Hydraulic Fracturing on Water from Alternative Sources: An Integrated Approach, Ways, and Solutions

Abstract

In the context of a comprehensive search for ways to optimize and reduce operating costs for hydraulic fracturing operations, one of the areas to consider is the use of alternative water sources for making-up hydraulic fracturing fluids such as Cenomanian, mixed or produced water. This solution allows to optimize the speed and quality of work without wasting time and financial resources due to no need for heating and remote transportation. The main goal of the study was to create a stable guar-based hydraulic fracturing fluid system with a borate crosslinker, which allows high-quality treatment using high-salinity water. Much attention is paid to the composition of real saline sources, i.e. produced, mixed and Cenomanian water, which were sampled from the Gazpromneft-Khantos fields. Based on the data ranking by composition, the main groups of mineral components, as well as the cut-off criteria that determine the behavior of a hydraulic fracturing fluid in linear and cross-linked forms, were identified. The main stage of working on the fluid system quality included two areas: screening stabilizing components that meet the criteria for performing hydraulic fracturing operations, and assessing the fluid clogging properties based on flow tests. To study and select the composition of a hydraulic fracturing fluid, both standard and extended rheological tests were performed, which included core tests on real samples from target reservoirs and tests of residual conductivity and permeability of a proppant pack. The sand-transport properties of the fluid were measured both in static and dynamic conditions. The study resulted in the development of a fluid system complex including stabilizing additives and criteria for their applicability at real field conditions, taking into account the features of the existing equipment of hydraulic fracturing fleets. Experiments have shown that standard guar fluids based on water from alternative sources, when using a complex of stabilizing components, successfully replace the basic set of additives for fresh water, and are quite competitive not only in rheological properties and the ability to transport proppants, but also in restoring the permeability of a proppant pack and core samples. Each stabilizing component of such fluid makes its own unique contribution to achieving the required parameters of the fluid without losing its quality. An important achievement is the development of methods and criteria for the applicability of stabilizing components that make it possible to work with any source, whether it is produced, mixed, or Cenomanian water. The solution allows in a short time to adjust the fluid system depending on the actual mineral composition in a stationary field laboratory without the involvement of specialized equipment and expensive research.