【作者】 林振洲；

【导师】 潘和平；

【作者基本信息】 中国地质大学 ， 地球探测与信息技术， 2019， 博士

【摘要】 木里地区是中国目前唯一发现天然气水合物的陆域冻土区,水合物以浸染状产于岩层的孔隙中,或以片状产于岩层的裂隙中,水合物储层岩性主要为泥岩、油页岩、粉砂岩、细砂岩等,赋存环境、产出形态和成藏机理等与海域和极地冻土区水合物存在显著差异。鉴于研究区勘查程度低,亟需通过分析水合物储层的测井响应特征和开展岩石物理实验,形成一套适合高山冻土区水合物储层的识别和评价方法,并研究异常特征的产生机理和主控因素。本文利用常规测井和超声成像测井资料,分岩性、赋存状态,讨论了水合物储层测井响应特征,结合岩心测试和岩电资料,建立了储层参数计算模型;构建了多种情况下的数字岩心,利用数值模拟方法研究了水合物产出形态、分布类型等因素对水合物储层电学特性的影响规律,提供了研究水合物储层电学特性与水合物分布及饱和度等影响因素之间关系的桥梁。主要研究过程和取得的成果如下:1.分析了含水合物储层和非储层的测井响应特征。分析表明木里地区的天然气水合物具有高电阻率、高声波速度、低密度的响应特征;电阻率对孔隙型水合物反映灵敏,电阻率和声波测井对裂隙型水合物反映灵敏,且研究区以裂隙型水合物储层为主。2.开展岩石物理实验,通过岩电、物性、声速测量获取地层参数,并对实验结果进行了整理和分析。3.利用X射线CT扫描法构建了水合物储层孔隙型数字岩心模型;然后基于分形理论,采用随机模拟方法构建了分形离散裂缝网络,并与孔隙性储层数字岩心叠合得到了裂缝性储层的三维裂缝网络数字岩心,为开展水合物储层数值模拟研究奠定了基础。4.利用最大球算法建立了与真实岩心具有相同拓扑结构和几何特征的孔隙网络模型,定性并定量地研究了水合物孔隙结构参数与水合物储层岩石物理特性之间的相关关系和孔隙结构等表征几何特征和拓扑结构的参数。5.采用有限元方法计算不同水合物分布、饱和度等情况下的数字岩心电阻率,分析了不同因素下的电性响应特征和主控因素,探讨了产生机理和对岩石宏观物理特性的影响规律;基于模拟结果,推断出研究区以接触型水合物分布类型为主。6.研究了水合物储层参数(泥质含量、孔隙度、饱和度等)计算模型。研究表明阿尔奇、修正阿尔奇、印度尼西亚等饱和度评价模型仍可适用于砂岩孔隙型水合物储层和泥岩、页岩裂隙型水合物储层含水饱和度的求取。建立了木里水合物储层最优化分析的目标函数,采用SR1、DFP、BFGS变尺度最优化方法反演计算储层参数。更多还原

【Abstract】 Muli area is the only land permafrost area where gas hydrates are found in China at present.Hydrates occur in the pores of rock formations as disseminated or in the fissures of rock formations as flakes.The lithology of hydrate reservoirs is mainly mudstone,oil shale,siltstone,fine sandstone,etc.The occurrence environment,occurrence form and reservoir formation mechanism differs significantly from those of hydrates in sea areas and polar permafrost areas.In view of the study area of low degree of exploration,a set of identification and evaluation for permafrost hydrate reservoir method is supposed to carry out through the analysis of response characteristics and rock physical experiment logging hydrate reservoir,and to study the formation mechanism and main controlling factors and research anomalies.In this paper,the logging response characteristics of hydrate reservoir were discussed by using conventional logging and ultrasonic imaging logging data in terms of lithology and occurrence state.Combining with core testing and electrical data,a reservoir parameter calculation model was established.Digital cores under various conditions were established,and the electrical characteristics of hydrate reservoir were studied by using numerical simulation method.It provided a link to study the relationship between electrical characteristics of hydrate reservoir and factors like hydrate distribution and saturation.The main research process and achievements are as follows:1.It analyzed the log response characteristics of hydrate and different lithologies.The analysis showed that the gas hydrate in Muli area was categorized as high resistivity,high acoustic velocity and low density;resistivity is sensitive to porous hydrate,resistivity and acoustic logging are sensitive to fractured hydrate,and the fractured hydrate reservoir is the main reservoir in the study area.2.It carried out the rock physics experiments and formation parameters were obtained by rock electricity,physical properties,and sound velocity measurement for further collation and analysis.3.It established the pore-type digital core model of hydrate reservoir by X-ray CT scanning method,and then established the fractal discrete fracture network was constructed by random simulation method based on fractal theory,and obtained the three-dimensional fracture network digital core of fractured reservoir by superimposing with the digital core of porous reservoir,which laid a foundation for numerical simulation of hydrate reservoir.4.A pore network model with the same topological structure and geometric characteristics as the digital core was established by using the maximum sphere algorithm.The correlation between the pore structure parameters of hydrate and the physical properties of hydrate reservoir rocks was studied qualitatively and quantitatively.The parameters of pore structure which characterize the geometric and topological characteristics were consistent with the calculation results of the digital core.5.By finite element method it calculated the digital core resistivity under different hydrate distribution and saturation conditions,the electrical response characteristics and main controlling factors under different factors,and it discussed the generation mechanism and the law of influence on the macro-physical characteristics of rocks.Based on the simulation results,it inferred that the hydrate distribution in the study area presented mainly as contact hydrate.6.It examined the calculation model of hydrate reservoir parameters(shale content,porosity,saturation,etc.).The study showed that the saturation evaluation models of Archie,Modified Archie and Indonesia can still be used to calculate the water saturation of sandstone porous hydrate reservoirs and mudstone and shale fractured hydrate reservoirs.The objective function for optimum analysis of Muli hydrate reservoir was established.The reservoir parameters were obtained with back calculation through SR1,DFP and BFGS variable scale optimization methods.更多还原