Quantitative Evaluation And Forecast Of Oil-bearing Probability Of Lithological Hydrocarbon Reservoir Of Es3 In Linnan Subsag

With the development of oil exploration, the concealments of residual petroleum resources are more prominent and lithological reservoirs have attracted much more attention in exploration field. After more than 40 years exploration on tectonic reservoirs, lithological reservoirs have become the next key targets in Linnan subsag, the most important subsag in Huimin sag. Exploration in the last few years indicates that the oil-bearing properties of lithological trap varies a lot, and to calculate the oil-bearing and oil-filling index has been an indispensable technique in making decision on oil fields exploration, locating wells, and developing oil pools. Now a reasonable and credible evaluation is badly needed to forecast the petroliferous properties accurately, which can improve the efficiency of oil exploration and meet the needs of lithological reservoir exploration.Based on the aim of establishing a model about the petroliferous properties in reservoirs and predicting favorable areas in Linnan subsag, this article selects three kinds of typical lithological reservoirs - lenticular reservoirs, upclined pinch-out reservoirs and structure-lithological reservoirs - at first, then analysis these reservoirs about the accumulation conditions at sand level, buries depth, structural location, sedimentary system, physical property of reservoir, trap-filling index, and petroliferous properties. The results suggests that sand bodies in all the three areas are benefit for the formation of oil pool, but the petroliferous properties varies.Furthermore, 14 sand bodies of lithological reservoirs in Linnan subsag are statistically analyzed in terms of the basic and structure properties of sand bodies, sedimentary properties, reservoir properties, petroliferous properties and so on. Combine with the analysis of typical pools, it is suggested that the main factors which dominate the formation of lithological pools in Linnan subsag are structural properties, sedimentary facies, oil generation and oil expulsion intension of source rocks, and reservoir conditions.On the basis of statistical analysis, the Analytic Hierarchy Process (AHP) is used to analyze the factors that influent the petroliferous properties of lithological reservoirs in Linnan subsag, and to determine the weights of each facter: the reservoir subsystem and the oil generation/expulsion subsystem of Linnan subsag determines the oil saturation, with its weights of 0.57 and 0.28, in which the buried depth is closely contacted to oil saturation. Reservoir and migration/accumulation subsystem effects obviously to the fullness of lithological oil pool in this area, with its weights of 0.5 and 0.26. Based on all of these, the petroliferous properties quantitative-predict model is established. Then petroliferous property model of lithological pool in Linnan subsag is established using the mathematical geology method of stepwise regression and culling variables. According to this model and combined with the major formation factors, five favorable targets of Jishan delta lithological oil pool is predicted, favorable zones are suggested -Jiangjiadian-wawu delta fit for lenticular reservoirs development, and Yingzijie zone for structure-lithological reservoirs formation.