Study On High Salinity And High Density Fracturing Fluid

In recent years,fracturing technology has become an effective stimulation technology in the development of unconventional oil and gas resources.The high-temperature and high-pressure formation environment and dense matrix put forward higher requirements on the fracturing fluid.In order to effectively reduce the cost of fracturing operations,this paper aims to study a set of high specific gravity and high salinity fracturing suitable for ultra-deep wells in Xinjiang based on the effective use of oilfield produced water,sewage,high salinity well water and salt lake water.In terms of the selection of a single agent for fracturing fluid,a thickener with a small residue content-modified hydroxypropyl super guar gum JK101 with a low residue content is selected through the insoluble content test.Based on the idea that borate and organic ligand form a stable organic complex under the action of chemical additives,this paper has developed a crosslinking agent with good picking performance under alkaline conditions—YZ-1;Considering that the calcium and magnesium ions in the formation water have a significant effect on the swelling effect of the thickener and cannot be effectively cross-linked,for this problem,a chelating agent that satisfies300,000 mineralization formation water,CA-5,is further selected The relationship curve between the amount of chelating agent 50%CA-5 and the total concentration of Ca²⁺and Mg²⁺was explored to provide a theoretical basis for the on-site fracturing fluid preparation;In order to meet the requirements of ultra-deep wells and reduce the injection pressure of construction pumps,an organic compound formate weighting agent-JZ-1 was compounded in the laboratory,and its saturated solution density can reach 1.36g/cm³.Based on the selection of single agent,two formulas of fracturing fluid were determined:(1)High salinity fracturing fluid system1%CA-5(50%)+0.35%JK101+0.55%YC-150+0.55%YZ-1;(2)High specific gravity and high salinity fracturing fluid system35%JZ-1+1%CA-5(50%)+0.35%JK101+0.55%YC-150+0.55%YZ-1.Both system(1)and system(2)have good pick-up performance and salt resistance,which can meet the basic performance requirements of the fracturing fluid system.In view of the above two fracturing fluid systems,this paper carried out the performance testing of fracturing fluid base fluid,temperature resistance performance test,gel breaking performance test,fracturing fluid residue content test and core damage test on high salinity fracturing fluid system.Comprehensive performance evaluation with high specific gravity and high salinity fracturing fluid system.The results of the study show that the shearing viscosity of the fracturing fluid is always above 50mPa·s at 150? and 170s-1 shear for 90min.The compatibility of each additive is good.The average damage rate of the core is 19.83% and 20.86% respectively;the drag reduction rate is 72.02% and 73.46%,respectively,to meet the needs of on-site construction.