煤层气定量排采关键问题研究

For the key problems in the quantitative production of coalbed methane, such as the dynamic variation rules of reservoir parameters, gas-water inflow performance relationship and pressure propagation are mainly qualitative which are not directly associated with the parameters of actual production and not characterized quantitatively, the phenomena of reservoir damage and gas channel blocked by pulverized coal are serious and the workovers of pump inspection caused by pulverized coal are frequent, in this project the inflow performance relationship model in different production stages of CBM well will be established for analyzing the dynamic law of gas-water inflow and the variation of production capacity. Considering the connections among the IPR, the pressure propagation, the variation of production capacity and the model of permeability in CBM well, the dynamical prediction model and the mathematical model of coal reservoir damage based on the production data of CBM well will be established for analyzing the dynamic influence of actual production parameters on coal reservoir parameters and structural damage. Through the theoretical study and experimental analysis, the migration law of pulverized coal in the gas channel and the wellhole is researched. Finally, the fuzzy comprehensive evaluation system under the conditions of various factors will be established for the quantitative and optimal design of production parameters, and the quantitative drainage and production method based on the conditions of the reservoir protection and the appropriate discharge of pulverized coal will be obtained. The above research has the important theoretical basis and practical significance for increasing the gas output of CBM well and promoting the development of CBM industry in China.

针对煤层气定量排采过程存在的储层性质、气水流入动态、压力传播特征的动态变化规律多为定性，缺乏与现场排采参数的直接关联及定量化表征，储层伤害和煤粉堵塞产气通道现象严重，煤粉造成的检泵修井频繁等系列关键问题，本项目拟通过建立煤层气井不同排采阶段下的流入动态模型，分析气水流入动态规律和产能变化；综合考虑煤层气井流入动态、压降传播规律、产能变化模型及渗透率模型之间的联系，建立基于排采数据的储层渗透率动态预测模型和储层伤害数学模型，分析实际排采数据对煤储层参数和结构破坏的动态影响，得到储层保护的定量化条件；从储层产气通道和井筒两方面对煤粉运移规律进行理论和实验研究，得到煤粉适度排出的定量化条件；最终建立多因素下补偿模糊综合评价体系，对排采参数进行定量优化设计，形成基于储层保护、煤粉排出及产量稳步提升的定量化排采方法。该研究对于提高煤层气井产气量与促进我国煤层气产业发展具有很好的理论和实践意义。

针对煤层气定量排采过程存在的储层性质、气水流入动态、压力传播特征的动态变化规律多为定性，缺乏与现场排采参数的直接关联及定量化表征，储层伤害和煤粉堵塞产气通道现象严重，煤粉造成的检泵修井频繁等系列关键问题，本项目通过建立煤层气井不同排采阶段下的流入动态模型，分析了气水流入动态规律和产能变化；综合考虑煤层气井流入动态、压降传播规律、产能变化模型及渗透率模型之间的联系，建立了基于排采数据的储层渗透率动态预测模型和储层伤害数学模型，分析了实际排采数据对煤储层参数和结构破坏的动态影响，得到了储层保护的定量化条件；从储层产气通道和井筒两方面对煤粉运移规律进行理论和实验研究，得到了煤粉适度排出的定量化条件；最终对排采参数进行定量优化设计，形成了基于储层保护、煤粉排出及产量稳步提升的定量化排采方法。该研究对于提高煤层气井产气量与促进我国煤层气产业发展具有很好的理论和实践意义。