doi:10.16186/j.cnki.1673-9787.2020100027

Received:2020/10/14

Revised:2021/01/19

Published:2022/05/15

Analysis on controlling geological factors for peak gas production of CBM wells in Laochang blcok，eastern Yunnan Province

KANG Liuxu1,  HU Bin2, KANG Yongshang 1,3, ZENG Wenting4,  WANG Weihong 5, GU Jiaoyang2,6, TIAN Bofan1

1.Research Institute of China National Petroleum Corporation Xinjiang Oilfield Development Company ,Karamay 834000 , Xinjiang, China ;2.China United Coalbed Methane Co. , Ltd. , Beijing 100011 , China ;3.State Key Laboratory of Petroleum Resources and Prospecting of China University of Petroleum ( Beijing) ,Beijing 102249 , China ;4.Petro China Coalbed Methane Co. , Ltd. , Beijing 100028 , China ;5. Beijing Youyuan Hengye Technology Co. , Ltd. , Beijing 102200 , China;6.Unconventional Oil & Gas Branch , China National Offshore Oil Corporation, Beijing 100011 , China

Abstract:Based on the geological data and dynamic data of CBM from six pilot wells in the Laochang block， on the basis of the analysis of water and gas production characteristics，the main geological factor sand influencing mechanism that influenced the coalbed methane drainage effect in the Laochang block were disscussed , and the lower limit index of the main geological factors and suggestions for well layer selection were put forward. The results showed that:(1)The producing resource abundance ,the average gas saturation and the average permea- bility of the coal seam were the three main geological factors controlling the peak gas production;The three factors worked together to control the peak production of coalbed methane;(2)Gas saturation affected the dynamic permeability at and after gas breakthrough by controlling the reduction of bottom hole flow pressure at gas breakthrough , which had an impact on peak production. Higher gas saturation was conducive to gas break- through at lower bottom hole flow pressure reduction , and was conducive to maintaining higher dynamic permeability ,which conducive to gas production and achieving higher peak gas production; (3 ) Under the background of low permeability coal reservoir in the Laochang block, the lower limit of production resource abundance was 1 x10⁸ m³/km² , the lower limit of gas saturation was 70% ,and the lower limit of permeability was 0.08 mD.If the gas saturation reached more than 90% , the lower limit of permeability could be reduced to 0.03 mD. It was suggested that in the future , when optimizing the well layers in the old plant area,it was needed to avoid the influence of faults,and under the guidance of the structural model , to select the well positions far away from faults; When selecting the multi-seam drainage and mining coal seams, the abundance of produced resources of 1 x10⁸ m³/km² should be taken as the lower limit,taking the average gas saturation of produced coal seams of 70% should be taken as the lower limit,and the average permeability of 0.08 mD should be taken as the lower limit.

Key words:Laochang block;multi-seam drainage;peak gas production;producing resource abundance;average gas saturation;average permeability

滇东老厂区块煤层气井峰值产气量主控地质因素分析_康刘旭.pdf