Performance Evaluation of the Multifunctional Variable-Viscosity Slick Water for Fracturing in Unconventional Reservoirs

Abstract

The traditional guar gum fracturing fluid system has the drawbacks of the fracturing process of unconventional oil and gas deposits, such as high drag resistance and large residuum harm, which is gradually replaced by the system of the slick water fracturing fluid. The conventional slick water system, however, still has the features of low sand-carrying capability. Therefore, high-viscosity slick water is often used in fracturing operations, but most of the high-viscosity slick water is difficult to prepare, dissolve, and break gels, which needs to be improved. Based on the abovementioned problems, a new type of multifunctional variable-viscosity slick water is proposed in this paper. The self-made loop drag test unit, a dynamic crack sand-carrying model, a multifunctional core flow device, and other equipment were used for testing, and a set of systematic evaluation methods for the performance of multifunctional variable-viscosity slick water are established. In addition, the mechanism of improving sand-carrying capacity and increasing viscosity and solubilization was explained through the macroevaluation experiment of polymer properties and the analysis of the polymer microstructure. The experimental results show that compared with high-viscosity slick water, the multifunctional variable-viscosity slick water has good drag-reducing performance, the drag-reducing rate can reach more than 75%; the intersection value of viscoelastic modulus is about 0.01 Hz, the sand carrying capacity is higher; the gel-breaking time is faster, the residue content is lower, 38.5 ppm; it has the characteristics of low harm, the harm rate to the core is 18.30%; and it also has the performance of enhancing oil recovery.

Comparative Studies on Thickeners as Hydraulic Fracturing Fluids: Suspension versus Powder

“…This is due to the small particle size and large specific surface area of the nano-silica, which possessed silanol groups on the surface of the silica particles. These silanol groups relied on interaction to form hydrogen bonds, forming a three-dimensional network structure that could enhance the viscosity of the suspension effectively, thus preventing the ACM powders from settling and improving the stability of the suspension [ 36 ]. The molecular chain of polyethylene glycol provided a spatial barrier shield, which effectively prevented the agglomeration of ACM powders.…”

Preparation and Performance Evaluation of a Variable Viscosity Friction Reducer Suspension with High Salt Tolerance and Low Damage

“…This makes it possible to meet the requirements of continuous inline mixing and simplifies the complex mixing process. 20,21 Wei et al 22 synthesized an integrated friction reducer with high viscosity and high drag reduction using acrylamide, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid. At a flow rate of 150 L/min, the drag reduction of both low-viscosity and high-viscosity slickwater was greater than 70%.…”

“…Slickwater and cross-linking fluid need to be prepared in advance for each stage, and the alternating pumping process of the two working fluids is complex, resulting in low fracturing efficiency and high cost. , The integrated slickwater can not only make use of the produced water for continuous in-line mixing but can also realize the instant switch between slickwater and cross-linking fluid through adjusting the friction reducer concentration. This makes it possible to meet the requirements of continuous in-line mixing and simplifies the complex mixing process. , Wei et al synthesized an integrated friction reducer with high viscosity and high drag reduction using acrylamide, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid. At a flow rate of 150 L/min, the drag reduction of both low-viscosity and high-viscosity slickwater was greater than 70%.…”

Study on the Relationship between the Relative Molecular Mass of a Polymer Clay Stabilizer and the Permeability of a Tight Reservoir

“…With the continuous growth of global oil and gas demand, more and more countries gradually shift their focus to the exploration and development of unconventional oil and gas resources. 1 , 2 Tight oil and gas, which are kind of unconventional oil and gas recourses, refer to hydrocarbons buried in tight reservoirs, which are characterized by the permeability equal to or less than 0.1 × 10 –3 μm 2 . 3 , 4 Because of their low permeability, hydraulic fracturing is the most important stimulation technology to improve oil and gas production.…”

“…Oil and gas are indispensable fossil fuels for human beings’ life and industrial development. With the continuous growth of global oil and gas demand, more and more countries gradually shift their focus to the exploration and development of unconventional oil and gas resources. , Tight oil and gas, which are kind of unconventional oil and gas recourses, refer to hydrocarbons buried in tight reservoirs, which are characterized by the permeability equal to or less than 0.1 × 10 –3 μm 2 . , Because of their low permeability, hydraulic fracturing is the most important stimulation technology to improve oil and gas production. , However, the invasion of fracturing fluids into the reservoir rocks will cause permeability damage to the tight reservoir matrix, such as water-sensitivity damage and water-locking damage …”