【作者】 刘亚平；

【导师】 陈月明；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2009， 博士

【摘要】 天然气水合物(Natural Gas Hydrates,NGH)是一种潜力巨大的优质、清洁替代能源,其商业性开采已经被逐渐提上日程。NGH藏开发方案基础研究是NGH藏商业开采的基础和前提,是一项前瞻性(超前)工作。其中涉及NGH藏品质评价、不同品质NGH藏开发动态分析、不同品质NGH藏开发方案经济评价前沿课题。目前,尚未有相关课题研究。因此,NGH藏开发方案基础研究具有重要的理论价值和现实意义。鉴于NGH藏目前研究现状,降压法是NGH藏开采的基本方法,本研究从理论分析、室内实验和数值模拟三个方面出发,对NGH藏降压开发方案进行了以下几个方面的研究:建立了NGH藏品质评价模型。该评价模型综合分析了NGH藏含气系统,采用数值模拟方法计算了NGH藏参数的敏感性,确定NGH藏开发敏感性较大的12个参数为NGH藏品质评价的因素集,同时参考油田评价分数的确定方法,建立了NGH藏品质评价的评语集,然后对每个因素进行评分区间划分,即对应评语集对每个因素进行区间划分。对因素集进行层次划分,利用层次分析法确定权重,最终建立两级NGH藏储层品质评价模型,并利用该模型研究分析了四种典型NGH藏的品质等级。以相似理论为指导设计了一套拟三维NGH藏开发比例物理模拟平台,进行了不同品质NGH藏降压开发室内实验研究。从开采NGH藏的数学模型出发,应用检验分析方法和量纲分析方法推导了NGH藏开发的39个相似准则数,为物理模型相似提供了设计原则。通过对NGH藏降压开发实验数据进行模型和原型之间的相似转化得到不同品质NGH藏的降压开发动态规律。实验结果表明NGH藏降压开发过程分为自由气产气、NGH分解产气、NGH分解气和自由气共同产气三个阶段,三个阶段产气速度逐级降低;NGH分解产气量占总产气量的比例随着NGH藏品质提高而逐级增加;累积产气量和开采时间随着NGH藏品质的降低而逐级减少。建立NGH藏开发数学模型并编制相应的数值模拟计算程序。利用所编制的NGH藏开采数值模拟程序模拟了不同品质NGH藏的降压开发过程,分析了不同品质NGH藏降压开发特征,讨论了井底流压对不同品质NGH藏降压开发动态参数的影响。数值模拟研究结果表明产水速率、累计产水量与井底流压的敏感性较强,随井底流压的降低而迅速增加;产气速率、累计产气量随井底流压的降低而增加,但是对井底流压的敏感性相对较弱。提供了一套较为完整的NGH藏开发经济评价方法。在数值模拟研究的基础上,利用内部收益率法计算了NGH藏极限经济产量。采用净差额现金流量分析方法对不同品质NGH藏进行经济评价。经济评价结果表明一、二、三级NGH藏降压开发具备商业开采价值,四级NGH藏降压开发在经济上是不可行的。更多还原

【Abstract】 As an alternative energy resource with huge potential, natural gas hydrates (NGH), commercial exploitation of NGH has been paid much attention to in recent years. The fundamental studies on NGH reservoir development is the premise and foundation to commercial exploration of NGH reservoir and is a very advancing step in NGH development, involving in many challenging issues such as NGH quality evaluation, production performance analysis for NGH reservoir of different quality as well as project economic evaluation for NGH reservoir of different quality. At present, there is no relevant research. Therefore, the study of NGH reservoir development is of great theoretical and practical value.Focusing on the challenges mentioned above, the NGH reservoir depressurization development as an important way for NGH exploration is studied through theoretical research, laboratory experiment and numerical simulation in this paper. The following research is conducted:The quality evaluation model of NGH reservoir is built, which analyzed comprehensively the gas-bearing NGH reservoir. Based on numerical simulation, the sensitivities of all parameters are analyzed, and 12 parameters with great impact are determined as the factor set of NGH reservoir quality. With reference to oil field evaluation criteria, the comment sets of NGH reservoir quality evaluation are ascertained, and interval division of each factor is defined for corresponding comment sets. With the multi-layered division of main controlling factors set that influence development effect, the weights for the factors are determined with the the analytic hierarchy process analysis. The two-stage quality evaluation model of NGH reservoir is finally established, and quality grades of 4 typical NGH reservoirs are obtained using this model.Guided by similarity theory, a set of quasi-3-D scale physical simulation model for NGH is designed, and the NGH reservoir development experiments of different qualities were conducted. By means of dimensional analysis and check analysis, 39 similarity criteria of NGH reservoir development are derived based on the NGH reservoir mathematical model, therefore providing design principle for the model similarity. Based on the similarity transformed data between the model and the prime type, the dynamic laws of depressurization development for different quality NGH reservoir are obtained. The experiments results showed that the NGH reservoir depressurization development could be divided into three stages: the free NGH gas production, dissolved NGH gas production and free & dissolved NGH gas production, the gas production decreased step by step. The dissolved NGH gas production occupied a higher proportion of the total gas production as the quality of NGH reservoir increased. The accumulative gas production and the production time decreased as the quality of NGH reservoir decreased.The mathematical model for NGH reservoir development is built, and the corresponding simulation calculation program is compiled. By using the program, depressurization development characteristics of different quality NGH were analyzed. The effects of bottom hole production pressure on NGH reservoir of different quality depressurization development parameters were analyzed. The numerical simulation results showed that the water production and cumulative water production have stronger sensitivity relationship with flowing bottom hole pressure and increase as the flowing bottom hole pressure decreases. Off-take rate and cumulative velocity appear less sensitivity with flowing bottom hole pressure.A complete set of economic evaluation methods for NGH reservoir development is proposed. By the method of internal rate of return, production limit of NGH is calculated based on numerical simulation. The economic evaluation for NGH reservoir of different quality is carried out. Economic evaluation results showed that the depressurization development of the first, second and third class NGH reservoir have commercial exploitation value. The depressurization development of the forth class NGH reservoir is not economically feasible.更多还原