煤层气开发过程中煤粉产出规律与控制因素研究

The output of coal powder is one of the important factors affecting China's coalbed methane production, identification of coal powder formation mechanism and output law is the prerequisite condition and basis work for coal powder control. Based on the complexity of composition, texture and structure of coal seams in China, the southern Qinshui basin and eastern Ordos basin was selected as the research area. Aimed at weaknesses of current research of coal powder formation mechanism, in the view of the coupling effects between coal seam characters and gas development engineering disturbance, synthetically used the multi-subject theories and methods of coal petrography, coalbed methane geology, mineralogy, structure geology, coalbed methane development technology and seepage mechanics, geological background research, seam features research, test analysis, simulation experimental and numerical simulation will be unfolded. The differences of different coal petrography composition and their structural in response to environmental conditions such as pressure and fluid will be analyzed in detail to establish a scientific classification of coal powder output. Percolation characteristics of three-phase flow of gas-liquid-solid (coal powder) will be studied to reveal coal powder migration pattern in coal reservoir. And the final purpose of the project is to quantitatively identify the main control factors of coal powder output, which, in theory, can help deepen the understanding of coal reservoir evolution mechanism in coalbed methane development process, and in practice, provide the scientific basis for the reasonable control of coal powder in methane well and the protection of high yield and stable yield of coalbed methane development.

煤粉产出是影响我国煤层气排采的重要因素之一，查明煤粉成因机理和产出规律则是煤粉治理的前提条件和基础性工作。本项目从我国煤层组成、结构和构造的复杂性出发，选择沁水盆地南部和鄂尔多斯盆地东缘为研究区。针对当前煤粉机理研究的薄弱环节，从煤层自身性质与煤层气井开发工程扰动的耦合效应分析入手，运用煤岩学、煤层气地质学、矿物学、构造地质学、煤层气开发工艺学和渗流力学等多学科理论和方法，开展地质背景、煤层特征、测试分析、模拟实验和现场监测综合研究。详细剖析不同煤岩组分及其结构构造对压力、流体等环境条件的响应差异，建立煤粉产出的科学分类；研究气-液-固（煤粉）三相流渗流特征，揭示煤粉在煤储层中的运移规律；最终从定量角度查明煤粉产出的主要控制因素。上述科学问题的解决，在理论上，有助于深化认识煤层气开发过程中煤储层演变机理；在实践上，可为合理制定煤层气井煤粉控制措施、保障煤层气井高产、稳产提供科学依据。

煤层气排采过程中，煤粉滞留在裂缝中的孔道内，逐渐降低压裂形成的裂缝导流能力，使煤层气井产能过早出现衰减现象；煤粉在井内沉积，导致埋泵和卡泵，从而破坏气、水、煤粉流态的连续性，进而影响产气潜力；煤粉的动态产出已成为煤层气规模开发的瓶颈，查明煤粉成因机理和产出规律则是煤粉治理的前提和基础性工作。.本基金以鄂尔多斯盆地东缘韩城区块和临汾区块为研究区，运用煤岩学、煤层气地质学、矿物学、构造地质学、煤层气开发工艺学和渗流力学等多学科理论和方法，对煤层气开发过程中煤粉产出规律与控制因素进行了深入的研究。取得以下主要成果：（1）通过煤层与煤粉的对比研究，定量刻画韩城区块煤粉产出特征，建立了煤粉浓度与地质因素的相关模型。（2）从煤层自身特征和工程扰动及其耦合效应入手，查明了煤粉产出的控制因素，煤层的自身性质是煤粉产出的基础，而工程扰动是煤粉产出的诱因；揭示了煤粉产出规律，划分了煤粉产出的阶段。（3）综合考虑煤粉的成因机制、产出位置及其对煤层气生产的影响等因素，建立了煤粉的成因机制—产出位置综合分类系统。综合考虑煤粉成因机制、产出来源、对生产的影响等因素，提出煤粉的综合分类体系。（4）从地质、工程、设备、工艺及排采制度等方面提出了煤层气生产井煤粉管控思路体系，在韩城区块煤层气生产中取得良好应用效果。（5）在国内外期刊发表学术论文共14篇，其中，SCI收录2篇，EI收录3篇，北大中文核心8篇。出版专著1部。培养研究生10名，其中，博士2名，硕士8名。.上述工作成果，对于深化煤层气开发过程中煤储层演变机理的认识，合理制定煤层气井煤粉管控措施、保障煤层气井高产、稳产具有重要的理论和实用价值。