The Study On The Ordovician Palaeo-karst Geomorphology And Reservoir Characteristics Of Shan384~shan400 Well Block Of Jingbian Gas Field

Paleokarst landform plays an important part in the development and distribution of carbonate paleo-weathered crust reservoirs of high-quality. For a long time it has been lack of profound and detailed study on paleokarst landform restoration and its controlling effects on reservoirs Gas reservoirs of Shan384 well block which mainly developed at the top of the Ordovician weathering crust in Jingbian Gas Field. Based on the combination of drilling data, logging data, analytical experiments and production records, this thesis tries to reconstruct the ancient landscape and explores its controlling effects on reservoirs. Several conclusions can be drawn as follows:1. The preservation of the fifth member of Majigou Formation varies from place to place. In general, the layers in northwestern part of Shan384 have been subjected an intensive erosion, the southeastern parts relatively complete.2. The reservoir spaces are mainly dissolved pore, intracrystalline pore, microfissure and gypsum mould pore. With higher permeability and porosity, Ma513 and Ma541 a are selected as target layers of the studying area.3. With comprehensive application of impression method, residual thickness method and paleogeological map, it is discovered that in the studying area there are three types of paleogeomorphologic units——Karst hill, Karst depression and Karst slope. In the area of the Karst hills, due to strong epigenic karstification, epigenetic karst belt, vertical vadose belts and horizontal undercurrentbelt are widely developed in the layer of Ma513. However, in the area of the Karst depression, the same things happened in the layer of Ma541 a. The difference is epigenetic karst belt and vertical vadose belt are less common.4. Through information from well-drilling and logging data, porosity-permeability testing and production records, it is confirmed that the most important target layer is Ma513 in Karst hills, and the second is Ma541 a in the Karst depressions. Accordingly, a forecast has been done on the basis of these research findings.