涩北一号气田勘探历程及储量增长因素分析

Exploration history of Sebei No.1 gas field and an analysis of factors affecting reserve increase

涩北一号气田位于柴达木盆地东部，勘探历史长达２０余年。第一阶段（１９６４～１９７７年）多数井打在构造外围，含气高部位实际无井控制，加之使用盐水钻井液而导致电阻率测井曲线失真，遗漏大量气层，估算Ⅱ类探明天然气储量为３７．０４×１０８ｍ３；第二阶段（１９９０～１９９１年）补钻５口评价井，各井测井资料质量都比较好（以高电阻率和高声波时差为依据解释气层），取了总长３１８．６１ｍ的岩心，获得大量分析化验资料，在此基础上重新计算气田储量，累计Ⅱ类探明天然气储量为１６２．０１×１０８ｍ３；第三阶段（１９９６～１９９７年），已有４ｋｍ×６ｋｍ地震测网密度的地震资料，在地震处理成果指导下钻涩２７井，根据涩２７井和Ｓ４３井选层（低声波时差层）试气结果，建立了新的气层解释标准，再次计算气田储量，累计Ⅱ类探明天然气储量达到４９２．２２×１０８ｍ３。储量大幅度增长的关键，在第二阶段是改善测井环境从而提高了测井资料的质量，在第三阶段是找到了符合气田地质规律的测井解释标准。涩北一号气田的勘探史是对老资料不断深入认识的历史，为老油气田的地质研究提供了有益的经验。

Sebei No.1 gas field is located in the east part of Qaidam basin with an exploration history of more than 20 years. In the first stage (19641979), most wells were drilled in the outer part of the structure and no wells drilled in the high part of gas area actually; in addition, salt water was used as drilling fluid, so that resistivity logging records were distorted and large amount of gas sands were missed; thus controlled gas reserves was estimated to be 37.04108m3. In the second stage (19901991), 5 appraisal wells were completed, all well logging records were obtained with a good quality, (gas sands were interpreted with a characteristic of high resistivity and high acoustic time transit as a basis), and a total length of 318.61m Author cores were obtained; so that a large amount of laboratory analysis were made, and gas reserves were reestimated on such a basis. Total controlled gas reserves is estimated to be 162.01108m3. In the third stage (19961997) a network of 4km6km seismic record was obtained, under the guidance of seismic interpretation and data from the new drilled Well Se27 new standard for gas pay interpretation was establishedbased upon selective gas production test data; and the gas reserves were estimated again to be 492.22108m3. Key to the reserve increase is the improvement of logging environment to modify the quality of logging records in the second stage, and to establish the standard for logging interpretation according to the characteristics of the gas field geology. The exploratory history of Sebei No.1 gas is a history of successive recognition of all old field data, and this will give a beneficial experience for studying a old oil/gas field.