Evaluation of Coated Proppant Unconventional Performance

摘要

Fracturing is a key stimulation measure in hydrocarbon exploration and development. The proppant, which is the core material in fracturing, is the key in improving the fracturing success rate and the stimulation effect. The coated proppant is made by coating a polymer resin on the aggregate body of the traditional proppant. The coated proppant has the low density, high strength, and low crushing rate and is widely used in reservoir fracturing and sand control. Nevertheless, the standards for evaluating coated proppant performance have not been presented. Especially, experiments on the effect of temperature on the conductivity of the fracture filled with coated proppants and the migration and settlement of the coated proppants within the fractures have rarely been reported. In this study, the solubility in alkali, wettability, and high-temperature (HT) deformation property of the coated proppant were tested, and the dynamic migration and settlement physical simulation were performed to evaluate the unconventional performance and the applicability of the coated proppant. The experiment on HT deformation of the coated proppant was performed in a HT seepage simulator, and the proppant migration and settlement physical simulation was performed in a large-scale visual plate simulator of proppant migration. Both devices have been independently designed and manufactured by China University of Petroleum (UPC). The results show that the coated proppant solubility in alkali gradually increases with an increase in pH and temperature of the fracturing fluid, and all three types of coated proppant are water-resistant and oil wet. At high temperature and under high pressure (150 degrees C and 30 MPa), the coated proppant deforms and melts significantly, and the particles adhere mutually and are crushed, causing a reduction of 2 orders of magnitude in the permeability of the fracture filled with proppants. The migration capacity of the ultralow-density (ULD)-coated proppant is significantly better than that of the medium-density (MD)-coated proppant and conventional-density (CD) proppant in the major and branch fractures. The bank height of the ULD-coated proppants is obviously lower than those of the MD-coated proppants and the CD proppants, and the bank heights of the MD- and CD-coated proppants are 5.6 times and 6.7 times that of the ULD-coated proppants, respectively. The ULD-coated proppants are more easily carried by the fracturing fluid and migrate to the far end of the fracture.