Abstract

The unconventional Vaca Muerta (VM) boom in Argentina has led operators to explore other targets, including tight-gas formations and shale oil formations, in different provinces and basins. For these projects, the primary objective was to evaluate the feasibility of using alternative sources of water for hydraulic fracturing. The customization of a fracture fluid with these types of water has had two goals. The first goal is an environmental focus, according to the geographic field locations; the second goal focuses on costs and includes both the reduction of completion costs and the improved profitability for these projects. This paper documents and summarizes three cases in which a tailored fracture fluid was developed using these nontraditional sources of water.

Case histories, including the Austral basin (Magallanes formation, a tight-gas reservoir), Golfo San Jorge basin (Diadema-129 formation, a shale oil reservoir), and Neuquina basin (VM formation, a shale oil in Mendoza province) are presented. The paper describes the scope of work for each project, sources of water evaluated, and laboratory methods applied to evaluate a customized crosslinked fracture fluid to meet the operational requirement. A summary of the total jobs performed and the total water volume used for these nontraditional water sources has been included.

A database was developed to collect the primary information required to formulate these fluids. The data are classified into three data groups. The Completion and Stimulation group provides the base information for this work and includes bottomhole temperature, pumping time, and well configuration. The second group, Water Analysis (physical-chemical), includes valuable information used to identify the deviations from the baseline standard for fresh water. The third group includes a full fluid test that consists of hydration gelling curves, a dynamic rheology test (downhole condition), a stability and break test, and a variable shear rate test.

Several types of fluid were tested for these nontraditional water sources, including a guar-borate fluid and a derivatized guar- (CMHPG) zirconate fluid. To develop a solution that would not economically affect the project, the focus was to evaluate the guar-borate system; a different type of boron crosslinker was tested. Finally, a tailored fracture fluid was developed for each project, using the different boron crosslinker, in accordance with the characteristics of the water sources.

The use of alternative water sources to formulate tailored fracture fluids enabled operators to explore or develop unconventional targets in environmentally sensitive areas. In addition, this type of solution contributes to an improved project economy, which reduces completion costs.

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