Research and Application of Integrated Variable Viscosity Fracturing Fluid for Deep Coal Seams in the Eastern Edge of the Ordos Basin
A set of integrated variable viscosity fracturing fluid system has been developed in combination with the requirements of large-scale fracturing development process for deep coal seams.The fracturing fluid system is composed of lotion thickener,multi-functional additives,etc.Low viscosity-medium viscosity-high viscosity slick water system can be obtained in real time by adjusting the concentration of the lotion thickener.Experimental tests have shown that the fracturing fluid system exhibits excellent performance in terms of instant dissolution,viscosity increasing,resistance reduction,and shear resistance:the instant dissolution time can be 20-30 seconds;the apparent viscosity remains basically unchanged at variable shear rate of 1 s-1→ 1 000 s-1→1 s-1;the drag reduction rate does not change significantly and is greater than 70％under flow shear conditions.In addition,the system has a lower surface tension and better anti swelling performance,which is manifested as a lower core damage rate to coal and rock.Combined with volume transformation fracturing technology,it has been applied on a large scale in the deep coal seam fracturing development of the Ordos Basin,with good production increase effects.
deep coal seamlotion thickenervariable viscosity fracturing fluidshear resistanceresistance reduction
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