Proppant Flowback Prevention and Control by Analysis of Early Time Well Production Data

Abstract

Abstract Proppant flowback during the post-stimulation well clean up and production is a common occurrence in most hydraulically fractured wells. Whilst some proppant is expected to be produced during the well cleanup operations that typically follow the treatment execution, the long-term production of proppant can be problematic from an economic viewpoint. A thorough analysis of early time production data can be used to develop guidelines that can aid in minimizing the proppant flowback and associated issues. It is a well-known fact that the production of the proppant from a propped fracture is related to the forces acting on the proppant pack during the well that is actively producing fluids. Some of these, e.g., increase of effective stresses on the proppant, are stabilizing in nature, whereas others related to inertial flow from fluid velocity, viscosity and others can destabilize the pack. Most proppant flow back related studies associate the proppant production with critical flow velocities that are prevalent for given flowing conditions. This important parameter is thus a key to predicting proppant production during the well's producing life. In this study, flow rate and pressure data collected during the post-treatment flowback activity is used in simulating bottomhole (BH) production rates with the help of calculations. Using Gaussian solution scheme, the BH rate is distributed amongst the various perforation clusters while incorporating the effects of key hydraulic fracture characteristics in presence of simulated effective bottomhole flowing pressures across each fluid entry point into the wellbore. The solution is updated at each time step during the simulation. The production allocation is then used for calculation of effective flow velocities which are then compared with critical velocities to determine if proppant production can occur. Steps to mitigate or reduce the flowback, if present, are then recommended based on the analysis. In the flowback model developed during the study, flowing bottomhole pressures at each sleeve depth was generated with the help of hydrostatic and frictional pressures, and used in forward calculation of total flow rate at downhole conditions. The bottomhole flowrate was then allocated across various sleeves and finally, the associated production fluid velocities were calculated. These were compared with critical velocities corresponding to the fracture associated with each of the sleeves (or perforation set) to determine if there was potential of proppant flowback under the prevailing conditions. The procedure developed in the study can help in diagnosing conditions that may lead to proppant flowback and thus aid in preventing it by adjusting the controllable parameters during the treatment design and production phase. This technique can be easily implemented on similar completions worldwide.