Produced Water: Influence of Organic Acids on the Gelation of Fracturing Fluids

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201611, “A Pilot-Scale Evaluation of Natural-Gas-Based Foam at Elevated Pressure and Temperature Conditions,” by Griffin Beck, Swanand Bhagwat, and Carolyn Day, Southwest Research Institute, et al., prepared for the 2020 SPE Annual Technical Conference and Exhibition, originally scheduled to be held in Denver, 5–7 October. The paper has not been peer reviewed. The complete paper presents recent results from a rigorous pilot-scale demonstration of natural-gas (NG) foam over a range of operating scenarios relevant to surface and bottomhole conditions with a variety of base-fluid mixtures. The NG foams explored in these investigations exhibited typical shear-thinning behavior observed in rheological studies of nitrogen- (N2) and carbon-dioxide- (CO2) based foams. The measured viscosity and observed stability indicate that NG foams are well-suited for fracturing applications. Test Facilities Two test facilities were used to explore properties of NG foams at a variety of relevant operating conditions to determine whether NG foam is a suitable alternative to typical water-based fracturing fluids. Pilot-Scale Foam-Test Facility. The pilot-scale foam-test facility (PFTF) is a single-pass pilot plant used to generate and characterize foams at conditions relevant to surface and reservoir conditions. The facility is capable of generating aqueous and oil-based foams using a variety of gases for the internal phase [e.g., methane (CH4), N2, and CO2]. Foams can be characterized at pressures up to 7,500 psi and temperatures up to 300°F. A key benefit of the PFTF is that it can be used to demonstrate new or challenging foaming processes before large-scale or field demonstrations. Further, these processes can be evaluated at conditions relevant to the final application. The test facility consists of three subsystems: a base-fluid system to pressurize and heat the liquid/viscosifier/surfactant mixture, a gas system to pressurize and heat the liquefied gas stream, and the foam test sections to measure various fluid properties of the NG foam. Laboratory Foam-Test Facility. Tests performed on the PFTF were limited to foams generated with pure CH4 and tap water. Additional laboratory tests were conducted to investigate the effects of multiconstituent natural gas mixtures and produced water on foam stability. For these tests, the aqueous base fluid for the foam half-life and foam rheology experiments was prepared from either de-ionized water, tap water, or a synthetic produced water based on a water sample from the Permian Basin. Foam fracturing fluids also typically contain a gelling agent and a foaming agent. The gel was prepared by slow addition of guar to a stirred water sample followed by 30 minutes of mixing to ensure complete hydration. The foaming agent was added and stirred in gently. Three foaming agents were used in this study: anionic Foamer A, nonionic Foamer B, and zwitterionic Foamer C.

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Modeling Viscosity Response of Fracturing Fluids from Flowback and Produced Water Uing Advanced Cooperative Optimization Algorithms

10.2118/166090-ms ◽

2013 ◽

Author(s):

L.K. Fontenelle ◽

D. Chen ◽

E. Schnoor ◽

J. Haggstrom ◽

D. Perkins

Keyword(s):

Produced Water ◽

Optimization Algorithms ◽

Fracturing Fluids

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Fracturing Fluids from Produced Water

10.2118/173602-ms ◽

2015 ◽

Cited By ~ 4

Author(s):

Sarkis Kakadjian ◽

Joseph Thompson ◽

Robert Torres

Keyword(s):

Produced Water ◽

Fracturing Fluids

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In vitro cytotoxicity assessment of a hydraulic fracturing fluid

Environmental Chemistry ◽

10.1071/en14010 ◽

2015 ◽

Vol 12 (3) ◽

pp. 286 ◽

Cited By ~ 5

Author(s):

Madeleine E. Payne ◽

Heather F. Chapman ◽

Janet Cumming ◽

Frederic D. L. Leusch

Keyword(s):

Coal Seam ◽

Hydraulic Fracturing ◽

Human Health ◽

Produced Water ◽

Coal Seam Gas ◽

Fracturing Fluid ◽

Human Health Risks ◽

Fracturing Fluids ◽

Hydraulic Fracturing Fluid

Environmental context Hydraulic fracturing fluids, used in large volumes by the coal seam gas mining industry, are potentially present in the environment either in underground formations or in mine wastewater (produced water). Previous studies of the human health and environmental effects of this practice have been limited because they use only desktop methods and have not considered combined mixture toxicity. We use a novel in vitro method for toxicity assessment, and describe the toxicity of a hydraulic fracturing fluid on a human gastrointestinal cell line. Abstract Hydraulic fracturing fluids are chemical mixtures used to enhance oil and gas extraction. There are concerns that fracturing fluids are hazardous and that their release into the environment – by direct injection to coal and shale formations or as residue in produced water – may have effects on ecosystems, water quality and public health. This study aimed to characterise the acute cytotoxicity of a hydraulic fracturing fluid using a human gastrointestinal cell line and, using this data, contribute to the understanding of potential human health risks posed by coal seam gas (CSG) extraction in Queensland, Australia. Previous published research on the health effects of hydraulic fracturing fluids has been limited to desktop studies of individual chemicals. As such, this study is one of the first attempts to characterise the toxicity of a hydraulic fracturing mixture using laboratory methods. The fracturing fluid was determined to be cytotoxic, with half maximal inhibitory concentrations (IC50) values across mixture variations ranging between 25 and 51mM. When used by industry, these fracturing fluids would be at concentrations of over 200mM before injection into the coal seam. A 5-fold dilution would be sufficient to reduce the toxicity of the fluids to below the detection limit of the assay. It is unlikely that human exposure would occur at these high (‘before use’) concentrations and likely that the fluids would be diluted during use. Thus, it can be inferred that the level of acute risk to human health associated with the use of these fracturing fluids is low. However, a thorough exposure assessment and additional chronic and targeted toxicity assessments are required to conclusively determine human health risks.

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Enhancing Performance of High Viscosity Friction Reducers HVFRs in Brine

10.2118/204339-ms ◽

2021 ◽

Author(s):

Alhad Phatak ◽

Brian Seymour ◽

Ginger Ren ◽

Isaias Gonzalez

Keyword(s):

Produced Water ◽

High Viscosity ◽

Fluid Viscosity ◽

Concentric Cylinder ◽

Rectangular Slot ◽

Shear Rates ◽

Fracturing Fluids ◽

Wide Range ◽

Obvious Benefit ◽

Produced Waters

Abstract High Viscosity Friction Reducers (HVFRs) are often employed in hydraulic fracturing fluids to increase the proppant carrying capacity of slickwater fluids. However, it has been widely reported that the performance of HVFR fluids drops precipitously with even small amounts of salt. This study explores and reports the use of surfactants to alleviate the loss of performance of HVFR fluids due to salinity in the mix water. Fracturing fluids were prepared in the laboratory by mixing the HVFR at concentrations between 2 and 8 gal/1,000 gal with and without surfactant formulations. The viscosities of the fluids were measured on a TA Instruments DHR-3 rheometer using a concentric cylinder geometry. Both anionic and cationic HVFRs were tested with various surfactants. As expected, we observed that HVFR fluids display dramatic loss of viscosity with the addition of as little as 1% salt to the mix water. However, certain surfactant formulations were found to provide a significant boost in viscosity of HVFR fluids in brines over a wide range of shear rates. Increases in viscosity by a factor of as much as 10 times were observed, particularly at low shear rates. The ability of the surfactant formulations to enhance fluid viscosity was observed in both monovalent and divalent model brines, as well as brines that mimicked field produced water compositions. In addition, measurements were also performed in a slot flow device to determine if the results from the rheometer translated to proppant transport characteristics of the fluids. The slot flow results were found to correlate well with fluid viscosity measurements. The fluids containing the surfactant formulation transported nearly 4 times as much proppant as fluids not containing surfactant through a 2.5 ft. long rectangular slot of 0.5 in. thickness at a proppant concentration of 2 lb/gal. An obvious benefit of the approach proposed in this study is that it can enable the use of HVFR fluids in recycled and produced waters, providing both cost and sustainability benefits. Secondly, these surfactant formulations can reduce the amount of HVFR required to obtain a certain target viscosity in brine, thereby reducing the likelihood and potential severity of formation damage from HVFR residue.

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A Comprehensive Review on the Characteristics, Challenges and Reuse Opportunities Associated with Produced Water in Fracturing Operations

10.2118/207835-ms ◽

2021 ◽

Author(s):

Mustafa Ahmed Alkhowaildi ◽

Mohamed Mahmoud ◽

Mohammed Abdullah Bataweel ◽

Bassam Tawabini

Keyword(s):

Hydraulic Fracturing ◽

Water Conservation ◽

Energy Demand ◽

Base Fluid ◽

Produced Water ◽

Waste Product ◽

Field Trials ◽

Critical Parameters ◽

Hydration Time ◽

Fracturing Fluids

Abstract Amid the rise in energy demand over recent years, natural gas from tight reservoirs has been targeted abundantly around the globe by different oil operators. Hydraulic fracturing technology has been instrumental in the successful exploitation of energy from tight formations. The process is associated with enormous usage of water. Hydraulic fracturing requires as little as 500,000 gallons of freshwater, and up to 6 million gallons per well depending on the type of well and the number of stages treated. Now operators, as well as service companies worldwide, have shown a desire to use produced water in field operations to enhance economics and reduce their environmental footprint. Reusing produced water in field operations appears to be a win-win proposition by transforming the industry's biggest waste product into a resource. This paper highlights the recent findings in published articles about formulating a fracturing fluid from produced water as a base fluid. The rheological properties and fluid performance requirements, such as proppant carrying capacity, mixing, fluid efficiency, ability to crosslink and break, and cleanup after treatment, will be evaluated in detail. This paper identified the critical parameters associated with high TDS fluids (produced water) such as pH, hydration time, ionic strength, and suspended solids, collected the corresponding optimal ranges for these parameters in laboratory tests, and reported some of the validity of the findings under actual conditions in field trials around the world. Most studies demonstrated the feasibility of using untreated produced water as a base fluid for crosslinked gel-based hydraulic fracturing. Through adjusting the hydration time, the gel loading, and the amount of breakers applied, it is conceivable that crosslinked gels with optimal rheological characteristics can be formulated with untreated produced water. Multiple generations of guar- and CMHPG-based crosslinked fracturing fluids, developed with 100% untreated produced water, exhibited optimal viscosities exceeding 200 cp at 40 s−1 for at least 60 minutes. The ability to provide fracturing fluids with high-salinity produced water can be a successful water conservation approach and an attractive solution for enhancing operation economics. Some studies indicated that using produced water can be better than freshwater because the produced water is more compatible with the reservoir and may be less likely to cause conditions such as salinity shock, which can damage the formation. More studies are needed to understand the associated technical challenges further.

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