Measurement of the Static Proppant-Settling Velocity in Fracturing Fluids Through Digital Image Analysis

Abstract

Abstract This paper presents a novel method for quantitatively measuring the static proppant-settling velocity in hydraulic fracturing fluids through digital image analysis. The method developed is reliable and efficient for measuring the static proppant settling velocity (Sv) when there is no clear settling interface, which is useful for comparing the proppant carrying capability of different friction reducers (FRs), optimizing the concentration of friction reducers in the fracturing fluids for field operations, and improving the proppant carrying capability of friction reducers through the synthesis process. The experimental procedure involves pouring a fracturing fluid with proppants into a transparent glass cylinder, taking images of the proppants settling using a camera, transferring the images into a computer, and analyzing the images using macro programs prepared to measure the static proppant settling velocity. The settling velocity is determined by measuring the position (height) change of a proppant concentration selected with time, which is realized through using image saturation to determine the position of the proppant concentration in the image analysis. The results obtained from this method show that the proppant size, friction reducer concentration, salinity of the friction reducer fracturing fluids, and friction reducer molecule weight and chemical structure have an impact on the static proppant settling velocity. Also, the method developed in this study can be helpful for selecting proper fracturing fluids for field applications and the optimization of friction reducers in the synthesis process through quantitatively measuring the settling velocity. To the best of our knowledge, except for determining the settling velocity of a single particle in the fluids, this is the first study to quantitatively measure the static proppant-settling velocity in fracturing fluids through digital image analysis. The method developed offers several benefits including the ability to measure the settling velocity in real-time, low cost, and ease of implementation even when there is no clear settling interface. The results obtained from this method provide valuable insights into the transport behavior of proppants in fracturing fluids, enabling better design of hydraulic fracturing treatments to improve the recovery of oil and gas.