In the Golfo San Jorge basin (GSJB), in the area of Cerro Dragón, a sustained increase of activity has developed over the past ten years. Further development of the field has been achieved with well stimulations (hydraulic-fracturing treatments), increasing production rates. This has resulted in increased water consumption for these operations. In an effort to ration water sources, well owners must find alternatives to reduce the volume of fresh water consumed. Throughout the past five years, one operator has worked to use produced water, or low-quality injection water, as a source of water for stimulation applications. The methodology applied consisted of Identifying different types of water produced in the fieldPerforming tests on the waters (physical-chemical and bacteriological)Performing tests with commonly used fracturing fluids to identify good performanceConducting tests during field operationsEstablishing procedures for water injection from the results obtainedContinuous monitoring, as well as the introduction of new techniques and improvements The results that were obtained demonstrate how the operations performed have gradually increased by using this methodology (412 of 760 fracturing treatments during 2010). In addition, the reduction in freshwater use was 54.8% of the total amount in 2010 (5.7 of 10.5 million gal). This work has helped identify sources of produced water in the field that are acceptable for use in fracturing stimulation operations. A procedure has been established to help ensure a reliable fracturing fluid with good performance is always used in these operations. Additionally, new techniques and equipment have been incorporated that contribute to continuous improvements to the process.
This paper documents pinpoint fracturing (PPF) in Argentina. The implementation of this method has resulted in 193 fractures in 22 wells since October 2006. The PPF method creates perforations by pumping abrasive slurry down the coiled tubing (CT) through a jetting nozzle, while the main treatment is then pumped down the annulus around the CT. Isolation between fracture treatments is accomplished using sand plugs (preferred method) or composite bridge plugs. This technique has allowed greater selectivity in the stimulation of the areas to be treated; it has also allowed a more aggressive fracture treatment in terms of percent pad and the final proppant concentration because the CT is at the location in case of screen out. In gas fields, it offers the advantage of completing the well without killing it. Different reservoirs with varying depths, temperature, types of fluid, and petrophysical conditions in the basins Golfo San Jorge and Neuquina were stimulated with different fracture fluids, proppant types, and frac gradients. The Neuquina basin required fracturing without using a workover rig in oil and gas fields near the community, while significantly diminishing the working times with a reduction in environmental impact and noise generated during the completion. However, the main goal was the reduction of completion times in each well performed in the different basins of Argentina. Introduction New hydraulic-fracturing technologies introduced in Argentina not only provide application of new products or processes; but, their versatility allows them to be used in different types of reservoirs and conventional completion practices. On evaluation of different technologies, it is assumed that the selected technology and its application should lead to diminished completion times and cost, as well as improve selectivity and production. Based on these criteria, it was determined that hydrajet-perforating annular-path treatment-placement and the proppant plugs for diversion (HPAP-PPD) method using CT could fulfill the expected needs. This study shows the application of this in various fields, focusing on each of them to solve problems, such as application in mature fields, gas reservoirs, and low-permeability sands. The value of HPAP-PPD is well documented in vertical-well completions in many areas in the U.S. (East et al. 2005; Fussel et al. 2006; Helj et al. 2006; Peak et al. 2007), Australia (Gilbert et al. 2005; Beatty et al. 2007) and Russia (Pongratz et al. 2008). The maximum number of individual fracture treatments performed on a single well outside of North America is currently 30, performed on a well in Argentina, although no usage limitation for the method is known. Description of HPAP with Proppant Plug Diversion (HPAP-PPD) Using CT, hydrajet perforating, annular-path treatment placement, and proppant plugs for diversion, the (HPAP-PPD) method was introduced to the industry in 2004 (Surjaatmadja et al. 2005). Initial work with the method was related to vertical-well completions. The method overcame the need for monobore completions because there were no mechanical devices to set inside the casing.
During workover and completion operations, even a small overbalanced hydrostatic pressure can result in a significant loss of fluid to the formation, especially in high-permeability formations. This situation becomes even more drastic in depleted reservoirs, horizontal wells, or in zones that have been previously fractured and packed. Controlling fluid loss into the formation is of critical importance during overbalanced workover operations to minimize near-wellbore (NWB) damage invasion by the completion fluid, which can yield problems associated with poor wellbore cleanout and loss of hydrocarbon reserves. In addition, fluid loss can increase costs associated with rig time and treatments devoted to restore the initial condition of the formation. In many hydrocarbon fields in southern Argentina, controlling fluid loss before NWB cleanout treatments is challenging because it can cause pressure differential sticking of the coiled tubing (CT) and/or inability to pump the treatment into the desired interval. This paper presents the successful field application of a novel solids-free fluid-loss (SFFL) system during wellbore cleanouts in the Cerro Dragon oilfield, which is located on the west side of San Jorge Gulf (SJG) basin in the Chubut Province of Argentina.The SFFL system relies on water-soluble polymer that decreases matrix permeability to aqueous fluids, limiting leakoff into treated zones. This polymer immediately adsorbs to the surface of the rock, eliminating the need to shut the well in. In addition, this system does not require the use of breakers or a cleanup stage to reestablish hydrocarbon production once the workover operation has been performed. Laboratory test data show the capability of the material to control fluid leakoff and achieve high levels of regained permeability to hydrocarbons. Traditional techniques to minimize fluid loss use solids or viscous pills, although it has been amply documented that these systems can damage the formation if not properly removed after the treatment.To date, about 200 treatments have been performed with this novel SFFL system. The paper discusses field results from the application of this system during overbalanced workover operations in Argentina, including the job design and posttreatment results. This system has been proposed for returning partial and total loss to full circulation in overbalanced operations, such as (1) lost-circulation events occurring during cementing, fracturing and drilling, (2) well intervention cleanouts by CT and hydraulic workover (HWO), (3) gravel packing, (4) replacement of artificial lift equipment (i.e., electrical submersible pumps), and (5) overbalanced tubing-conveyed perforating (UTCP).
This work builds on Bonapace et al. (2015), specifically discussing shale reservoir information related to several tight reservoirs in Argentina.Hydraulic fracturing has been ongoing in Argentina since the 1960s. The first treatments were performed using oil-based fluids. Throughout the years, new water-based fluids were introduced, as well as alcohol-water mixture fluids to foams, based on the reservoir requirements, economics, and safety and environmental issues. Currently, more than 95% of hydraulic fractures performed in the country are performed using aqueous-based fluids.In the last 10 years, exploration and development has begun for tight gas reservoirs and more recently several shale plays. To achieve commercial production, this type of reservoir requires extensive hydraulic fracturing applications which use large volumes of water. From 2004 to present, various exploration techniques have been performed in different reservoirs, such as tight formations at Lajas, Punta Rosada, Mulichinco (Neuquén Basin); Potrerillos (Cuyo Basin); D-129 (Golfo San Jorge Basin) and shale plays at Los Molles, Vaca Muerta, Agrio (Neuquén Basin), Cacheuta (Cuyo Basin), and D-129 (Golfo San Jorge Basin).This paper discusses aspects of water logistics necessary during the well completion phase, fracture treatment designs applied within these various unconventional reservoirs, and laboratory studies performed on flowback and produced waters to help evaluate their potential for use and/or reuse. The primary focus here will be related to various parts of the water cycle for these projects.• Stimulation and water sources are presented as detailed information concerning the type of stimulation performed in these reservoirs, volume of water, treatment types, fracturing fluids, additives used, and physical-chemical characteristics of various freshwater sources used. • Logistics are discussed for water storage and transport for single and multiple well pads. • Reuse of flowback and formation water addresses laboratory testing of various flowback and formation water and/or blends (freshwater and flowback water), treated and untreated including:-Physico-chemical characteristics of water (flowback and produced) from various wells.-Formation sensibility testing with flowback water from various tight and shale formations and usage possibilities. -Impact on proppant packs of floculants generated in nontraditional waters at various pH values. -A new low-residue CMHPG-metal crosslinked fracturing fluid formulated using no traditional water, i.e., untreated with high total dissolved solids (TDS).
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