天然气水合物降压开采与出砂实验研究  

An experimental study of natural gas hydrates sand production using depressurization

作　　者：李占东 干毕成[3] 李中 张海翔 王殿举 刘淑芬[1,4] 李吉 LI Zhandong;GAN Bicheng;LI Zhong;ZHANG Haixiang;WANG Dianju;LIU Shufen;LI Ji(Heilongjiang Key Laboratory of Gas Hydrate Efficient Development,Daqing,Heilongjiang 163318,China;College of Offshore Oil and Gas Engineering,Northeast Petroleum University,Daqing,Heilongjiang163318,China;College of Petroleum Engineering Institute,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Sanya Offshore Oil&Gas Research Institute,Northeast Petroleum University,Sanya,Hainan 572025,China;CNOOC Research Institute,Beijing 100027,China)

机构地区：[1]黑龙江省天然气水合物高效开发重点实验室,黑龙江大庆163318 [2]东北石油大学海洋油气工程学院,黑龙江大庆163318 [3]东北石油大学石油工程学院,黑龙江大庆163318 [4]东北石油大学三亚海洋油气研究院,海南三亚572025 [5]中海油研究总院,北京100027

出　　处：《中国矿业大学学报》2020年第6期1128-1136,共9页Journal of China University of Mining & Technology

基　　金：国家重点研发项目(2018YFC0310200);黑龙江省教育厅研发项目(TSTAU-R2018018)。

摘　　要：出砂问题是制约水合物资源有效开发的关键因素,为了深入了解水合物降压开采与出砂规律,开展了4组不同渗透率条件CH4生成、分解以及出砂室内物理实验模拟,认为渗透率是影响地层出砂的关键因素.在天然气水合物降压生产过程中,产气量、产气率和出砂量与生产井的压力密切相关.水合物饱和度对产气率的影响是非线性的,但累积产气量随压力变化的曲线近似为线性.研究结果表明:1)水合物合成大概分为3个阶段:注入阶段、高诱发阶段和稳定生成阶段.不同渗透率地层回压总体差异不大,渗透率越高的地层压力下降的斜率越大,时间越早,最大压差为4.3 MPa.水合物生成的速率越快,但在稳定期间差异不明显;2)降压法进行水合物开采模拟,压力下降曲线呈梯度特征.降压开采大致分为4个阶段:快速分解初始阶段、水合物分解与稳定转变的竞相作用阶段、分解稳定阶段和地层出砂阶段.原始地层压力是影响水合物分解能力的直接因素,通过改变原始地层压力可以提高CH4水合物开采速度,内径为200μm的样品最大的产气速度可以达到238 mL/min;3)当地层处于出砂临界状态,不同渗透率出砂速度不同,渗透率越高,渗透率最大的样品较渗透率最低的样品出砂时间提前50 h.分解产气误差控制在3.42%以内,分解产水控制在2.14%以内,可以说明模型在预测地层出砂分解产气和产水具有较好的预测作用.Sand production is a key factor restricting the effective development of hydrate resources. In order to understand the law of hydrate decompression mining and sand production, four sets of indoor physical experiment simulations of CH4 generation, decomposition, and sand production under different permeability conditions were carried out. It is considered that the permeability is a key factor affecting the formation of sand. In the process of gas hydrate decompression production, gas production, gas production rate and sand production are closely related to the pressure of the production well. The effect of hydrate saturation on gas production rate is nonlinear, but the curve of cumulative gas production rate with pressure is approximately linear. The results demonstrated that:(1) The synthesis of natural gas hydrates(NGH) can be divided into three stages: the gas injection stage, the high induction stage, and the stable synthesis stage. At different permeabilities, formations have minimal effects in back pressure. The formation with higher permeability yields to a greater descending slope with a faster synthesis of the hydrate(The maximum pressure difference is 4.3 MPa). However, the difference is not evident during the stable synthesis stage.(2) When using the depressurization method to stimulate the hydrate production, the curve of the formation pressure declines in a gradient manner. The NGH production by depressurization is roughly divided into four stages: the initial stage of the rapid decomposition, the competition stage of the hydrate decomposition and stable transformation, the stable decomposition stage and the sand production stage. The original formation pressure is a direct factor that affects the ability of hydrate decomposition. Changing the original formation pressure can increase the production rate of CH4 hydrate. The maximum gas production rate of sample with an inner diameter of 200 μm can reach 238 mL/min.(3) When the formation is in the critical state of sand production, different permeabil

关 键 词：天然气水合物 降压开采方法 地层出砂 采气速度 采气量 

分 类 号：TE312[石油与天然气工程—油气田开发工程]