Analysis High Resolution Sequence Stratigraphy Of Lower Cretaceous Of The Kubla Formation In Ronier Block, Bongor Basin, Middle Africa

Affected by regional economic situation and complex geological structure,Systematic oil and gas exploration and development in Bongor basin started late.Previous research has focused on the formation, structure, the influence of tectonic movement on the reservoir and the evaluation of hydrocarbon source rocks of the entire Bongor basin region. It is not enough on sedimentary facies and the pattern of sequence of the key oil and gas reservoirs in the key area. In order to improve the understanding of kubla formation and reduction the sedimentary facies of kubla formation, it is quite important to research on the high resolution sequence stratigraphy. It can also solve the accuracy problem of oil and gas exploration on actual production. According to the actual production situation, lower Cretaceous of the kubla formation in Ronier block in Bongor Basin is the key formation of oil and gas reservoirs. This paper is trying to reduction the sedimentary facies in plane, divide high resolution sequence stratigraphy in vertical and track small layer sand body in horizontal. Combined with the previous research, based on drilling core date, thin section data, seismic data and logging data, establish the identification mark of sedimentary microfacies and conversion model between rock and electricity. Analysis the sedimentary microfacies, at the same time, confirm the identification mark of sequence and lake flood surface with different orders. Analysis the sequence stacking pattern and combination features of sequence with different orders. High-resolution sequence stratigraphy isochronous stratigraphic framework is established by making the short-term base level cycle as isochronous stratigraphic unit and the mid-term base level cycles as isochronous stratigraphic framework. Track and contrast the oil formation and small layer sand body in horizontal. Establish the sedimentary facies model, at the same time, draw up plane distribution maps of sedimentary facies of different sequence. Analysis the characteristics of sedimentary facies in different sedimentary periods, find out the distribution characteristics and influence factors of sand body. Fan delta sedimentary system and lake sedimentary system are developedduring the Kubla formation sedimentary periods, which including fan delta fornt subfacies and littoral and shallow lake subfacies. Fan delta fornt subfacies include underwater division channel, underwater natural levee, split bay, mouth bar. Kubla formation can divide into 2 long-term, 4 middle-term, 19 short-term base level cyclic sequences. Analysis the sedimentary characteristics and distribution of sand body in each sedimentary period. The sand body extension direction along the NE-SW, is the same to the underwater microfacies. In the vertical direction, the sand body thickness in the later MSC2 and early MSC3 is larger, and the content of sand body was higher than others. Those areas are the key areas in the nest exploration and development.