School of Energy Resources, China University of Geosciences(Beijing)
Coal Reservoir Laboratory of National Engineering Research Center of Coalbed Methane Development & Utilization
Petrochina Coalbed Methane Company Limited

准确量化储层压力的实时变化是预测储层孔渗变化特征、控制采气效果的关键因素。为了进一步探究保德地区煤储层压力动态变化特征及其对煤层气井产能的影响，在考虑正负效应的影响下，基于生产动态资料，建立了煤储层压力实时模拟检测技术，定量刻画了保德地区饱和煤层气藏和欠饱和煤层气藏煤储层压力动态变化规律。通过对比不同压降条件下的产能，为生产提供预测依据和理论指导。在煤层气井开发过程中，饱和煤层气藏平均储层压力呈线性下降，以单井平均日产气量为选定标准，压降速率分为快速降落型(大于0.096 MPa/m)、适稳降落型(0.063～0.096 MPa/m)和缓慢降落型(小于0.063 MPa/m)，适稳降落型(4648 m3/d)压降制度煤层气井产能明显好于快速降落型(2531 m3/d)和缓慢降落型(2968 m3/d)，快速降落型煤层气井产能最低。欠饱和煤层气藏在开发初期单相水流阶段，平均储层压力急速下降，初期压降速率分为快速降落型（大于0.38 MPa/m）、适稳降落型（0.228～0.38 MPa/m）和缓慢降落型（小于0.228 MPa/m），快速降落型（526 m3/d）压降制度煤层气井产能明显低于适稳降落型（1021 m3/d）和缓慢降落型（1054 m3/d）；随着储层压力降到临界解吸压力后，为气、水两相流阶段，储层压力呈线性缓慢下降。建议保德地区饱和煤层气藏初期压降速率维持在0.063～0.096 MPa/m，欠饱和煤层气藏初期压降速率不超过0.38 MPa/m。

Accurately quantifying the real-time variation of reservoir pressure is the key factor to predict the variation characteristics of reservoir porosity and permeability and control the gas recovery effect. In order to further explore the characteristics of coal reservoir pressure dynamic variation in Baode area and its impact on the productivity of coalbed methane (CBM) wells, based on production dynamic data, a real-time simulation and detection technology of coal reservoir pressure was established while quantitatively described the pressure dynamics of saturated and unsaturated CBM reservoirs in Baode area, by considering the influence of positive and negative effects. By comparing the productivity under different pressure drop conditions, the prediction basis and theoretical guidance were provided for production. During the exploitation of CBM wells, the average reservoir pressure of saturated CBM reservoirs decreases linearly. Taking the average daily gas production of a single well as the selected standard, the pressure drop rate is divided into three types: fast falling type (more than 0.096 MPa/m), steady falling type (0.063~0.096 MPa/m) and slow falling type (less than 0.063 MPa/m). The productivity of CBM wells with steady-descent type (4648 m3/d) pressure drop system is significantly better than that of fast-descent type (2531 m3/d) and slow-descent type (2968 m3/d). Fast-descent type CBM wells have the lowest productivity. In the single-phase water flow stage of the undersaturated coalbed methane reservoir in the early stage of development, the average reservoir pressure drops rapidly, and the pressure drop rate is divided into three types: fast falling type (more than 0.38 MPa/m), steady falling type (0.228—0.38 MPa/m) and slow falling type (less than 0.228 MPa/m). The productivity of CBM wells with fast-descent type (526 m3/d) pressure drop system is significantly lower than that of steady-descent type (1021 m3/d) and slow-descent type (1054 m3/d). As the reservoir pressure drops to the critical desorption pressure, the reservoir pressure decreases linearly and slowly in the gas-water two-phase flow stage. It is suggested that the initial pressure drop rate of saturated CBM reservoirs should be maintained at 0.063~0.096MPa/m, and the initial pressure drop rate of unsaturated CBM reservoirs should not exceed 0.38 MPa/m in Baode area.

国家自然科学基金资助项目（42172188）

宗　鹏，侯　伟，许　浩，等. 煤储层压力变化规律模拟研究[J]. 煤炭科学技术，2023，51（8）：169−177

ZONG Peng，HOU Wei，XU Hao，et al. Simulation research of coal reservoir pressure variation law[J]. Coal Science and Technology，2023，51（8）：169−177