Oil & Gas Geology ›› 2023, Vol. 44 ›› Issue (5): 1141-1158.doi: 10.11743/ogg20230506

• Petroleum Geology • Previous Articles     Next Articles

Development model and significance of favorable lithofacies association of sandy braided river facies of the Cretaceous Bashijiqike Formation in Zhongqiu 1 well block, Kuqa Depression, Tarim Basin

Zhiyong GAO1(), Yongping WU2, Zhaolong LIU1, Cong WEI2, Yongzhong ZHANG1, Cuili WANG2, Qunming LIU1   

  1. 1.Research Institute of Petroleum Exploration and Development,PetroChina,Beijing 100083,China
    2.Exploration and Development Research Institute of Tarim Oilfield Company,PetroChina,Korla,Xinjiang 734000,China
  • Received:2023-02-15 Revised:2023-05-10 Online:2023-10-19 Published:2023-10-19

Abstract:

The deep Cretaceous Bashijiqike Formation in well Zhongqiu 1 in the Kuqa Depression tested high flow rate of natural gas. However, due to the small number of wells, large burial depth, and strong reservoir heterogeneity, it is difficult to evaluate the favorable reservoirs in the area and analyze the control factors of differential well productivity. Based on the isochronous characteristics of flood surface, we establish an isochronous stratigraphic framework of Bashijiqike Formation through the analysis of core sedimentary facies and identification of facies markers. The evolution process of progradation (lake level descending) of braided river delta front, plain, and alluvial plain braided river is established from bottom to top in the three internal sedimentary units. In Zhongqiu 1 well block, the reservoir intervals showing productivity difference occur in the upper Ba 2 Member and Ba 1 Member which are mainly deposited in the sandy braided rivers on alluvial plain above the maximum flooding surface, and the main river channel has been in different positions in different periods during their deposition. Taking into account factors such as sedimentary microfacies, coarse and fine structure of detrital particles, pore types and characteristics, porosity and permeability data, and fracture intensity, the sandy braided river sedimentary bodies of the Bashijiqike Formation can be divided into nine types in terms of lithofacies combination, with the differences in sedimentary microfacies serving as the basis, and types I—V being favorable lithofacies combinations. A favorable lithofacies combination development model is built for the sandy braided river facies of the Bashijiqike Formation in the Zhongqiu 1 well block. The proportion of favorable lithofacies combinations in this area featuring high in the east and low in the west, serves to determine the differences in gas bearing properties. It is predicted that the SN-trending area between the eastern line across wells Zhongqiu 101, Zhongqiu 1, and Zhongqiu 104 and the western line across wells Zhongqiu 102 and Zhongqiu 2, is favorable for the development of large-scale effective reservoir, especially on the north and northeast sides.

Key words: sandy braided river, productivity difference, lithofacies combination, deep sequence, Bashijiqike Formation, Cretaceous, Zhongqiu 1 well block, Kuqa Depression

CLC Number: