Petroleum Reservoir Evaluation and Development ›› 2022, Vol. 12 ›› Issue (4): 626-632.doi: 10.13809/j.cnki.cn32-1825/te.2022.04.010

• Field Application • Previous Articles     Next Articles

Cause analysis and treatment of coal-bed gas well plugging decline: A case study of southern Yanchuan CBM Field

LIU Xiao1(),CUI Bin1,WU Zhan2   

  1. 1. Linfen Coalbed Methane Branch of Sinopec, Linfen, Shanxi 041000, China
    2. Sinopec East China Oil and Gas Company, Nanjing, Jiangsu 200019, China
  • Received:2022-05-10 Online:2022-08-26 Published:2022-09-02

Abstract:

In the production process, part of the wells in southern Yanchuan CBM Field has the plugging characteristics of abnormal and rapid decline of gas production and liquid production. In order to analyze the causes of blockage, based on the changes of the production dynamic information of the liquid recovery, water quality and pump check of wells, the main cause of plugging is clarified, including scaling and pulverized coal. On the basis of analyzing the formation mechanism of scaling and pulverized coal blockage, the targeted prevention and treatment measures are carried out. For the scaling plugging wells, form a treatment measure combining the normal prevention by adding scale inhibitor and the plugging removal by multi-stage pulse shock wave. 16 wells implemented by multi-stage pulse shock wave have got a good production increase with an average production increase of 30.11×104 m3 per well. For the pulverized coal plugging wells, coal-carrying process by self-circulation and hollow rod well washing, and nitrogen foam well-unblocking treatment measures are formed. Well washing for carrying pulverized coal effectively alleviate the pump check caused by pulverized coal blocking pump, the gas well repair free period extended by 60 %. Four wells applied the nitrogen foam for unblocking achieve significant production increase, with an average daily production increase of 1.25×104 m3 per well. The results provide references for the cause analysis and treatment of blocked CBM wells.

Key words: deep coal seam, pulverized coal, scale formation, plugging, plug removal

CLC Number: 

  • TE37