PetroChina Coalbed Methane Company Limited
China United Coalbed Methane National Engineering Research Center Co., Ltd.
Chinese Petroleum Society
China University of Petroleum (Beijing)

相比中浅部煤层气，深部煤层气煤体结构较好、地层压力高、游离气占比较高、矿化度高、CO2含量高，实施大规模压裂投产后，初期可自喷，生产参数各阶段变化大，要求排采主体工艺技术边界宽；相比页岩气和致密气，由于产出机理不同、游离气占比相对较低，深部煤层气表现出自喷周期较短，需及时辅助排水采气措施，气井长期处于解吸主控的低产阶段。以鄂尔多斯盆地东缘大宁−吉县区块为例，基于深部煤储层地质特征，系统分析深部煤层气排采过程中应力敏感效应、速度敏感性、结垢堵塞、贾敏效应、游离气占比等影响因素及其特征，指出深部煤层气排采过程中存在游离气与解吸气转化时限不明、高矿化度水及CO2造成腐蚀和结垢问题突出、水平井检泵周期短等排采技术与工艺难点。为了最大限度降低井底压力、促进煤层气解吸、提高单井EUR，提出了现阶段最为适合水平井生产且经济效益最佳的水力射流泵举升工艺；提出了深部煤层气迈向绿色智慧气田开发的排采技术与举升工艺研究方向，包括加强地质工程一体化研究，建立高效排采制度，探索和试验无杆泵一体化排采工艺等。

Contrasting with shallow to moderately deep coalbed methane (CBM) reservoirs, deep CBM reservoirs exhibit favorable coal structures, high formation pressure, high free gas ratios, and high contents of total dissolved solids (TDS) and CO2. Extensive fracturing allows for CBM flowing at the initial stage, while the production parameters vary significantly throughout the CBM production. This requires wide technological boundaries of the main production technologies. Compared to shale gas and tight gas, deep CBM manifests different production mechanisms and relatively low free gas ratios, which lead to short flowing cycles of CBM. This necessitates timely water withdrawal for CBM production. Moreover, deep CBM wells remain in a low-production stage dominated by desorption for a long time. Based on the geological characteristics of deep coal reservoirs, this study investigated the Daning-Jixian block on the eastern margin of the Ordos Basin. It systematically analyzed the factors influencing deep CBM production, like stress sensitivity effect, velocity sensitivity, scaling blockage, Jamin effect, and free gas ratio, as well as their characteristics. Accordingly, this study pinpointed some technological challenges in deep CBM production: unknown conversion time limit between free and desorption gases, prominent corrosion and scaling caused by CO2 and water with high TDS content, and short pump inspection cycles of horizontal wells. To minimize the bottomhole pressure, boost CBM desorption, and enhance the single-well estimated ultimate recovery (EUR), this study proposed the hydraulic jet pump lifting technology, which is the most suitable for horizontal well production currently and yields the optimal economic efficiency. Moreover, this study pointed out the research directions of production and hydraulic jet pump lifting technologies for deep CBM to transition into green and intelligent gas field development, including strengthening integrated geological-engineering research, establishing efficient CBM production systems, and exploring and testing integrated rodless lifting production technology.

中国石油天然气股份有限公司攻关性应用性重大科技专项项目(2023ZZ18)

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.