Evaluation Of Reservoir Characteristics In Shan 2~3 Of Shanxi Formation In Zizhou Area Of Ordos Basin

Ordos Basin , which is one of the biggest landlocked sedimentary basins and abundant in the gas and oil resources ,has a considerable potential for the exploration. zizhou area is located in the northeastern of Ordos Basin building block,the exploration of this area begins in the 1980s,after more than 20 years of research, zizhou gas filed has become one of the most important gas-producing districts of this area. There are many gas reservoirs has been found in this filed at present, and the second number of Shanxi formation gas reservoir is the optimum exploitation part of upperpalaeozoic, especially the Shan 2³ .However ,the zizhou gas filed Shan 2³'s geology composition-well logging is lack of study, and the opinions of sedimentary systems and sedimentary micro faces distribution are various,which cause the some contradictions between real and theory. For example, the thickness of sand and the physical property of some areas reach the standard, but the production of these areas are not satisfied. The present thesis launch a discussion on problems now existing in the gas reservoirs, and provide some evidences for sorting estimation and beneficial reservoir body prediction.Based on the process of core observation, boing well, well logging, analysis and examination, using he traditional geology research method .this thesis summarize the research findings of this area and its surroundings and launch the estimation of zizhou area Shanxi formation Shan 2³ reservoir.1)Referring to the research findings of sedimentary facies in this area, utilizing the electrical relationship combining the well logging curve to identify that zizhou area Shan 2³ is delta front laydown.the main style of reservoir is subsea distributary channel,it also has the advantages such as thick sandstone ,good continuity and reservoir property, mouth bar,sand sheet also have developed to some extent. On the basis of identifying and referring each microfacies,this thesis predict the seismic facies of Shan 2³ sedimentary fades.2)According to the physical properties, mercury injection data and the observation of cast thin sections, the average porosity of Shan 2³ sandstone is 5.59%,the average permeability is 2.66×10^-3 m²,which means that this area is a low porous, low permeable reservoir, the mean lithogical is quartz sandstone and cuttings sandstone, the research found that the physical property of the study area is better than cuttings sandstone , in contrast , the physical property degrade as the increasing of quartz sandstone. when pore type is residual intergranular pore, corrosion intergranular pore, intercrystal pore ,fracture pore or intergranular dissolution pore, the throat and the continuity are not satisfied. Reservoir is incentive to precipitation surroundings and digenesis, the dissolution makes contribution to reservoir ,the Compaction and cementation make the porosity and the permeability low.3)Concluding the research findings and referring to the well logging data ,this thesis summaries the well logging model ,which is fit for predicting the shale content, the porosity and the permeability data. Identifying the Shan 2³ gas-water based on the gas-water identify method, which provide great evidence for the coming prediction of this area.4)Combining the reservoir data of the study area with classification of the clastic rocks in Ordos Basin. The reservoir of the study area can be divided into three parts. Overall, styleⅡandⅢare the majority part of the reservoir of the study area, integrating the reservoir distribution analysis , reservoir physical property data with Determination of reservoir parameters and Referring to the gas-water distribution of study area in order to give a comprehensive assessment of the reservoir in zihou area Shan 2³ ,besides, make divisions of some Favorable Zones.