Optimization of Slurry Operation Parameters Through the Application of Dynamic Proppant Conductivity Apparatus
Authors: Liu Hai , Yang Xiwu , Zhang Jian , Xiao Yuanxiang , Xu Hongxing , Li Yesong , Zhou Libo , Tan Yanxin , Li Hui , Li Ben 
Published: September 2023

ABSTRACT
During hydraulic fracturing operations, proppants were usually pumped in a small-diameter, medium-diameter, and large-diameter sequence. Thus, the hydraulic fracture was propped by different size and types of proppants. It is found that the slurry operation parameters such as fluid viscosity, sand-slurry ratio, and pump rate could affect proppant migration and settlement in the fractures. It is crucial to evaluate the conductivity of these propped fractures while considering the migration and placement of proppant size and types. This paper proposes practical dynamic fracture conductivity measurement apparatus and procedures that can simulate the process of slurry transport and proppant settlement for the optimization of these slurry operation parameters. Slurry viscosity, pump rate, and sand ratio were obtained and summarized from 35 hydraulic fracturing wells in T dry-gas field, and used to simulate the real sand-laden slurry conditions. The conductivity of fractures propped by different sizes of proppant and different types of proppants was all measured. Results showed that dynamic conductivity increased gradually with ceramic/quartz sand ratio increase. Under the same ceramic/quartz sand ratio, dynamic conductivity decreased gradually with closure pressure increase. Under formation closure pressure, the conductivity of quartz sand with the same proppant size is lower than that of ceramic proppant, and the average conductivity reduction ratio is 36.6% and 45.5% for 30/50 mesh and 40/70 mesh, respectively. The conductivity of 40/70 mesh is lower than that of 30/50 mesh, and the average conductivity reduction ratio is 62.6% and 71.8% for ceramic and quartz sand, respectively. The proposed methodology can be used to optimize proppant and reduce investment in hydraulic fracturing designs and operations.

INTRODUCTION
In tight oil and gas development, it is difficult to improve the overall working quality and efficiency due to the influence of many factors, including reservoir low permeablity and poor porosity and so on (Anderson., 1973; Li et al., 2020; Li et al., 2023). The implementation of hydraulic fracturing technology can achieve the oil and gas production efficiency. Hydraulic fracturing is the technology that fracturing fluid is pumped into the pre-fractured interval through a high-pressure pump so that it reaches the fracture pressure of the oil layer and forms cracks. Then, proppant is injected into the cracks, and the cracks continue to extend, keeping the cracks open (Li et al., 2019; Li et al., 2018). The cracks have a very high percolation capacity for reservoir stimulation (Meng et al., 2022; Gao et al., 2022; Mou., 2017). Hydraulic fracturing can change the flow state of the fluid, eliminate the radial throttling loss, and improve the flow of reservoir fluid. It reduces the resistance of oil flow near the well and provides the seepage capacity of oil flow (Tian et al., 2018; Li et al., 2020; Chen., 2016).