Xinjiang Petroleum Geology ›› 2022, Vol. 43 ›› Issue (4): 456-462.doi: 10.7657/XJPG20220411

• RESERVOIR ENGINEERING • Previous Articles     Next Articles

Production Mechanism of Mud and Sand in Ordovician Carbonate Reservoirs in Halahatang Oilfield, Tarim Basin

BAI Xiaofei1a(), ZHOU Bo2, DONG Changyin2(), WANG Fangzhi1a, LIU Xiao1b, GAN Lingyun2, REN Jinming1a   

  1. 1. PetroChina Tarim Oilfield Company, a.Research Institute of Oil and Gas Engineering; b.Development Department of Donghe Gas Field, Korla, Xinjiang 841000, China
    2. School of Petroleum Engineering, China University of Petroleum, Qingdao, Shandong 266580, China
  • Received:2021-04-23 Revised:2022-03-04 Online:2022-08-01 Published:2022-07-26
  • Contact: DONG Changyin E-mail:baixf-tlm@petrochina.com.cn;dongcy@upc.edu.cn

Abstract:

In order to clarify the mechanism of wellbore instability in the Ordovician reservoirs of Halahatang oilfield, the rock, sand particle size and mineral composition of washed-out sand samples were mainly analyzed. It is found that wellbore instability in the Ordovician carbonate reservoirs in the study area occurs in two modes: (1) collapse of wellbore in the upper unplugged non-producing horizon (Tumuxiuke formation), that is, macroscopic instability, which results in collapsed rock blocks; and (2) production of sand carried by the fluids from key producing horizons, that is, microscopic instability, which causes the wellbore blockage by sand and mud generated from the cracking of fracture fillings and the exfoliated fine-grained components from micro-convex. The main controlling factors of wellbore instability were analyzed with the grey relational method, indicating that reservoir burial depth, wellbore diameter, water cut and wellbore azimuth are the main factors affecting wellbore instability. The wellbore diameter, wellbore azimuth and production system can be optimized to prevent and control the production of mud and sand.

Key words: Tarim basin, Halahatang oilfield, Ordovician, carbonate rock, reservoir, wellbore instability, wellbore blockage, instability control

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