Diagnosis, prevention, and control of liquid accumulation in horizontal wellbores for deep coalbed methane: A case study of the Daning-Jixian block along the eastern margin of the Ordos Basin

Authors

ZENG Wenting, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China; National Engineering Research Center of China United Coalbed Methane Co., Ltd., Beijing 100095, ChinaFollow
WANG Zhiming, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China
ZHANG Lei, National Engineering Research Center of China United Coalbed Methane Co., Ltd., Beijing 100095, China
TIAN Zhida, National Engineering Research Center of China United Coalbed Methane Co., Ltd., Beijing 100095, China
ZHEN Huaibin, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China; National Engineering Research Center of China United Coalbed Methane Co., Ltd., Beijing 100095, China
DAI Anna, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China
ZENG Quanshu, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China
SUI Tianyang, College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102299, China

Abstract

Objective The Daning-Jixian block on the eastern margin of the Ordos Basin has achieved large-scale production of deep coalbed methane (CBM), with nearly 150 horizontal wells having been put into production. However, with a gradual decrease in formation energy during CBM production, gas wells exhibit declining liquid-carrying capacity. Consequently, liquid accumulation in wellbores has become a major factor affecting deep CBM production. Recovery of deep CBM shows the coexistence of free and desorbed gases, accompanied by significantly varying gas/liquid ratios. Moreover, gas production channels and techniques vary in different production stages. Hence, there is an urgent need to develop a method for liquid accumulation diagnosis and prediction that is suitable for the production characteristics of horizontal wells for deep CBM, aiming to provide a basis for the prevention and control of liquid accumulation and to avoid damage to reservoirs and their productivity caused by liquid accumulation. [Methods and Results] Using the Reynolds-averaged Navier-Stokes (RANS) κ-ε equation for incompressible viscous fluids and the volume of fluid (VOF) method, as well as the physical simulation experimental results of gas-liquid two-phase flow in a circular tube and an annulus, this study developed a numerical model of gas-liquid two-phase flow in horizontal wells for deep CBM utilizing the Fluent computational fluid dynamics tool and its secondary development. Based on the numerical simulation results, this study plotted the gas-liquid two-phase flow patterns in horizontal wells under different wellbore pressures, different inclinations, along with the circular tube and annulus conditions. Furthermore, this study established the corresponding relationship between the flow pattern and liquid accumulation based on the regularity and pattern evolution of gas-liquid two-phase flow in the production process. The results indicate that bubble and slug flows correspond to the liquid accumulation state. In contrast, churn flow corresponds to the transition state where liquid accumulation will occur, while annular flow corresponds to the state with no or low risk of liquid accumulation. Additionally, the well inclination is directly proportional to the liquid accumulation risk, whereas the pressure is inversely proportional to the risk. Conclusions The flow pattern chart board-based method for diagnosing liquid accumulation proposed in this study was applied to the horizontal wells for deep CBM in the Daning-Jixian block, providing guidance for proposing the intervention timing, taking control measures in time, with the efficiency of measures having been improved. In subsequent studies, this method will be optimized for intelligent analysis and prediction using artificial intelligence (AI) techniques. This will provide robust technical support for the prediction, prevention, and control of liquid accumulation in CBM wellbores.

Keywords

Ordos Basin, deep coalbed methane (CBM), gas-liquid two-phase flow pattern, volume of fluid (VOF) method, liquid accumulation prediction

DOI

10.12363/issn.1001-1986.25.03.0209

Recommended Citation

ZENG Wenting, WANG Zhiming, ZHANG Lei, et al. (2025) "Diagnosis, prevention, and control of liquid accumulation in horizontal wellbores for deep coalbed methane: A case study of the Daning-Jixian block along the eastern margin of the Ordos Basin," Coal Geology & Exploration: Vol. 53: Iss. 9, Article 7.
DOI: 10.12363/issn.1001-1986.25.03.0209
Available at: https://cge.researchcommons.org/journal/vol53/iss9/7

Reference

[1] 吴裕根，门相勇，娄钰. 我国“十四五”煤层气勘探开发新进展与前景展望[J]. 中国石油勘探，2024，29(1)：1−13.

WU Yugen，MEN Xiangyong，LOU Yu. New progress and prospect of coalbed methane exploration and development in China during the 14^th Five–Year Plan period[J]. China Petroleum Exploration，2024，29(1)：1−13.

[2] 徐凤银，闫霞，李曙光，等. 鄂尔多斯盆地东缘深部(层)煤层气勘探开发理论技术难点与对策[J]. 煤田地质与勘探，2023，51(1)：115−130.

XU Fengyin，YAN Xia，LI Shuguang，et al. Theoretical and technological difficulties and countermeasures of deep CBM exploration and development in the eastern edge of Ordos Basin[J]. Coal Geology & Exploration，2023，51(1)：115−130.

[3] 徐凤银，侯伟，熊先钺，等. 中国煤层气产业现状与发展战略[J]. 石油勘探与开发，2023，50(4)：669−682.

XU Fengyin，HOU Wei，XIONG Xianyue，et al. The status and development strategy of coalbed methane industry in China[J]. Petroleum Exploration and Development，2023，50(4)：669−682.

[4] 张琪，周生田，吴宁，等. 水平井气液两相变质量流的流动规律研究[J]. 石油大学学报(自然科学版)，2002，26(6)：46−49.

ZHANG Qi，ZHOU Shengtian，WU Ning，et al. Laws of gas–liquid two–phase variable mass flow in horizontal wellbore[J]. Journal of the University of Petroleum，China，2002，26(6)：46−49.

[5] 汪志明. 复杂结构井完井优化理论及应用[M]. 北京：石油工业出版社，2010.

[6] WANG Zhiming，ZHANG Quan，ZENG Quanshu，et al. A unified model of oil/water two–phase flow in the horizontal wellbore[J]. SPE Journal，2017，22(1)：353−364.

[7] TAITEL Y，BARNEA D，DUKLER A E. Modelling flow pattern transitions for steady upward gas–liquid flow in vertical tubes[J]. AIChE Journal，1980，26(3)：345−354.

[8] BARNEA D，SHOHAM O，TAITEL Y，et al. Gas–liquid flow in inclined tubes：Flow pattern transitions for upward flow[J]. Chemical Engineering Science，1985，40(1)：131−136.

[9] SCHMIDT J，GIESBRECHT H，VAN DER GELD C W M. Phase and velocity distributions in vertically upward high–viscosity two–phase flow[J]. International Journal of Multiphase Flow，2008，34(4)：363−374.

[10] SZALINSKI L，ABDULKAREEM L A，DA SILVA M J，et al. Comparative study of gas–oil and gas–water two–phase flow in a vertical pipe[J]. Chemical Engineering Science，2010，65(12)：3836−3848.

[11] OZAR B，JEONG J J，DIXIT A，et al. Flow structure of gas–liquid two–phase flow in an annulus[J]. Chemical Engineering Science，2008，63(15)：3998−4011.

[12] JULIA J E，HIBIKI T. Flow regime transition criteria for two–phase flow in a vertical annulus[J]. International Journal of Heat and Fluid Flow，2011，32(5)：993−1004.

[13] MONNI G，DE SALVE M，PANELLA B，et al. Electrical capacitance probe characterization in vertical annular two–phase flow[J]. Science and Technology of Nuclear Installations，2013，2013(1)：568287.

[14] 吴绍伟. 垂直环空气液两相流理论及在油井生产中的应用[D]. 青岛：中国石油大学(华东)，2009.

WU Shaowei. Theoretical investigation of upward gas–liquid two–phase flow in annuli and applications in the process of production in oilfield[D]. Qingdao：China University of Petroleum (East China)，2009.

[15] 张旭鑫. 垂直环空油基钻井液–气体两相流流型转化规律研究[D]. 青岛：中国石油大学(华东)，2020.

ZHANG Xuxin. Study on flow pattern transition of oil based drilling fluid–gas two–phase flow in vertical annulus[D]. Qingdao：China University of Petroleum (East China)，2020.

[16] 郝晶晶，马孝义，王波雷，等. 基于VOF的量水槽流场数值模拟[J]. 灌溉排水学报，2008，27(2)：26−29.

HAO Jingjing，MA Xiaoyi，WANG Bolei，et al. Numerical simulation of flow field in flow–measuring flume based on VOF method[J]. Journal of Irrigation and Drainage，2008，27(2)：26−29.

[17] 董志，詹杰民. 基于VOF方法的数值波浪水槽以及造波、消波方法研究[J]. 水动力学研究与进展，2009，24(1)：15−21.

DONG Zhi，ZHAN Jiemin. Comparison of existing methods for wave generating and absorbing in VOF–based numerical tank[J]. Journal of Hydrodynamics，2009，24(1)：15−21.

[18] 张雷，边利恒，侯伟，等. 深部煤储层孔隙结构特征及其勘探意义：以鄂尔多斯盆地东缘大宁–吉县区块为例[J]. 石油学报，2023，44(11)：1867−1878.

ZHANG Lei，BIAN Liheng，HOU Wei，et al. Pore structure characteristics and exploration significance of deep coal reservoirs：A case study of Daning–Jixian Block in the eastern margin of Ordos Basin[J]. Acta Petrolei Sinica，2023，44(11)：1867−1878.

[19] 曾雯婷，徐凤银，张雷，等. 鄂尔多斯盆地东缘深部煤层气排采工艺技术进展与启示[J]. 煤田地质与勘探，2024，52(2)：23−32.

ZENG Wenting，XU Fengyin，ZHANG Lei，et al. Deep coalbed methane production technology for the eastern margin of the Ordos Basin：Advances and their implications[J]. Coal Geology & Exploration，2024，52(2)：23−32.

[20] 曾雯婷，葛腾泽，王倩，等. 深层煤层气全生命周期一体化排采工艺探索：以大宁–吉县区块为例[J]. 煤田地质与勘探，2022，50(9)：78−85.

ZENG Wenting，GE Tengze，WANG Qian，et al. Exploration of integrated technology for deep coalbed methane drainage in full life cycle：A case study of Daning–Jixian Block[J]. Coal Geology & Exploration，2022，50(9)：78−85.

[21] 王光付，李凤霞，王海波，等. 四川盆地不同类型页岩气压裂难点和对策[J]. 石油与天然气地质，2023，44(6)：1378−1392.

WANG Guangfu，LI Fengxia，WANG Haibo，et al. Difficulties and countermeasures for fracturing of various shale gas reservoirs in the Sichuan Basin[J]. Oil & Gas Geology，2023，44(6)：1378−1392.

[22] 王庆蓉，陈家晓，向建华，等. 页岩气井积液诊断及排水采气工艺技术探讨[J]. 天然气与石油，2020，38(5)：83−87.

WANG Qingrong，CHEN Jiaxiao，XIANG Jianhua，et al. Discussion on shale gas well effusion diagnosis and drainage gas production technique[J]. Natural Gas and Oil，2020，38(5)：83−87.

[23] 曾小军，廖刚，任文希. 四川页岩气开发排水采气技术优选[J]. 钻采工艺，2023，46(3)：176−179.

ZENG Xiaojun，LIAO Gang，REN Wenxi. Optimization of drainage and gas recovery technology for shale gas development in Sichuan Block[J]. Drilling & Production Technology，2023，46(3)：176−179.

[24] 唐淑玲，汤达祯，杨焦生，等. 鄂尔多斯盆地大宁–吉县区块深部煤储层孔隙结构特征及储气潜力[J]. 石油学报，2023，44(11)：1854−1866.

TANG Shuling，TANG Dazhen，YANG Jiaosheng，et al. Pore structure characteristics and gas storage potential of deep coal reservoirs in Daning–Jixian Block of Ordos Basin[J]. Acta Petrolei Sinica，2023，44(11)：1854−1866.

[25] 陈明，王大猛，余莉珠，等. 大宁–吉县区块深部煤层气井排采制度研究与实践[J]. 煤炭学报，2025，50(4)：2188−2197.

CHEN Ming，WANG Dameng，YU Lizhu，et al. Drainage system research and application of deep coalbed methane gas reservoirs in Daning–Jixian Block[J]. Journal of China Coal Society，2025，50(4)：2188−2197.

[26] 顾汉洋，高晖，郭烈锦. 水平管油水两相分层紊流流动的数值研究[J]. 工程热物理学报，2003，24(5)：810−812.

GU Hanyang，GAO Hui，GUO Liejin. Numerical study of stratified oil–water two–phase turbulent flow in a horizontal tube[J]. Journal of Engineering Thermophysics，2003，24(5)：810−812.

[27] 陈宇翔，郜冶，刘乾坤. 应用VOF方法的水平圆柱入水数值模拟[J]. 哈尔滨工程大学学报，2011，32(11)：1439−1442.

CHEN Yuxiang，GAO Ye，LIU Qiankun. Numerical simulation of water–entry in a horizontal circular cylinder using the volume of fluid (VOF) method[J]. Journal of Harbin Engineering University，2011，32(11)：1439−1442.

[28] YUAN G. Liquid loading problems of natural gas wells[D]. Tulsa：The University of Tulsa，2011.

[29] GUNER M，PEREYRA E，SARICA C，et al. An experimental study of low liquid loading in inclined pipes from 90° to 45°[C]//SPE Production and Operations Symposium. Oklahoma City：Society of Petroleum Engineers，2015：SPE–173631–MS.

[30] ALSAADI Y，PEREYRA E，TORRES C，et al. Liquid loading of highly deviated gas wells from 60° to 88°[C]//SPE Annual Technical Conference and Exhibition. Houston：Society of Petroleum Engineers，2015：SPE–174852–MS.

[31] SKOPICH A，PEREYRA E，SARICA C，et al. Pipe–diameter effect on liquid loading in vertical gas wells[J]. SPE Production & Operations，2015，30(2)：164−176.