Experimental Investigation on the Threshold Transportable Concentration of Temporary Plugging Materials of Different Sizes of Slide Sleeves

ABSTRACT The uncased horizontal wellbore is widely used in high-strength formation, especially in low porosity and low permeability carbonate reservoirs to enlarge the drainage area around the whole horizontal section. Multi-staged fracturing and temporary plugging technology are usually used to create complex fracture networks for enhancing well productivity. However, due to the complex geological environments in hydraulic fracturing operations, the sliding sleeve cannot be always fully opened. It is crucial to figure out the threshold concentration of temporary plugging materials at which the temporary plugging materials can be transported through different sizes of slide sleeves. This paper provides an innovative experiment apparatus and experimental procedures to evaluate the transportability of various temporary plugging mixtures concentrations. The proposed sliding sleeve transportability device consists of a 3D migration simulation system, a sliding sleeve simulation device, and a video recording device. The sizes of the sliding sleeve determined by the similarity criterion (the same Reynolds number) are 60mm × 14mm, 45mm × 14mm, and 30mm × 14mm, which can be used to simulate the different degrees of opening the sliding sleeve. Similar criteria that convert filed operation parameters such as pump rate and flow regime to indoor experimental conditions were also proposed. SH-1 well, an uncased horizontal well in the S carbonate reservoir, in China, was used as an example to explore the upper limits concentration of temporary plugging mixtures. The filed temporary plugging displacement is 3m3/min and the carrying fluid viscosity is 12mPa.s. Serial and rigorous experiments were designed to explore the transportability threshold of different sizes of sliding sleeve sizes under different hydraulic fracturing conditions. Results show that the threshold transportability concentration of the temporary mixtures for 60mm×14mm, 45mm×14mm, and 30mm×14mm slide sleeve sizes are 3.2% 4-6mm fiber +2.4% 1-2mm particle, 2.4% 4-6mm fiber +2.0% 1-2mm particle, and 2.0% 4-6mm fiber +1.6% 1-2mm particle, respectively. The proposed experimental apparatus and procedures can be further used to explore the threshold concentrations of temporary plugging materials for other uncased horizontal wells and can provide a theoretical basis for the design of temporary plugging displacement and carrying fluid viscosity.