渭河盆地西安凹陷地热田热储特征及开发方式

Thermal storage characteristics and development mode of geothermal field in Xi an sag of the Weihe basin

热源、热储层(砂体厚度、孔隙度、渗透率)、地温场等是影响地热资源评价的重要因素。本文以渭河盆地西安凹陷-西安市延长石油西化小区为例,在收集前人资料的基础上,应用地层测温、测井、岩芯分析等资料,分析了研究区地温场特征、热储层特征及地热资源量,运用多种参数对热储层有利区进行了综合评定。研究结果表明延长石油西化小区属地热异常区,地温梯度为3.5℃/100 m;研究区张家坡组、蓝田灞河组砂泥岩互层发育,砂厚分布在40~140 m之间,平均孔隙度分布在15.68%~30.3%之间,蓝田灞河组砂层厚度、地层热量、含水量和总热量均高于三门组和张家坡组地层,地热开发条件最好;综合考虑砂体厚度、地层含水量、地温梯度、地温、热储层物性因素,认为西安凹陷延长石油西化小区地热开发应选择蓝田灞河组为主要目的层段,最优的地热开发方式应采用采灌平衡法进行地热开采,综合考虑研究区更宜选择中深层地埋管井下换热方式进行地热资源开发。

There are several important factors that affect the evaluation of geothermal resources,such as heat source,thermal reservoir(sand thickness,porosity,permeability),geothermal field,etc.This paper considers the Yanchang Petroleum Xihua District of the Xi an sag as an example,and analyzes the geothermal field characteristics,thermal reservoir characteristics and geothermal resources by using formation temperature measurement,well logging,and core analysis data.We also use a variety of parameters to optimize the evaluation of the favorable areas of the thermal reservoir.The research results show that the geothermal gradient of the Yanchang Petroleum Xihua District is 3.56℃/100 m,which is a geothermal anomaly area.The Zhangjiapo and Lantian Bahe Formations in the Xihua District have developed interbeds of sand and mudstone,with sand thickness ranging from 40~140 m,and average porosity at 15.68%~30.3%.The sand thickness,formation heat,water content and total heat of the LantianBahe Formation is higher than those in the Sanmen and Zhangjiapo Formations,and the geothermal development conditions are the best.The Lantian Bahe Formation should be selected as the target stratum for geothermal development in the Xihua District of Xi an sag.The optimal geothermal development method should adopt the balance method of mining and irrigation for geothermal exploitation,and it is more appropriate to choose the underground heat transfer method of medium and deep buried pipes for geothermal resource development in the research area.