds for development operations and for fracturing design.Facing to the high water production problem in Shouyang CBM Exploration Area，In this article，regional hydrodynamic head and energy distribution characteristics，aquosity of snadstones and limestones in the coal measures，lithological association surrounding the target coals，hydraulic communication of coals with the surrounding aquifers and detailed analysis of water sources of typical wells were comprehensively studied.It is recognized that regional hydrodynamics and permeabilities of coalbed reservoirs control the average water production level，while the difference of water productions among wells are mainly controlled by local geological and engineering conditions (faults，hydraulic fractures types and height，and lithological assemblage surrounding the target coals) and hydraulic fractures are one mode，besides faults，of hydraulic communication between target coals and their surrounding aquifers.It is finally concluded that the sandstones in coal measures are the main water source layers and the limestones in Taiyuan formation has weak influence on the well drainage and water production.It is suggested that the selection of well sites/coalbeds for CBM development operations and fracturing design should be relied on the vertical combination of target coals and surrounding sandstone aquifers.