Hydrocarbon Forming Pattern And Favorable Block Prediction Of Putaohua Formation In The North Of Gaotaizi Oilfield

With the successive exploitation of the main area of the Putaohua formation in the Gaotaizi oilfield,the lithology reservoir of the Putaohua formation in the extended region in the north of the area has been a main reserve replacement target.However,the oil-water distribution of the region is very complicated.At present,there isn't any macroscopic overall understanding and meticulous research in the area.Based on the high-resolution sequence stratigraphy,petroleum geology, sedimentology and other related disciplines,this paper mainly studied the palaeostructure evolution,the migration field of the ancient oil and gas,the sedimentary characteristics of the reservoir, the oil-water distribution and the regulations and patterns of the hydrocarbon accumulation.Based on the theory of the palaeostructure recovery,this article systematically studied palaeostructure evolution on the top of the Putaohua formation in various period.The five stages of palaeostructure evolution on the top of the Putaohua formation were summed up and the key period of the hydrocarbon accumulation is the final phase of the Mingshui layer,initial discovered the ancient nose structure of the northern Gaotaizi in the key period of the hydrocarbon accumulation.Combined with the migration field of the ancient oil and gas,the blank region in the southwest of the study area is the favorable taget region of the hydrocarbon enrichment.By analysing the facies of the coring well,we can draw a concluded that the study region mainly developed the delta front subfacies included the submerged branch channel,sand sheet and the submerged branch interchannel microfacies and so on.By using the high-resolution sequence stratigraphy,studied the fine plane microfacies,established the sequence-stratigraphic framework of the Putaohua formation in Gaotaizi oilfield.Using the technology of he oil-water comprehensively analysis and trace,combined with the data of the structure,depositon,reservoir,oil test and log interpretation,this paper analysed the controlling factors of the oil-water distribution,considered that sand and the combination of the sand and fault controls the oil-water interface,the single trap has the unite oil-water interface.By dissecting the typical oil and gas reservoir,it was founded that the single local structures is the main controlling oil factors in the area,and two kinds of the patterns of the hydrocarbon accumulation were summed up.From the research above,the favorable region can be predicted,it can provide the suggestion for the extended edge of the development region and for filling the space.