基于COMSOL的储层参数与层理缝对地热产能影响规律研究

Research on the effect of geothermal reservoir parameters and bedding fractures on geothermal deliverability based on COMSOL

地热能具有绿色、稳定、资源丰富、可再生等优点,可用来发电及工业、住宅供热.应用COMSOL多物理场耦合数值软件通过建立温度-渗流耦合模型,考虑工作介质物性参数随温度的变化,针对热储层参数及层理缝对地热能开发效果的影响展开研究.结果表明:热储压力在开发初期恢复缓慢的原因与开发初期注采井附近温度差异有关;裸眼段长度为40 m时可控热储层厚度为150 m;一注一采井距为300 m时注采系统可控热储层半径为400 m;基质渗透率大于80×10-15m2将影响热储开发寿命;基质孔隙度、基质热传导系数对热储开发影响较小,基质比热容越大越有利于热储开发;层理缝条数、导流能力对热储开发有较大影响,层理缝条数增加,产出液质量流量增加,热突破快,持续开发寿命缩短,层理缝的不合理利用将遮挡注入流体的波及范围.研究成果可为高温地热选层提供有力技术支持.

Geothermal energy can be used for power generation and industrial,residential heating,and it has many advantages,such as environment-friendly, stable, abundant resources, renewability.Through the establishment of thermal coupled seepage model,considering the variation of physical property parameters with temperature,we studied the effect of reservoir parameters and bedding fractures on geothermal deliverability. The results indicate that the slow pressure recovery in the early stage of the development of geothermal storage is related to the temperature difference between the injection and production wells in the early stage of development; When the length of the naked hole is 40 m,the thickness of the controllable geothermal reservoir is 150 m; When the injection production system adopted one injection well and one production well,and the well spacing is 300 m,the controlled geothermal reservoir radius of the injection production system is400 m; Matrix permeability exceeds a certain value will affect the development of geothermal exploitation longevity; Matrix porosity and matrix geothermal conductivity have little influence on the development,heat capacity is more conducive to the development;The number of bedding fractures and its flow conductivity has great effect on reservoir development. With increase of the number of the bedding fractures,the production mass flow increase,at the same time, faster the hot breakthrough velocity, eventually lead to reduction of the duration of development. And the unreasonable use of bedding fractures will block the swept area of injected fluid. The research results can provide strong technical support for the hightemperature geothermal reservoir selection.