The Model Of Thermal Storage Recharge Capacity For Sandstone Pore In Tianjin

There is a unique geographical location and has high quality and huge reserves of deep pore geothermal resources under the sedimentary basins in Tianjin.However,as a carrier of geothermal fluid is not inexhaustible,endless use.Continuous and excessive exploitation will lead to a series of geological and environmental problems,such as the decline of thermal storage pressure.Recharge is one of the main methods to realize the development and protection of geothermal resources,which is mainly manifested in the following three aspects:(1)it can reduce the burden of geothermal fluid discharge on municipal sewage pipe network,and cause thermal and chemical pollution to the environment;(2)maintaining regional reservoir pressure.It is the most direct and effective way of supply except natural supply;(3)Sustainable development and utilization.It can increase the ability to extract heat from thermal reservoir and truly reflect the clean and renewable characteristics of geothermal resources.In this paper,Neogene pore sandstone in Tianjin is selected as the research object,and the sedimentary characteristics are analyzed.It is found that the Neogene pore sandstone is a set of fluvial deposits,the lithology is mainly sandstone mudstone,and has the same source area.During the Guantao sedimentary period,alluvial fan-distinguishing river deposits were developed in the part of Yanshan Piedmont alluvial plain,and in the south,far from the influence range of Yanshan provenance.It was a low bend river deposit.During the sedimentary period of Minghua formation,the regional tectonic activity is relatively weakened.The topography is more smooth,and the lateral migration and deposition of meandering sand dam is obvious.Through the collection and analysis of a large number of existing recharge test data,the distribution of recharge capacity in the study area is obtained.The thermal storage and recharge capacity of Minghua Town Group is generally not good,and the thermal storage recharge capacity is less than 30m~3/h.The thermal storage recharge capacity of Guantao formation in Beitang sag is the best.The thermal storage recharge capacity is above 80 m~3/h.The recharge capacity of Guantao formation in the north of Dacheng uplift and Banqiao sag is similar and good.The recharge capacity is 60~80 m~3/h.The thermal storage and recharge capacity of Guantao formation in Wuqing depression is relatively poor,The average irrigation amount of the experiment is 66 m~3/h.Considering the sedimentary characteristics and recharge capacity distribution of Neogene pore sandstone,the target core is tested,compared and analyzed.Considering the mutual influence factors between the physical parameters of thermal storage,the evaluation model of thermal storage of pore sandstone is established.The recharge capacity of Neogene pore sandstone in Tianjin is evaluated by using this model.The evaluation results show that the recharge capacity of pore sandstone is mainly reflected by permeability,which is affected by shale content and porosity.The comprehensive influence of specific surface area and other parameters.Generally speaking,when the shale content of pore sandstone thermal reservoir is less than 15%,the larger the particle size is,the larger the formed pore channel is,and the higher the effective porosity is.If the dry density is more than 1.7 and the sandstone has good cement property,the better recharge capacity of the reservoir is got.