Tectonic evolution and its control on differential hydrocarbon enrichment of Guxi Buried Hill， Jiyang Depression

Abstract

In order to clarify the differential hydrocarbon enrichment characteristics in Guxi Buried Hill of Jiyang Depression and guide the subsequent hydrocarbon exploration， the geological characteristics of the buried hill were analyzed based on the drilling and seismic data， and the tectonic evolution of the buried hill and its control on differential hydrocarbon enrichment were studied. The results show that Guxi Buried Hill has experienced four stages of compression， two stages of extension， two stages of strike-slip， and five stages of denudation since Indochina， which are the extrusive uplift and denudation in the Late Triassic， the weak extrusion to“cut bump and fill concave” in the early-middle Jurassic， the extrusive uplift and denudation in the Late Jurassic， the left-walking slip and stretch in the early Cretaceous， the extrusive uplift and denudation in the Late Cretaceous， and the right-walking slip and stretch and the denudation on the high buried hill in the Paleogene. In addition， according to the settlement in the Neogene， two kinds of buried hills such as high buried hills and low buried hills have been formed. The whole structure is characterized by “NW-trending fault controlling belts， NE （EW）-trending fault controlling hills， and alternating horst and graben”. The superimposition of multi-stage tectonic activities has resulted in obvious differences in source-reservoir connection， reservoir types， and hydrocarbon accumulation characteristics between the two types of buried hills. The stratigraphic reservoirs in the upper Paleozoic and Mesozoic are the most abundant in the high buried hills. All layers in the low buried hill can form reservoirs， and the tectonic reservoirs in Paleozoic strata are the most abundant. The hydrocarbon enrichment characteristics of the same type of buried hills are also different due to the different allocation of reservoir-forming factors. The stratigraphic reservoirs at the slope zone of high buried hills in Chengzhong， Chengdong， and Gudao， the weathering crust reservoirs and interior tectonic reservoirs of Lower Paleozoic， and the tectonic reservoirs of Upper Paleozoic and Mesozoic in low buried hills of Gubei and Kenli are the key targets for subsequent exploration.

Keywords

• tectonic evolution
• differential enrichment
• reservoir-forming pattern
• guxi buried hill
• jiyang depression