Accumulation Models Of Paleogene Reservoirs In The Kaiping Sag,Zhu I Depression,Pearl River Mouth Basin

As the next major direction of the Pearl River Mouth Basin,the Paleogene ultradeep reservoirs have complex oil and gas source relationship and various hydrocarbon transmission modes.In this paper,the Paleogene reservoirs in Kaiping Depression were taken as the research target,and started from the static reservoir formation conditions of the Paleogene reservoirs,and a systematic study on the distribution of oil and gas reservoirs,oil and gas sources,reservoir formation periods and oil and gas transmission system were carried out,and the hydrocarbon sources of the Paleogene reservoirs in Kaiping area were clarified,the main reservoir formation periods and recover the transmission system and reservoir formation process in different reservoir accumulation periods were determined,and the four types of reservoir formation patterns were summarized.The results showed that the stratigraphic conditions in Kaiping are normal temperature and pressure,and the main reservoirs are tectonic reservoirs,distributed in the Enping Formation and the Upper Wenchang Formation;the main reservoir space in the Paleogene is intergranular pore,and three sets of caprock are developed: the regional caprock of the Zhujiang Formation and the direct caprock of the Enping and Wenchang Formations;the main hydrocarbon source rocks are the shallow lacustrinesemi deep lacustrine mudstones in the upper Wenchang Formation and the deep lacustrine-semi deep lacustrine mudstones in the lower Wenchang Formation;the main The main types of crude oil are deep lacustrine-semi deep lacustrine crude oil,shallow lacustrine-semi deep lacustrine crude oil and the mixture of both;fluid inclusion and hydrocarbon generation simulation showed that there are two phases of accumulation:Phase I: 16 Ma～10 Ma and Phase II: 6 Ma～0 Ma;in the first stage,due to the shallow burial depth,high porosity of the reservoir and active faults,the deep lacustrine crude oil was transported upward along the faults and concentrated in the remote source.In the second stage,the reservoir porosity decreases due to the burial depth and the faults were basically inactive,so the shallow lacustrine crude oil could only be transported towards the adjacent sand bodies or slowly transported into the adjacent layers through the inactive faults.There are four main modes: early active faults vertical transport and distant source accumulation modes,early sand bodies-faults coupled vertical transport and distant source accumulation models,late sand bodies transport and near source accumulation models,and late faults transport and near source accumulation models.