煤储层氧化增渗作用机理及应用  

Oxidant stimulation to enhance coal seam permeability mechanism and application

作　　者：荆振华 潘松圻[1] 王小明[3] 袁铭 李勇[4] 刘恩涛[3] 刘翰林 UNDERSCHULTZ Jim STEEL Karen JING Zhenhua;PAN Songqi;WANG Xiaoming;YUAN Ming;LI Yong;LIU Entao;LIU Hanlin;UNDERSCHULTZ Jim;STEEL Karen(Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;School of Chemical Engineering,The University of Queensland,St Lucia Qld 4072,Australia;School of Earth Resource,China University of Geosciences(Wuhan),Wuhan 430074,China;College of Geosciences and Surveying Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]昆士兰大学化工学院,圣卢西亚4072 [3]中国地质大学(武汉)资源学院,湖北武汉430074 [4]中国矿业大学(北京)地球科学与测绘工程学院,北京100083

出　　处：《煤炭学报》2022年第11期3975-3989,共15页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(42102167);中国博士后科学基金面上资助项目(2020M680240)。

摘　　要：氧化法提高煤储层渗透率(氧化增渗)是指利用氧化反应溶解煤层割理周围有机质,增加割理宽度,提高煤储层渗流能力的一种煤层气增产方法。选择澳大利亚Bowen盆地煤样为研究对象,针对不同煤样大小,利用多种自主组装实验及孔裂隙、渗透率、CT扫描等测试手段,系统阐述氧化增渗的作用机理及应用前景。研究结果显示:煤基质在多种氧化剂中存在不同程度的溶解、膨胀和破裂现象,对比多种工业常用氧化剂对煤样的氧化效果,认为次氯酸钠(NaClO)氧化能力较强,可有效提高样品孔隙度,增加裂隙宽度。岩心驱替实验证明氧化法主要提高煤储层水平方向渗透率,微米CT扫描对比驱替前后岩心图像发现NaClO可刻蚀割理表面,在扩大割理宽度的同时在煤基质中产生新的孔裂隙。煤中矿物与氧化剂无明显反应,盐酸去除矿物的煤样氧化反应显示煤中渗流通道宽度增加,但是覆压条件下渗透率下降,显示矿物在围压条件下发挥支撑作用,保证煤体结构完整性。同一煤样不同煤岩组分的氧化反应强度差异主要受其孔裂隙差异性控制,与煤分子结构相关性较小。上述研究证明:氧化法提高煤储层渗透率,作为一种新型储层改造技术,有助于丰富煤储层改造手段,提高煤层气采收率,同时补充煤氧化机理的理论认识,推动煤层气产业发展。The oxidant stimulation of coal seams aims to dissolve the coal organic matrix around the coal cleats by solvent oxidation for widening the cleat aperture and thus enhance coal seam permeability.The coal samples were collected from Bowen Basin,Australia,and examined with multiple techniques mainly including the pore measurement,permeability test,and computed tomography(CT)scanning to systematically elucidate the oxidant stimulation mechanisms and application prospect.The results reveal that the coal particles demonstrate dissolution,swelling,and breakage to a variable extent in different oxidants.Among them,Sodium Hypochlorite(NaClO)appears to show the most extensive oxidation that can effectively increase the coal porosity and enhance the artificial coal cleat aperture.The core flooding test approves the permeability enhancement after the oxidant flows through,especially the horizontal permeability,which is then elucidated by the micro-CT scanning showing that the NaClO can etch the coal cleat and meanwhile generate new pores and fractures after oxidation.The minerals deposited in the cleats have a negligible reaction with oxidants,but when they are removed by hydrochloric acid(HCl),the permeability after oxidation declines under confining pressure,although the oxidant can still increase the cleat aperture.This means the pristine minerals can perform as the proppants to maintain the integrity of the coal structures.The different lithotype coals separated from the same coal core exhibit different oxidation effects which are proposed to be controlled by their different pore structures rather than the differences in their molecular structures.Overall,the results in this study appear to illustrate that the oxidant stimulation as an alternative of the traditional coal seam stimulating methods can benefit the coal permeability and be conductive to the theory development with respect to coal oxidation from the level of coal molecular structures.

关 键 词：渗透率 氧化法 煤储层 次氯酸钠 有机质分子结构 孔隙结构 

分 类 号：P618.11[天文地球—矿床学]