Study On Low Damage Guanidine Gum Fracturing Fluid System In Yanchang Formation Deep Reservoir Of Western Yanchang Oilfield

Fracturing is an important measure to increase production of oil gas well and augmented well injection. Fracturing fluid performance is related to the fracturing construction, it can affect the stimulation effects. In this paper, guanidine gum fracturing fluid system is researched to protect the reservoir and improve the fracture flow conductivity, thereby the overall injury rate of fracturing fluid can be reduced.Based on the analysis of damage factors in Yanchang oilfield deep reservoir, such as water lock, water sensitivity and gelout residue, mainly in the efficient demulsify cleanup and residue reducing fields. As the standards of the surface/interfacial tension and demulsification effect, the commonly used surfactant and demulsifying agent are screened, through the optimization of mixture ratio, compound to obtain a breaking of emulsion cleanup additive, investigate its cleanup rate, demulsification effects, core damage properties, high efficiency demulsification cleanup effect can be achieved. Through the comparison of guanidine gum thickener water insoluble matter content, optimize thickeners, via changing crosslinking environment, crosslinking ratio to reduce guanidine gum thickener concentration, thereby residue will be lowerd.Screening of the fracturing fluid additives, and developed a low damaged guanidine gum fracturing fluid system formula which could adapt to the mesothermal high temperature, mesothermal temperature, low temperature in different formation of Yanchang oilfield, mesothermal high temperature50to70degree Celsius formula:the based fluid is0.3-0.35%HPG+l.0%KCl+0.3%PRZP+0.1%CJSJ-2+0.1%YC-JH-l+0.05%Na2CO3, cross linking agent using0.7%borax, ratio of crosslinking is100:5-100:8; mesothermal temperature35to50degree Celsius formula:the based fluid is0.25-0.3%HPG+1.0%KCl+0.3%PRZP+0.1%CJSJ-2+0.1%YC-JH-l, cross linking agent using0.7%borax+APS, ratio of crosslinking is100:5-100:8; low temperature guanidine20to35degree Celsius formula:0.2-0.25%HPG+1.0%KCl+0.3%PRZP+0.1%CJSJ-2+0.2%YC-JH-l, crosslinking agent using0.7%borax+APS, ratio of crosslinking is100:5-100:8.A comprehensive performance evaluation is taken for optimized low damage guanidine gum fracturing fluid system. The experimental results show that:optimized guanidine gun fracturing fluid system with low damage gel breaking time is about120min, after break viscosity residue content are less than260mg/L；it does not produce precipitation after mixing with formation water,has good compatibility；Three kinds of formulations in the corresponding temperature has good temperature tolerance and shearing resistance；filtration coefficient is less than2.11×10-4m／(?)m,ltration rate is low；damage on the permeability of rock matrix were lower than23％,is suitable for low permeability oil and gas reservoir fracturing.