苏里格气田国际合作区河流相储层井位部署关键技术

苏里格气田国际合作区位于该气田中南部,其开发层系属于二叠系复杂河流相岩性气藏,掌握河流相储层的类型、分布、规模和集中程度,是合理高效部署开发井位的前提和基础。通过实践探索与技术攻关,在该区形成了以三维地震泊松比岩性识别、棋盘式井网主河道带预测、河道微相精细解剖、动—静结合高产井筛选及东—西向水平井钻探为核心的井位部署关键技术。应用效果表明:(1)泊松比地震反演可有效识别厚砂岩(砂岩泊松比介于0.19~0.25,泥岩泊松比介于0.27~0.30),把握大河道带的分布;(2)通过提取棋盘式井网净砂岩(自然伽马小于60 API,有效孔隙度大于6%,含气饱和度大于60%)厚度能快速识别河流中心部位;(3)明确该区发育2类叠置河道带、5种主要沉积相和10种河道微相;(4)单井动—静态数据分析表明,具有低自然伽马值(小于40 API)、高有效孔隙度(超过10%)及较高深电阻率响应(大于90Ω·m)是上古生界二叠系下石盒子组盒8段高产井(单井最高可采储量超过1×108 m~3)的典型配置;(5)在辫状主河道带中心区域部署东—西向水平井有利于横向沟通多期河道。结论认为,该套井位部署关键技术加深了对该区河流相储层地质规律的认识,有效支撑了该合作区的开发建设。

Key technologies for well location deployment in fluvial reservoirs in the southern Sulige Block,Ordos Basin,a CNPC-Total joint project

The CNPC-Total joint natural gas project is located in the south central Sulige Gasfield, and its development target is lithologic gas reservoir of complex fluvial facies. The prerequisite and fundament for rational and efficient well deployment and development is to figure out the types, distribution, scale and concentration degrees of those fluvial reservoirs. Based on practical exploration and technical research, a series of key technologies for well location deployment in this block have been developed, including lithology identification based on the 3D seismic Poisson ratio, prediction of main channel belts in a chessboard well pattern, channel micro-facies dissection, dynamic-static selection of high-productivity wells , and drilling of E–W horizontal wells. The following results are achieved based on the practice. First, by virtue of seismic inversion of the Poisson ratio, thick sandstones can be identified effectively (the Poisson ratios of sandstone are 0.19–0.25, and those of shale are 0.27–0.30), and the distribution of major channel belts can be understood. Second, the central part of a river can be identified quickly by extracting the thickness of the net sand (GR < 60 API, effective porosity > 6%, and gas saturation > 60%) in the chessboard well pattern. Third, it is clarified that two types of superposed channel belts are developed in this block, and five types of sedimentary facies and ten channels subfacies are identified. Fourth, analysis on dynamic-static well parameters shows that the typical configuration of high-productivity wells in He 8 Member of Lower Shihezi Fm, Upper Paleozoic (the EUR > 1×108m3) is low GR (< 40 API), high effective porosity (> 10%) and high deep resistivity (> 90 Ω·m). And fifth, it is favorable for the lateral communication of multi-stage channels by arranging E–W horizontal wells in the central area of main braided channel belts. It is concluded that this set of key technologies for well location deployment deepens cognitions on the geological laws of fluvial reservoirs in this block and provides effective supports for the development and construction of this cooperation block.