次氯酸钠水溶液对煤储层裂隙的增透作用机制研究

So far, the hydraulic fracturing measure of improving coal reservoir permeability is mainly through physical way, and there is less research on hydraulic fracturing measure of improving coal reservoir permeability by chemical action. Recent studies suggest that coal macromolecular structure can be damaged in different degree by sodium hypochlorite solution under mild conditions, making coal dissolved in antioxidant solution. Therefore, it is possible improving permeability of coal reservoir fracture by the physical and chemical actions of sodium hypochlorite solution. .In order to determine the mechanism on improving permeability of coal reservoir fracture by sodium hypochlorite solution, we will research the features of oxidation depolymerization under different conditions; we set up the physical models of coal reservoir fracture，determining coal reservoir permeability and analyzing the effect of improving coal reservoir permeability. We research the regularity of sodium hypochlorite solution migration along fracture and on both sides of the fracture, and determine the characteristics of the fracture and gas migration along fracture.At last, we will set up the mathematical models,and find out the mechanism of improving permeability of coal reservoir fracture by sodium hypochlorite solution, which is used as theoretical and experimental basis on improving permeability of coal reservoir fracture by sodium hypochlorite solution.

煤储层水力压裂增透措施目前主要是通过物理作用来提高煤储层渗透性。现有研究表明，次氯酸钠水溶液可在温和条件下与煤发生氧化解聚反应，使煤溶解于水溶液中。因此，次氯酸钠水溶液用于煤储层水力压裂，有望将水力压裂的物理作用与化学作用结合起来，通过次氯酸钠对煤储层裂隙的氧化解聚作用进一步提高水力压裂对煤储层的增透效果。.为探明次氯酸钠水溶液对煤储层裂隙增透的物理化学作用机制，拟研究不同条件下次氯酸钠水溶液对煤的氧化解聚规律；建立煤储层裂隙物理模型，测定次氯酸钠水溶液作用前后的裂隙渗透性，分析次氯酸钠水溶液对裂隙的增透效果；研究次氯酸钠水溶液在煤储层裂隙及裂隙两侧煤壁运移规律，测定次氯酸钠水溶液作用后煤储层裂隙改性特征和瓦斯在裂隙中的运移特性，建立次氯酸钠水溶液对煤储层裂隙增透的数学模型，研究次氯酸钠水溶液对煤储层裂隙增透的物理化学作用机制，为次氯酸钠水溶液用于煤储层水力压裂增透奠定理论和实验基础。

渗透率是矿井瓦斯抽采中关键参数，渗透率越大越有利于瓦斯抽采、有利于矿井安全生产，但是我国大部分矿区呈低渗透性，实现规模化和产业化开发难度大，随着开采深度加大，地应力和瓦斯压力进一步增加，井下抽采难度增大。如何有效提高煤储层的透气性成为煤层气开发和预抽煤层瓦斯的关键问题。项目通过次氯酸钠水溶液对煤样的氧化解聚来研究次氯酸钠水溶液对煤的增透作用。利用晋城无烟煤的煤样、裂隙物理模型和现场煤层的渗透率测定实验来研究次氯酸钠水溶液对煤样的增透作用，得出了主要相关结论：次氯酸钠水溶液对煤的氧化率随时间的增加而增加；次氯酸钠溶液浓度在6%左右时为较适宜的反应浓度；随着pH值的增加氧化率逐步下降，次氯酸钠水溶液氧化效果较好的pH值为9；反应时间越长煤样的渗透率增加的越多；次氯酸钠水溶液的浓度为2%到10%之间变化时，次氯酸钠水溶液的浓度为6%时对煤样的增透效果最好；当含水率较小时，次氯酸钠水溶液能对煤储层起到较好的增透效果。