不同井型下的天然气水合物降压开采产气产水规律  

Behaviors of gas and water production from hydrate induced by depressurization with different types of wells

作　　者：毛佩筱 吴能友 宁伏龙[2,4] 胡高伟 孙嘉鑫[4] 陈强 郭洋[2,3] 卜庆涛[2,3] 万义钊 MAO Peixiao;WU Nengyou;NING Fulong;HU Gaowei;SUN Jiaxin;CHEN Qiang;GUO Yang;BU Qingtao;WAN Yizhao(Chinese Academy of Geological Sciences,Beijing 100000,China;Laboratory for Marine Mineral Resources,Pilot National Laboratory for Marine Science and Technology-Qingdao,Qingdao,Shandong 266071,China;Key Laboratory of Gas Hydrate,Ministry of Natural Resources,Qingdao Institute of Marine Geology,Qingdao,Shandong 266071,China;Faculty of Engineering,China University of Geosciences-Wuhan,Wuhan,Hubei 430074,China)

机构地区：[1]中国地质科学院 [2]青岛海洋科学与技术试点国家实验室海洋矿产资源评价与探测技术功能实验室 [3]自然资源部天然气水合物重点实验室·青岛海洋地质研究所 [4]中国地质大学(武汉)工程学院

出　　处：《天然气工业》2020年第11期168-176,共9页Natural Gas Industry

基　　金：国家重点研发计划项目“水合物试采、环境监测及综合评价应用示范”(编号:2017YFC0307600);中国地质调查局二级项目“海域天然气水合物试采体系更新与新技术应用”(编号:DD20190231);青岛海洋科学与技术国家实验室开放基金项目“南海北部水合物多分支孔降压开采方法研究”(编号:QNLM2016ORP0207);山东省泰山学者特聘专家项目(编号:ts201712079)。

摘　　要：目前的研究成果表明,降压法及其改良方案可能是实现海域天然气水合物(以下简称水合物)高效开采的最佳途径,但现有降压条件下的产气能力距离水合物商业开发需求仍存在着不小的差距,因而提高水合物藏分解效率、提升储层气液运移产出能力,进而形成安全高效的水合物开采新方法,是水合物开发过程中急需解决的瓶颈问题。为此,利用自制的水合物复杂结构井模拟实验装置,分别开展了垂直井、水平二分支井(夹角90°)开采水合物的实验室模拟实验,据此分析不同开采条件下各井型的产气、产水规律。研究结果表明:①垂直井与分支井开采中,降压幅度是控制前期产气速率的主要因素,而后期环境温度对水合物分解量的影响则逐渐加强;②井型对水合物开采产能具有明显的控制作用——垂直井开采降压幅度越大,产气情况越好,但实验尺度下累计产水量则相差不大,水平二分支井(夹角90°)开采过程中,产气速率比射孔面积相同的垂直井更高,波动较小,但初始阶段产水明显;③降压—热激联合作用更有利于水合物的分解和稳定产气,在其联合作用下,水平二分支井(夹角90°)比垂直井更有利于水合物的长期稳产。Present research results show that depressurization and its improved scheme may be the most promising way to produce methane from marine gas hydrate-bearing reservoirs safely and effectively.However,the current depressurization-induced recovery rate is still far from the commercial-level gas flow.Thus,it is urgent to form a new,safe and efficient production method,which can significantly increase the gas hydrate dissociation efficiency and improve the fluid migration capacity during commercial-scale hydrate production.This paper mainly investigates the laws of gas and water production from methane hydrate-bearing sediments by different well layouts and production conditions.Experimental simulations of methane hydrate production by a single vertical well and a vertically distributed two-branch horizontal well(i.e.,the angle of two branches is 90°)have been carried out,using the customized complex structural well experimental simulation device.The results indicate that,(1)the gas production rate is mainly affected by the depressurization effect in the early stage when different production conditions and well layouts are employed.As production proceeds,the hydrate dissociation is gradually affected by the surrounding temperature;(2)the layout of the production well significantly influences the gas productivity.When the methane is produced by a vertical well,the greater the pressure drop is,the better the gas recovery.While the water production volume displays very little difference under different experimental production conditions.When the methane is extracted through the twobranch horizontal well,the gas production performance is better,and the production rate is more stable.However,the cumulative water production volume is large at the beginning;(3)Comparing with the depressurization method,the depressurization combined with thermal stimulation is more help for the hydrate dissociation and stable methane production.The two-branch horizontal well also shows the advantage of stable long-term gas production when me

关 键 词：甲烷水合物 垂直井 水平二分支井(夹角90°) 复杂结构井 降压开采 降压—热激联合开采 

分 类 号：TE37[石油与天然气工程—油气田开发工程]