南海水合物及伴生游离气储层封堵改造与水平井降压合采模拟研究  

Numerical simulation on co-extraction of hydrate and free gas in the South China Sea using a combination of formation sealing and horizontal well techniques

作　　者：秦帆帆 孙嘉鑫[1] 游志刚 曹鑫鑫 张凌[1] 宁伏龙[1] QIN Fanfan;SUN Jiaxin;YOU Zhigang;CAO Xinxin;ZHANG Ling;NING Fulong(National Center for International Research on Deep Earth Drilling and Resource Development,Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China)

机构地区：[1]中国地质大学(武汉)工程学院,地球深部钻探与深地资源开发国际联合研究中心,湖北武汉430074

出　　处：《地质学报》2024年第9期2806-2821,共16页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号42372361,42225207);广东省基础与应用基础研究重大项目(编号2020B0301030003)联合资助的成果。

摘　　要：中国南海赋存有丰富的水合物资源,且储层周围或下部往往伴生有大量的游离气。迄今为止,南海已发现的大多数水合物储层泥质含量高,渗透率低,降压开采压降难以有效传递,产能束缚严重,例如神狐海域水合物储层两次试采产能均未达到商业开发标准。因此,将水合物气和伴生游离气联合开采逐渐提上日程。在扩大水合物和伴生气储层泄流面积的同时,进一步寻求高效的增产手段是突破开采产能低的关键。储层封堵改造作为一种提高压降传递的有效手段,能够促进水合物分解和伴生气采收,具有良好的应用前景。故而,本文基于中国南海第一次水合物试采站位地质资料,构建了三维非均质开采模型,重点评估了水平井结合储层封堵改造条件下的两气合采产能,并进一步系统研究了封堵层半径、厚度、渗透率比值以及水平井长度对两气合采产能的影响,分析了合采过程中水合物分解气对总产能的最大贡献率(w)。模拟结果表明,水平井辅以储层封堵能有效提高产能,其中水平井长度、封堵层半径和渗透率比值对合采产能影响依次减弱,水平井长度与封堵层直径两个因素之间存在交互影响。此外,伴生气是两气合采过程中的主要气源,储层封堵后井位布设于游离气层较布设于三相层可进一步提高产能。上述研究认识对于提产增效,推动水合物产业化具有重要的工程指导意义。The South China Sea hosts abundant gas hydrate resources,often accompanied by significant amounts of free gas deposits distributed around or beneath the hydrate reservoir.However,most discovered hydrate reservoirs in this region have high mud content and low permeability,posing a challenge to effective pressure drop transfer during depressurization and leading to substantial productivity constraints.For example,the production capacity in the Shenhu area does not meet commercial development standards.As a result,there is a growing consideration towards combined production of hydrate gas and associated free gas.While expanding the drainage area of both hydrate and free gas reservoirs is crucial,the key to unlocking their full production potential lies in exploring efficient enhancement methods.Formation sealing,an effective technique for improving pressure drop transfer,can facilitate hydrate dissociation and enhance free gas recovery,showing promising prospects for application.This paper leverages geological data from the first gas hydrate trial production test in the South China Sea to establish a three-dimensional heterogeneous production model.The study focuses on evaluating the co-extraction potential of hydrate and free gas through horizontal wells and formation sealing.It systematically examines the effects of sealed layer radius and thickness,permeability ratio,and horizontal well length.Additionally,the maximum percentage of gas contribution from hydrate dissociation(w)during coextraction is calculated.Simulation results demonstrate that incorporating formation sealing with horizontal wells significantly enhances production potential.The relative impact of the investigated parameters on production capacity follows a descending order:horizontal well length,sealed layer radius,and permeability ratio.An interactive effect is observed between horizontal well length and sealed layer diameter.Free gas serves as the primary source of gas trapped in the entire co-production process,and deploying horizontal well in

关 键 词：天然气水合物 两气合采 储层改造 数值模拟 

分 类 号：P744.4[天文地球—海洋科学]