Study On The Hydrocarbon Formation Controlling Factors Of Putao Flower Reservoir In Puxi Oilfield

The project team, on the basis of high-resolution sequence stratigraphy, goestatistics, geochemistry, geology and reservoir engineering, combines logging technology and seismic interpretation, and deepens understanding of Putaohua oil layer in Puxi oilfield, so as to solve new problems on complex sand body distribution and reservoir distribution. Based on short-term and medium-term datum plane cycle, Putaohua oil layers are divided into two subsequence series and seven subsequences (MSC1-MSC7), and MSC1- MSC2, MSC3-MSC5 and MSC6- MSC7 sedimentation models are put forward. Through the research on matching between fault active state and mudstone dehydration and reservoir formation period and the influence of distillation on reservoir formation, several points are brought forward as follows:oil reservoir and condensate gas reservoir are isogenous; hydrocarbon reservoir experienced such an complex process (reservoir formation- reservoir destruction- reservoir reformation); the distribution of oil, gas and water affects by faults in early and later stage and by abnormal high pressure; layers with both water and oil are dominant; condensate gas reservoir, which is in small scale and just gas cap in single sand body, distributes in the trap formed by lithological pinch-out. Strata cross-plot chart method, differential chart identification method, half-quantification cross-plot chart method and pyrolysis parameter interpretation method are put forward to identify oil wetting or water wetting layers with both water and oil. Distributary flow curves, calculated with relative permeability data, are corrected with sealing coring data, and interpretation method of water cut of layers with water and oil in the early stage of water flooding is pointed out. It suggests that low permeable reservoir keeps watercut steady in elastic development, and the higher the watercut is in the early stage of waterflooding, the more slowly the oil production declines, the more slowly the rate of water cut increases. Economic low limits corresponding to various watercut in the early stage are calculated, with the application of present development techniques. According to research on high resolution sequence stratigraphy and reservoir formation mechanism, with multi-parameter reservoir sorting evaluation method and seismic inversion method, Putaohua oilfield has optimized 3562×104 ton reserves with oil bearing area 138.0 km2, which would be exploited recently, and cancel geological reserves 1450×104 ton reserves after verification, with oil bearing area 49.0 km2. Project team has achieved great success in pilot test. In 2003 and 2004, team has designed total 23 development appraisal wells and 554 development wells, producing 1527×104 ton reserves, which accounts for total 43% of optimized reserves. By October 2004,166 wells are drilled with the well drilling success rate 99%, and 107 wells are on stream, and log interpretation coincidence rate is 88.5%.