印尼N气田砂体预测研究

SAND-BODY PREDICTION OF N GAS FIELD IN INDONESIA

印尼N气田下第三系 LTAF地层是河流—三角洲—浅海沉积体系,分支流河道微相是区内最主要的储集相带。文章采用测井—地震结合进行高分辨率等时对比、岩心观察,建立了沉积层序和微相构成及利用地震反演进行高分辨率井间储层定量预测相结合的描述方法,对分支河道砂体的分布有了重要认识。研究表明,区内主要目的层可以划分为2个超中期旋回、4个中期旋回、8 个短期旋回等多级次基准面旋回,分流河道及其伴生微相在成因上制约了储层的空间分布。高分辨率的密度反演结果定量地预测了分流河道砂体的空间展布,主要呈长条状或宽带状,在不同基准面时期展布规律不同,总体显示出沉积的复杂性。三角洲平原上可容纳空间与沉积物供给量比值(A/S)是控制分流河道砂体叠加、迁移的关键;高分辨率层序地层学、开发地震与油藏描述相结合的方法进行河道砂体的定量预测,是表征河道砂体的行之有效的方法。该成果已运用到海外油气田的生产实际中,对油气开发有着重要的指导意义。

The LTAF of Lower Tertiary in N gas field in Indonesia belongs in a fluviodelta-neritic deposit system, and the distributary channel microfacies is the most important reservoir facies zone in the field. An important cognition upon the distribution of distributary channel sand bodies was obtained through establishing the sedimentary sequence and microfacies constitution by applying the high-resolution isochronous stratigraphic correlation of combining log data with seismic data and the core observation, and through carrying out high-resolution interwell reservoir quantitative prediction by applying seismic inversion. The research results indicated that the main target zones in the field might be divided into many multistage datum cycles, such as two super medium-term cycles, four medium-term cycles and eight short-term cycles, etc.; the spacial distribution of reservoir was controlled by distributary channel and its associated microfacies genetically; the spacial distribution of distributary channel sand bodies being in strip-like or wide belt-like was predicted by the high-resolution density inversion result, the distributional laws being different at different datum periods and a sedimentary complicacy being shown up on the whole; on delta plain, the acceptable space-sedimentary supply ratio (A/S) was the key factor of controlling the superposition and migration of distributary channel sand bodies; and it was an effective way to carry out the quantitative prediction of the sand bodies by use of the method of combining the high resolution sequence stratigraphy and development seismics with the reservoir description. The research results are of great importance and have been used for the exploration and development of oversea oil and gas fields.