Study On Rheology And Pulse-carrying Performance Of Fiber Fracturing Fluid

Pulsing fiber-sand hydraulic fracturing technology is for making sand-group discontinuous supporting come true via pulsed injection of sand-carrying fracturing fluid and fracturing fluid mixed with fiber in the fracture. Fiber added in the fracturing fluid can improve the proppant-carrying capacity. The proppant-carrying capacity is closely related to the rheological properties of fiber fracturing fluid. However, there are few researches on the rheological properties and carrier property of fiber fracturing fluid at home and abroad currently. In this paper, researches of fiber fracturing fluid rheological property and carrier performance will be carried out, the relationships of each other will also be delved.By means of widely researching the fiber suspension system's rheological properties research method, this article uses Haake Mars ? rheometer coaxial cylinder sensor system carry out viscous shear experiment for fiber fracturing fluid linear glue's viscosity characteristics and uses plate-plate sensor test system carry out frequency scanning experiments for fracturing fluid gel's viscoelastic characteristics respectively. At the same time, this article will analyze the influence law of fracturing fluid rheological property caused by fiber. Then, we carry out the dynamic pulse carrier physical model experiment and sand-group static sedimentation experiment for fiber fracturing fluid gel to analyze the influence of fracturing fluid carrier performance caused by fiber. At last, this article will combine fiber fracturing fluid gel rheological parameters with sand-group settling velocity to discuss the correlation of each other. Meantime, we will realize how the sand-group settling velocity change with fiber fracturing fluid rheological parameters and understand the mechanism of fiber to increase the carrying capacity of fracturing fluid. The main research results are as follows:(1) Fiber fracturing fluid linear glue system viscosity increases with growth of fiber mass concentration and length to diameter ratio; fiber fracturing fluid gel storage modulus and loss modulus increases with growth of fiber mass concentration and length to diameter ratio. The increase of storage modulus is equal to the increase of the fracturing fluid's ability to overcome the deformation. The increase of loss modulus is equal to the increase of the system viscosity, which can enhance the viscous resistance. Therefore, the enhancements of viscoelasticity will improve proppant-carrying capacity of fiber fracturing fluid.(2) Fiber fracturing fluid gel's dynamic pulse carrier experiments show the feasibility of pulse fracturing technology. After stopping the pump, the settlement process of proppants show that proppants gather into cluster and settle as a whole. At the same time, sand-group's settlement is not beneficial to keeping fracture vertical high conductivity channel. Fiber fracturing fluid gel's static carrier experiments show that fiber added in the sand-carrying fluid plays an important role in keeping the overall integrity of sand-group carrying fluid, fiber added in the fracturing fluid mainly helps to reduce the settling velocity of sand-groups. At the same time, the effect of increasing HPG guar gum concentration to reduce the settling velocity of sand-groups is more apparent than the effect of increasing fiber concentration or length to diameter ratio, which shows that the fiber added in the fracturing fluid mainly plays a role in auxiliarily reducing the settling velocity of sand-groups.(3) Correlation study combining fiber fracturing fluid gel rheological property with sand carrier shows that fiber added in fracturing fluid gel can decrease sand-groups settling velocity remarkably when HPG guar concentration is 0.25 or 0.35 percent, fiber added in fracturing fluid gel can only reduce sand group settling velocity gently when HPG guar concentration is 0.45 or 0.55 percent. Curve fitted by settling velocity and rheological property shows that settling velocity decreases in power function relationship with viscoelastic enhancement. The calculation shows that the storage modulus of 2.84 and the loss modulus of 0.8Pa under oscillating angular frequency of lrad/s can be chosen as the critical reference value for flat drop of sand group settling velocity in fiber fracturing fluid.Based on the study of fiber fracturing fluid rheological property, pulsing carrier and their correlation, the influence rule of the fiber to fracturing fluid rheological property and carrier can be got, which can provide reference for on-site pulsing fiber-sand fracturing construction.