基于煤层气高效开发的煤粉凝聚–沉降机制研究进展

Progress of coal fines agglomeration and settlement mechanism based on high efficiency coalbed methane drainage

  • 摘要: 大量低产低效井严重阻碍我国煤层气产业发展,其中,煤粉沉降导致的裂缝堵塞、管柱结块是气井稳产时间短、产气量降低甚至不产气的重要因素。系统梳理国内外煤层气井产出煤粉物质组成、生成机理、悬浮运移和产出控制等研究最新进展,总结煤粉凝聚–沉降及分散行为控制机理及关键问题,提出研究展望。煤粉问题伴随煤层气勘探开发全过程,涉及地质选区评价、工程压裂施工和排采管理控制的各个方面。煤粉包括因煤体结构破坏生成的原生煤粉和工程施工形成的次生煤粉,在气井产出中以有机碎屑和黏土矿物组成的混合物为主,部分样品黏土矿物含量高。煤粉悬浮运移受控于储层条件下煤岩结构和表面性质、nm~μm级煤粉颗粒的相互作用、有机质和黏土矿物的作用、通道内的气水流动等因素。煤粉能够适度稳定产出是排采管控的关键,涉及地层水环境对煤粉表面润湿性、表面电性和空间位阻效应的影响及作用机制,以及分散剂离子加入对煤层气的解吸和渗流能力影响等。围绕煤粉“黏附–润湿–凝聚–沉降全过程开展实验模拟”和“煤粉分散稳定性优化及流动实验”研究,以及煤粉理化性质精细表征、凝聚沉降机理分析和分散行为界定,提出适合煤粉稳定运移控制的流速,形成保持煤粉悬浮产出的基础性依据,为保障煤层气–水–煤粉稳定高效产出提供理论和技术支撑。

     

    Abstract: Significant low-yield and inefficient wells seriously hinder the development of China’s coalbed methane (CBM) industry, and the coal fractures and production pipes blocking caused by the coal fines settlement are the key influencing factors. This paper systematically investigates the latest research progress in the composition, generation mechanism, suspension transport and output control of coal fines produced by coalbed methane wells at home and abroad, summarizes the control mechanism and key issues of coal fines agglomeration-settlement and dispersion behavior, and proposes research prospects. The coal fines problem accompanies the entire process of CBM exploration and development, involving all aspects of geological selection evaluation, engineering fracturing construction, and drainage management control. The coal fines include the primary fines generated by the destruction of the coal body structure and the secondary fines formed by the engineering construction. The fines produced from the CBM wells are mainly a mixture of organic debris and clay minerals, with some samples of high clay minerals content. The suspended migration of coal fines is controlled by coal structure and surface properties, nm-μm coal particles interaction, the role of organic matter and clay minerals, and the flow of gas and water in the channel. The moderate and stable output of coal fine is the key to the management and control of drainage, involving the influences and mechanism of formation water environment on coal fines wettability, surface electrical properties and steric effects; and effect of dispersant ion addition on the desorption and seepage capacity of CBM. Focusing on “whole process experimental simulation of coal fines adhesion-wetting-agglomeration-settlement” and “optimization of coal fines dispersion stability and its moderate drainage”, accurate characterization of the physical and chemical properties of coal fines, the mechanism of agglomeration and settlement, the boundary conditions of the scattering behavior are carried out. Then the flow rate suitable for the stable migration control of coal fine is put forward to form the basic basis for maintaining the suspended production of coal fines, which provides theoretical and technical support for ensuring the stable and efficient output of methane-water-coal fines.

     

/

返回文章
返回