南海水合物储层水平井钻进时泥浆侵入特性模拟研究  

Simulation study of mud intrusion characteristics during drilling of horizontal wells in hydrate reservoirs in the South China

作　　者：胡锦秋 吕万军 张卓 张准 Sea HU Jinqiu;LÜWanjun;ZHANG Zhuo;ZHANG Zhun(College of Marine Science and Technology,China University of Geosciences,Wuhan,Hubei 430074,China)

机构地区：[1]中国地质大学(武汉)海洋学院,湖北武汉430074

出　　处：《地质学报》2024年第9期2781-2794,共14页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41876069)资助的成果。

摘　　要：天然气水合物是一种无污染的新型非常规能源,加快天然气水合物的开发利用,对环境保护和能源发展具有重要意义。钻井是水合物勘探开发的重要一环,直接影响水合物地层勘探的准确性和开采的稳定性。因此,本文利用TOUGH+HYDRATE构建水合物地层模型,预测了钻采条件下水合物储层动态响应特征、研究了泥浆参数特征(密度、温度、盐度)和含水合物地层物性(孔隙度、绝对渗透率、水合物饱和度)对泥浆侵入的影响规律,结果表明:泥浆在含水合物地层中的侵入是一个动态的传热传质过程,并伴随有相变行为。在采用水平井钻进水合物储层过程中,压力传递先于温度传递,且泥浆向下的侵入程度最大。压力和温度传递在侵入1天时基本稳定,但水合物会继续分解。一方面,泥浆密度、温度和盐度的增大均会加剧泥浆的侵入程度,因此需根据实际地层条件,选取合适的泥浆密度和较低的温度及盐度,并添加动力学抑制剂或者防聚剂。另一方面,地层孔隙度和水合物饱和度的增大将导致水合物分解程度增大,而分解范围减小。此外,地层绝对渗透率显著影响泥浆的侵入,地层绝对渗透率取2.9×10^(-4)μm^(2)、2.9×10^(-3)μm^(2)和2.9×10^(-2)μm^(2)时,泥浆侵入深度分别为0.2 m、0.5 m和2 m。Natural gas hydrate is a new type of non-polluting unconventional energy source.Accelerating its development and utilization is of great significance for both environmental protection and energy security.Drilling plays a vital role in hydrate exploration and development,directly impacting the accuracy of stratigraphic exploration and the stability of production operations.This study employs the TOUGH+HYDRATE numerical simulator to construct a hydrate stratigraphic model.We investigate the dynamic response of a hydrate reservoir subjected to drilling conditions,focusing specifically on the influence of mud parameters(density,temperature,salinity)and hydrate-bearing formation properties(porosity,absolute permeability,hydrate saturation)on mud intrusion.Our findings reveal that mud intrusion in hydrate-bearing formations is a complex,dynamic process characterized by coupled heat and mass transfer,accompanied by phase change behavior.During horizontal well drilling,pressure transfer precedes temperature transfer,resulting in the most significant downward mud intrusion.While pressure and temperature gradients stabilize within approximately one day of intrusion,hydrate decomposition persists.Increasing mud density,temperature,and salinity demonstrably exacerbates mud intrusion.Therefore,selecting appropriate mud density and using lower temperature and salinity mud,along with kinetic inhibitors or anti-polymerization agents,is essential.Conversely,elevated formation porosity and hydrate saturation lead to increased hydrate decomposition and a reduced decomposition range.In addition,absolute permeability exerts a significant influence on mud intrusion depth.Our simulations demonstrate that for absolute permeabilities of 2.9×10^(-4)μm^(2),2.9×10^(-3)μm^(2),and 2.9×10^(-2)μm^(2),the corresponding mud intrusion depths are 0.2 m,0.5 m,and 2 m,respectively.

关 键 词：天然气水合物 数值模拟 泥浆侵入 储层响应 

分 类 号：P744.4[天文地球—海洋科学]