Well Analysis of Information from Drilled Wells and Revelation to Oil & Gas Exploration in Jiaojiang Sag

The analysis of information from the drilled wells is an important procedure in oil and gas exploration, and the analysis result is directly related to the determination of exploration direction in some region. Based on the analysis of geological information from 5 wells drilled in Jiaojiang Sag, it can be concluded the failures were resulted by physical properties of reservoir, effectiveness of trap and migration path. In Jiaojiang Sag, the deep lacustrine facies mudstone of Paleocene Yueguifeng Formation is the major source rock, the shallow sea mudstone of Lingfeng Formation and coal-bearing formation of Mingyuefeng Formation, with limited ability of hydrocarbon generation, are auxiliary. There are four reservoir-cap assemblages in the study area. It is diffcult for the hydrocarbon generated from the matured source rock in the center of the sag to migrate through the thick mudstone of Lingfeng Formation and lower Mingyuefeng Formation to the middle and upper assemblages. The effective and favorite assemblages, therefore, are the lower assemblage in Yueguifeng Formation and buried hill. The authors recommend that in the future exploration we should determine the advantageous hydrocarbon generation center at frst, make clear the distribution of reservoir with good physical property, and choose the trap that is near source rock and with good migration condition as the preferential target. The main attention should be mainly focused on the assemblage in Yueguifeng Formation, with consideration to Mingyuefeng Formation and buried hill.