木里地区天然气水合物测井响应特征

摘要

The presence of gas hydrate and the lithology of reservoirs in Muli area are significantly different from those in the sea area or polar permafrost zone.For analyzing the logging response characteristics of the hydrate reservoir in the study area,the hydrate storage layer identification method is of great significance for hydrate exploration in this area.In this paper,the characteristics of well logging and the causes of hydrate logging were discussed by using conventional logging and ultrasonic imaging logging data,and the characteristics of reservoir logging parameters were calculated.The hydrate recognition was carried out in the study area.Some conclusions have been reached:(1) The apparent resistivity and natural gamma ray are sensitive to the pore hydrate,and the apparent resistivity and the longitudinal wave velocity are sensitive to the fissure hydrate.(2) The thick hydrate of the geological catalog could be identified,with the identification of some suspected hydrate reservoirs,but a small amount of drilling thin layer of hydrate failed to identify the analysis of the reasons for the low hydrate content,resulting in non-obvious logging response characteristics;(3)10 wells in the study identified hydrate and suspected hydrate anomalies,in which the cumulative thickness of the pore-type reservoir was 89m,and the cumulative thickness of the fractured reservoir was 151.6m.Therefore,the fractured hydrate reservoir is the main research area.In summary,the geophysical logging method has a good response to the hydrate reservoir,and can be effectively applied to the reservoir identification of all the boreholes in the study area.%木里地区天然气水合物附存状态和储层岩性与海域或极地冻土区的水合物存在明显差异,为分析研究区水合物储层的测井响应特征,形成基于该特征的水合物储层识别方法,对本地区水合物勘探具有重要意义.文中利用常规测井和超声成像测井资料,分岩性、分附存状态,讨论了多种情况下水合物测井响应特征及产生的原因,统计出储层测井参数值的范围,并对研究区钻孔进行了水合物识别.研究结果表明:①视电阻率和自然伽马对孔隙型水合物反映灵敏,视电阻率和纵波速度对裂隙型水合物反映灵敏;②地质编录的厚层水合物均能识别,且识别出一些疑似水合物储层,但少量钻遇的薄层水合物未能识别,分析原因为水合物含量偏低,导致测井响应特征不明显;③研究区10口井识别出水合物和疑似水合物异常,其中孔隙型储层累计厚度89 m,裂隙型储层累计厚度151.6m,故研究区以裂隙型水合物储层为主.综上所述,地球物理测井方法对水合物储层有很好的响应,可有效运用于研究区所有钻孔的水合物储层识别工作.