Application of NMRL to the Evaluation of Low-Porosity and Low-Permeability upper Triassic Reservoirs in the Central Sichuan Basin
详细信息
- 责任者：Hu Yawu (Logging Company of of Chuanqing Drilling Engineering Co. ; CNPC ; Chongqing 400021 ; China) ; Yang Jia
- 刊名：Natural Gas Industry
- 出版年：2012
- 卷期：32(3)
- 关键词：核磁测井 ; nuclear magnetic logging ; 储层评价 ; reservoir evaluation ; 四川盆地 ; Sichuan Basin
- 页码：p.45-48
- 图表：1 illus., 2 tables, 12 refs.
- 分类号：1600
- issnNo：ISSN1000-0976
- isbnNo：CN51-1179/TE
摘要
The upper Triassic Xujiahe reservoirs in the central Sichuan Basin are typical clastic reservoirs with low porosity and low permeability so it becomes difficult to identify effective reservoirs,calculate reservoir parameters,or discriminate reservoir fluid types.In order to solve these problems,the following measures are taken.(1) The interpretation of nuclear magnetic resonance logs(NMRL) is integrated with core analysis and the spectrum coefficient method is used to rebuild capillary irreducible water porosity model with an absolute error below 0.5%.(2) The NMRL permeability model is optimized with the core data to improve the accuracy of permeability calculation.(3) The Archie equation is integrated to build a free water saturation model.Based on the accurate calculation of reservoir parameters,formation test data are applied to establish the criteria of reservoir identification.(4) Reservoirs with effective porosity over 6%and permeability over 0.05mD are effective reservoirs;those with the mean value of free water saturation below 10%and its maximum value below 15%are gas-bearing reservoirs;while those with the mean value of free water saturation over 15%and its maximum value over 20%are water layers.The statistics of 11reservoir intervals in 5wells reveal that the identified effective reservoirs match the formation test results and the coincidence rate of reservoir fluid discrimination is over 85%.