Oil & Gas Geology ›› 2020, Vol. 41 ›› Issue (5): 928-940.doi: 10.11743/ogg20200504

• Petroleum Geology • Previous Articles     Next Articles

Lithological combination, genesis and exploration significance of the Lower Cambrian Wusonggeer Formation of Kalpin area in Tarim Basin: Insight through the deepest Asian onshore well-Well Luntan 1

Tianfu Zhang1,2(), Lili Huang1,2,*(), Xinfeng Ni1, Ran Xiong1,2, Guo Yang3, Guangren Meng2, Jianfeng Zheng1, Wei Chen1   

  1. 1. Hangzhou Institute of Geology, PetroChina, Hangzhou, Zhejiang 310023, China
    2. Tarim Research Center of Petroleum Exploration & Development Research Institute, PetroChina, Korla, Xinjiang 841000, China
    3. Tarim Oilfield Company, PetroChina, Korla, Xinjiang 841000, China
  • Received:2020-03-31 Online:2020-10-28 Published:2020-10-22
  • Contact: Lili Huang E-mail:zhangtf_hz@petrochina.com.cn;huangll_hz@petrochina.com.cn

Abstract:

The Wusonggeer Formation is a set of dolostone adjoining the gypsum pool of the Middle Cambrian.Its lithological combinations and genesis are therefore of great significance to the exploration strategy transition from "approaching source rocks" of the Lower Cambrian to "gypsum or gypsum-related strata" of the Middle Cambrian in the Tarim Basin.The study investigates the lithology and reservoir space types and discusses the sedimentary facies evolution and reservoir forming mechanisms in the Wusonggeer Formation of the Keping area through observation of outcrops and analyses of representative wells.The result shows that the Wusonggeer Formation in the Keping area is dominated by tidal flat facies of the mixed flat with terrigenous clastics and carbonates, dolomitic flat, gypseous-dolomitic flat and grain shoal flat, lithologically corresponding to the terrigenous clastic dolomite, argillaceous dolomite, granular dolomite, muddy-silty algal dolomite, stromatolite dolomite and etc.The algae-related dolomites including the grain dolostone, silty alga dolostone, and stromatolite dolostone, provide most reservoiring space with their intergranular and intragranular dissolved pores.The grain shoal was developed in the intertidal high-energy zone during a transgression against a tidal flat environment and contains intergranular pores dissolved by atmospheric fresh water during a penecontemporaneous stage.The silty algae dolostone was mainly developed in the dolomitic tidal-flat and gypsum dolomitic tidal-fat environment and contains intercrystalline pores and intercrystalline dissolved micro-pores due to microbial-induced dolomitization and dissolution of soluble substances like gypsolyte.Based on an integration of the tectonic high characterization, tidal flat settings of gypsolyte, lithological combinations and genesis of the Wusonggeer Formation in the Keping area, we identified six potential exploration targets in the periphery of several paleo-uplifts in the south of Tarim Basin and the south of Luntai and Yaha areas.

Key words: grain shoal, tidal flat, microbial induction, lithological combination, Wusonggeer Formation, Lower Cambrian, Tarim Basin

CLC Number: