川东北YB地区长兴组礁滩相储层测井评价技术

川东北YB地区上二叠统长兴组礁滩相储层裂缝及溶蚀孔洞发育，储集类型为溶蚀孔洞型和裂缝-孔洞型，气水关系复杂，储层有效性判别、流体性质识别及产能预测是礁滩相储层评价的难点。针对该区礁滩相储层的特征，阐述了成像和偶极测井是解决裂缝、溶蚀孔洞识别及有效性判别的最直接的方法；明确了不同饱和度下电阻率与孔隙度交会、核磁共振测井信息相结合是判别礁滩相储层流体性质的最有效的方法，尤其能解决裂缝引起的深、浅侧向负差异的流体性质识别难题；提出了礁滩相气层有效厚度与孔隙度乘积的累加可作为产能预测评价指标的认识。所形成的礁滩相储层测井评价技术将进一步为经济高效地开发YB地区长兴组气藏提供有力的技术支撑。

Logging evaluation technology of reservoirs of reef-shoal facies in the Changxing Formation in the YB area,northeastern Sichuan Basin

Fractures and caverns are well developed in the reservoirs of reef shoal facies in the Upper Permian Changxing Formation in the YB area, northeastern Sichuan Basin. The reservoir space is of dissolution cavern type or fracture vug type; and water gas contact is very complicated. Identification of effective reservoirs, determination of fluid property and prediction of gas deliverability are all big challenges during reservoir evaluation. In view of the reservoir features of reef shoal facies, this paper presents image logging and dipole logging as the most direct methods for identifying fractures, caverns and effective reservoirs. Cross plotting of resistivity vs. porosity at different saturations and integration with NMR logging data are the most effective ways to determine the fluid property of reservoirs of reef shoal facies, and in particular to solve the problem of fluid property discrimination when there exist deep and shallow lateral negative differences caused by fractures. The sum of products of net thickness and porosity can be used as the criteria for evaluating the deliverability of gas reservoirs of reef shoal facies. The logging evaluation technology for reservoirs of reef shoal facies will provide robust technical support for economic and effective development of gas reservoirs in the Changxing Formation in the YB area.