College of Geosciences, China University of Petroleum (Beijing)
National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing)

渤海湾盆地的大地热流高，5 000 m埋深地层平均温度为175℃，热储岩性以低孔低渗的变质岩、火成岩为主，具备形成干热岩资源的条件。基于大地热流、岩石热导率、生热率等热参数，利用COMSOL软件建立三维水热耦合的干热岩开采模型、分析不同井间距、注采速率、布井方式等差异开采方案下在100 a内对热储层温度的影响随开发时间的变化，选取最优方案并估算干热岩资源。结果表明：注采速率一定时，随着开采时间的增加，开采井水温度下降速率与井间距成反比；当注采井间距一定时，注采速率越大，开采井水温度下降越快，发生“热突破”的时间越早；其他条件相同的情况下，“两采两注”布井方案比“一采一注”布井方案获得的热量更多，开采效率更高。基于上述认识，确定研究区最优开采方案为：年限50 a、井间距400 m、注采量90 m3/h、“两采两注”方式。此方案下，可获得开采井水平均温度为172℃，对应全渤海湾盆地可采资源量为3.28×1019 J/a。以河北任丘市为例，按照民用住宅热负荷指标100 W/m2计算，利用最优方案进行干热岩的开采，仅需157.75 km2干热岩有利区即可满足全市居民供暖需求。因此，开发利用研究区干热岩资源，可增强华北地区能源供应保障能力，打造可持续发展的绿色低碳能源体系。

The Bohai Bay Basin, characterized by high terrestrial heat flow, formation temperatures average of 175℃ at a depth of 5000 m, and reservoirs with lithologies dominated by low-porosity and low-permeability metamorphic and igneous rocks, meets the requirements for the formation of hot dry rock (HDR) resources. Based on geothermal parameters such as terrestrial heat flow, rock thermal conductivity, and heat production rate, this study established a three-dimensional HDR exploitation model with thermo-hydro coupling using the COMSOL software. Furthermore, this study analyzed the effects of spacing between production and reinjection wells, reinjection and production rates, and well arrangement mode on the temperature evolution of the geothermal reservoir with exploitation time within 100 a. Accordingly, it selected the optimal scheme and estimated the potential HDR resources. Key findings are as follows: (1) Under certain reinjection and production rates, the rate of decline in production well water temperature over time is inversely proportional to injection and exploitation well spacing. (2) Under a certain well spacing, higher reinjection and production rates were associated with a quicker decrease in the water temperature of production wells and earlier thermal breakthroughs. (3) Regarding well arrangement mode, the HDR exploitation using two production wells and two reinjection wells yielded more heat and higher efficiency than that using one production well and one reinjection well providing other conditions remained unchanged. Based on these results, the optimal HDR exploitation scheme was determined, consisting of an exploitation duration of 50 a, a well spacing of 400 m, reinjection and production rates of 90 m3/h, and well arrangement mode comprising two production wells and two reinjection wells. Using this scheme, the average water temperature of the production wells will be 172℃, corresponding to total recoverable resources of 3.28×1019 J/a of the entire Bohai Bay Basin. For instance, in Renqiu City of Hebei Province, which falls within the delineated HDR favorable area, the heating demands of the entire city can be met using merely 157.75 km2 of HDR favorable area if the optimal HDR exploitation scheme is adopted, as calculated based on a heat load index of residential buildings of 100 W/m2. Therefore, the exploitation and utilization of HDR resources in the study area can enhance the energy supply and guarantee capabilities of North China, contributing to the creation of a sustainable, green, and low-carbon energy system.

国家自然科学基金面上项目(42172334)；国家重点研发计划课题(2021YFA0716003)

江晓雪，朱传庆，丁蕊，等. 渤海湾盆地干热岩开发利用前景评估−基于开采优化数值模拟的认识[J]. 煤田地质与勘探，2024，52(1)：93−103.

JIANG Xiaoxue，ZHU Chuanqing，DING Rui，et al. Evaluating the exploitation and utilization prospects of hot dry rock in Bohai Bay Basin: Understanding based on numerical simulations for exploitation optimization[J]. Coal Geology & Exploration，2024，52(1)：93−103.