Research On The Preparation And Properties Of Proppants Of Clearwater Fracturing For Coalbed Methane Wells

As a high-quality clean energy in the new era,the exploitation and utilization of coalbed methane can not only make up for the shortage of conventional natural gas and other resources,but also reduce the occurrence of gas explosion and other accidents in coal mining.The national and local governments have issued numerous policies to promote the exploitation and utilization of coalbed methane.In response to the policies,most enterprises have carried out research and development of coalbed methane exploitation and production enhancement technologies.Nowadays,hydraulic fracturing technology is the main technology to increase coalbed methane production.At present,in order to reduce the damage of fracturing fluid on coal matrix,clean water or slick water fracturing system is often used,and the proppants matching with it has become the key of research.By comparing the existing proppants,it is found that the strength of ultralow density ceramic proppants is higher than that of natural quartz sand,and the preparation process is simpler than that of resin-coated proppants,but the sintering temperature is higher(> 1250 ℃)and the firing temperature range is narrower(20 ℃).Therefore,the purpose of this study is to explore the preparation of ultra-low density ceramic proppants with lower sintering temperature(<1250 ℃)and wider firing temperature range(≥ 40 ℃)and realize industrialization.The main research conclusions are as follows:(1)Based on the characteristics that coal gangue can broaden the firing temperature range of materials and reduce the sintering temperature to a certain extent,in this paper,coal gangue is used to widen the firing temperature range and reduce the sintering temperature of ceramic proppant,and the influence of coal gangue addition amount on its performance is studied.The research shows that after adding coal gangue,the firing temperature range of ceramic proppants is significantly widened,the widest can reach 80 ℃.When the content of coal gangue increases,the density can be reduced,but the crushing rate increases.When the content of coal gangue is greater than or equal to 20 wt.%,a large number of pores will be formed,resulting in a large increase in the crushing rate.Therefore,appropriate content of coal gangue should be selected to improve the performance of ceramic proppant(2)Based on the characteristics that pretreatment(calcined)coal gangue can improve the material strength,in this paper,pretreatment coal gangue is used to improve the strength of ceramide proppant and the influence of pretreatment coal gangue addition amount on its performance is studied.The research shows that the strength of ceramic proppants is significantly improved after the addition of pretreated coal gangue(breakage rate can meet the domestic industry standard of9% under 42 MPa closure pressure).When the amount of pretreatment coal gangue is increased,the density decreases,but the crushing rate increases,and the firing temperature range does not change(40 ℃).When the amount of pretreatment coal gangue is greater than or equal to 25 wt.%,within the firing temperature range,the crushing rate cannot meet the domestic industry standard(9%),but can meet the international standard(10%),which provides a reference value for the actual production.(3)Conduct pilot test on the research results and apply them to field production test Wells to analyze the gas production effects of 1 test well and 5contrast Wells on the same platform.The results showed that the gas production from the test well was twice as high as the most productive gas production of the five comparison Wells and five times as high as the average gas production of the five comparison Wells.