Preparation Of Fracturing Proppant From Waste Drilling Mud And Study Of The Mechanism Of Sintering Process

In recent years,the continuous development of petroleum industry in China has provided a stable supply for industrial production and energy demand of national life.As the most representative production waste of oil and gas extraction,waste drilling mud,with its large pollution ratio,complex composition and obvious direct environmental impact,was in urgent need of an effective resource-based disposal method to further aggravate and exacerbate this problem.According to the nature of waste drilling mud,using it as raw material to prepare fracturing proppant required in the oil well fracturing process was an innovative study of resourceful disposal of solid waste,and the recycling of fracturing proppant in the oil and gas extraction process was fully in line with the concept of sustainable development promoted in China.In this study,we first analyzed the plasticity index,thermal properties,and elemental and mineral composition performance indexes of oil well waste gas mud and other related raw materials,and explored the mechanisms by which the ratios of various raw materials,sintering temperatures and manganese ore powder additions affect the strength performance of the prepared fracturing proppant,and further expanded the discussion on the mechanism of using red mud,a waste material,to achieve the light weighting performance of the proppant,and finally combined with the thermodynamic Finally,the sintering process of the fracturing proppant was analyzed computationally by combining thermodynamics,and a thermodynamic model of the proppant sintering process was realized.The main findings of the study are shown below.Firstly,the waste drilling mud has the basic requirements needed for fracture proppant sintering raw materials: it and bauxite have plasticity indexes of 10.5 and 11.6respectively,which meet the requirements of ceramic pellet forming;through TGDTG/DSC test analysis,the waste drilling mud obtained about 17% weight loss when heated to 1400°C due to volatilization of organic matter and decomposition of salts,while bauxite exhibited strong thermal stability with little change in weight.Both waste drilling mud and bauxite were composed of Al,Si and O as the main elements and contained more alkali/alkaline-earth metal oxides,which had the basic composition of fracture proppant sintering raw materials.Secondly,the optimal preparation of fracturing proppant was clarified: by changing the raw material ratio,sintering temperature and manganese ore powder addition,the correlation law between different experimental conditions and sample strength was analyzed based on the test results of bulk density,apparent density,crushing rate,ultimate compressive strength,hardness,XRD and microscopic morphology of the samples.Secondly,the optimal preparation of fracturing proppant was clarified: by changing the raw material ratio,sintering temperature and manganese ore powder addition,the correlation law between different experimental conditions and sample strength was analyzed based on the test results of bulk density,apparent density,crushing rate,ultimate compressive strength,hardness,XRD and microscopic morphology of the samples.In particular,at the sintering temperature of 1300 ?,when the A/S ratio was 3/1,a sample with a crushing rate of 11.35% at 52 MPa pressure was obtained;when the A/S ratio was maintained at 3/1,increasing the sintering temperature could continuously improve the proppant strength,and the crushing rate was reduced to 5.13% at 1350 ?;with an A/S ratio of 3/1 and a sintering temperature of 1300°C,the addition of 5 wt% manganese ore powder increased the strength of the fracturing proppant by 6.24% while reducing the sintering temperature requirement by 50°C.Thirdly,the pathway and mode of action of the lightening process with red mud as proppant were revealed: the pathway of action of the proppant lightening process was systematically analyzed by examining the properties of the samples with different red mud additions,and it was demonstrated that the changes in physical properties were caused by the confrontation between the glaze tension on the proppant surface and the internal gas expansion force,but the changes in the lightening properties caused by the increase of the silica content in the system due to the continuous addition of red mud could not be ignored.Finally,a thermal treatment model for the sintering process of fracturing proppant with waste drilling mud was constructed: systematic TG-DTG/DSC thermal analysis tests were conducted on the fracturing proppant raw material,and the reaction types of the four thermal reaction stages were demonstrated by the changes in both weight and energy dimensions during the sintering reaction;the thermodynamic three-element parameters of the three stages of the reaction,except the first stage dominated by the evaporation reaction of water,were calculated using the KAS method and the Starink method,and the thermodynamic modeling of the above stages of the reaction process was successfully constructed using the SSRA and DAEM methods to reveal the thermodynamic mechanism of the sintering process,which provided a great reference value for optimizing the operating conditions of the solid-phase sintering reaction.