Formation conditions of Neogene large-scale high-abundance lithologic reservoir in the Laibei low uplift, Bohai Sea, East China

Abstract

Abstract By using drilling, high-precision 3D seismic data, data of geochemistry, logging and testing, the reservoir characteristics and accumulation conditions of the KL6-1 lithologic oilfield in the Laibei Low Uplift in the Bohai Sea are examined comprehensively. The study shows that: KL6-1 oilfield is a monolithic, high-quality, large-scale Neogene lithologic oilfield featuring shallow reservoir depth, high productivity, concentrated oil-bearing intervals, large oil-bearing area, and high reserve abundance; hydrocarbon source supply from two directions provides a sufficient material basis for the formation of large oil field; two types of “inherited structural ridge” developed under the effect of block rotation, late active faults formed by Neotectonic movement, and widely distributed contiguous sand bodies provide an efficient oil and gas transportation system for the large-scale accumulation of oil and gas; contiguous channel and lacustrine lowstand system sand bodies developed in low accommodation condition provide the basic condition for the formation of large-scale lithologic traps; deep formations structural ridge, faults (dominant migration pathways) and large-scale superimposed contiguous sand bodies constitute a “vine type” oil and gas migration and accumulation system in the Laibei Low Uplift, which is conducive to the formation of large-scale and high-abundance lithologic reservoir in this area. The successful discovery of KL6-1, 100 million ton reserve order lithologic oil field, has revealed the exploration potential of Neogene large lithologic reservoirs in Bohai Sea, expanded the exploration field, and also has certain reference significance for the exploration of large lithologic reservoirs in similar areas.