Comprehensive Geological Research On C₄₊₅ Reservoir In Danba Area Of Zhidan Oil Field

The paper makes full use of geological,well-logging and indoor analysis and test data,and integrate well-logging sedimentology,petroleum geology and computer technology with theory of traditional paleontology and sedimentology,according to research thoughts that from macroscopic to microscopic,from single well-Multiple well to target stratum in the research region, have studied the property of microcosmic pore structure, lithologic, sedimentary facies, petrophysical property and so on in-depth.Based on the content describe above, we sort the reservoir into three and evaluate the three types of reservoir,which Supply foundation to progressive exploration and increasing the effective exploitation.In the end,we achieve the following conclusion:1. Facies of C4+5Oil-bearing bed are lake delta,facies of C4+51is delta front and C4+52is delta plain. Sand bodies of C4+5Oil-bearing bed are mainly distributary channel deposits of lake delta front facies and delta plain facies.2. By analyzing the data of drilling cores and rock thin-section, we think that fine-grained feldspar sandstone is the main oil-bearing rock in C4+5reservoir of research region.3. We study the data of rock thin-section and SEM comprehensively,the research results indicated that C4+5sandstone in the research region is in the ’A’ period of later diagenesis.During diagenetic process,the diagenesis include compaction,pressure solution,cementation, metasomasis and dissolution.4. By analyzing the measured physical properties data of drilling cores, we achieve that its reservoir physical characteristics is poor,the main reservoir is low porosity, extremely-low porosity and permeability reservoirs.5. Based on analysed rock cast sections and mercury intrusion data, we think pore types in C4+5reservoir of research region include intergranular pores, distinguishable secondary dissolved pores,intercrystalline pores,the main pore types is intergranular pores. Mainly pore structure types in C4+5reservoir are small pore with medium-fine throat and small pore with microthroat.6.We evaluated reservoir and divide reservoir in C4+5of research region into three,namely I(good reservoir)、Ⅱ(medium reservoir)、Ⅲ(poor reservoir).