Analysis Of Main Controlling Factors Of Petroliferous Property And Favorable Area Prediction Of Changxing Formation In The Northeastern Sichuan Basin

The Upper Permian Changxing Formation is a very important exploration horizon in northeastern Sichuan Basin.So far,Puguang,Yuanba and Longgang gas fields have been discovered,which have broad exploration prospects.However,the current research is mainly focused on a single gas field,and there is a lack of overall research on the platform margin of the Kaijiang-Liangping Trough,including Puguang,Yuanba and Longgang gas fields.With the emergence of multiple failure wells,more in-depth understanding is needed.This paper firstly analyzes the geological characteristics of typical gas reservoirs in northeastern Sichuan,and the characteristics of gas reservoir formation and distribution are analyzed.On this basis,the main controlling factors of gas accumulation in Changxing Formation are defined.Finally,the favorable zones of different types of gas accumulation in the study area are defined by using the method of functional factor grouping for prediction.The results show that: the formation and distribution of natural gas reservoirs in northeastern Sichuan is jointly controlled by six geological factors: source rock,sedimentary facies,regional cap bed,fault,paleo-uplift and low potential area.Through further study,it is realized that the closer to the hydrocarbon generating center of source rock,the more developed high-quality reservoir,moderate cap bed thickness,the closer to the top of paleo-uplift,near the fault zone and low interface potential energy zone,the better the gas bearing capacity of Changxing Formation.And the best facies of natural gas accumulation are reef and platform margin.The evaluation criteria of each main controlling factor are determined,and the favorable areas are divided by functional factor grouping method.On this basis,different types of gas reservoirs are predicted.Finally,the most favorable reservoir forming zones of four fault tectonic type,five anticlinal tectonic types and five lithologic gas reservoirs are predicted,and the favorable reservoir forming zones of these three gas reservoirs are superposed,and then the fault-anticline-lithologic and anticlinal-lithology compound reservoir forming zones are pointed out.