Novel Laboratory and Field Approaches to Control Halite and other Problematic Scales in High Salinity Brine from the Bakken

Halite scale is a wide spread problem throughout several basins in the United States. This scale can form in surface equipment, downhole tubulars as well as affecting production. Traditional remediation of halite can be accomplished by dissolving the scale in fresh water as well as recycled water. In most cases the operator must factor in the cost of fresh water, trucking, manpower, anti-scale additives, and disposal of additional produced water. These treatments are often frequent with multiple applications per week. The approach described in this paper will prevent the formation of halite scale for a given period of time. This is accomplished through the use of a new porous ceramic proppant-based chemical delivery system in which a halite inhibitor is infused. The infused halite inhibitor is encapsulated with a semi-permeable membrane to regulate the elution rate of the inhibitor from the porous proppant carrier. The chemical delivery system is added to the bulk proppant as a small weight percentage of the bulk proppant and is placed in the fracture as normal proppant. Several wells in the multiple basins for several E&P companies were completed using this new chemical delivery system, which allowed for a significant amount of halite inhibitor to be placed within the proppant pack. As fluids flowed over the proppant pack the halite inhibitor was slowly released. This paper intends to describe the mechanism for which the inhibitor acts, the control release mechanism of the substrate and the engineering behind the placement and volumes of the halite infused proppant. This paper will also discuss the data collected from laboratory modeling and the implementation of these products in fracturing applications. The use of this chemical delivery system will allow these operators to defer remediation, lowering lease operating expenses. This paper will be useful to all production and completions engineers and technicians operating in an area with halite scale issues. This new chemical delivery system allows for deferred implementation of traditional remediation strategies while extending the most productive time of the wells life. This halite inhibitor delivery system not only improves estimated ultimate recovery but also lowers lease operating expenses.

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Fast and Accurate Screening and Evaluation of Halite Scale Inhibitors by Two Novel Static Bottle Testing Methods

Ruan

Kan

Dai

et al. 2017

Day 1 Mon, April 03, 2017

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Halite (NaCl) scale is a non-conventional scale, which happens due to the temperature or pressure drop, or water evaporation at extremely high TDS environment (TDS up to 350,000 mg/L), such as deepwater field, shale formations, gas and gas condenstate fields. Compared to other conventional mineral scales, like barite or calcite, there is no standardized experimental procedure to screen and evaluate halite scale inhibitors. Because of the extremely high solubility of NaCl, it is very challenging but important to accurately control and calculate the halite saturation index (SI) or saturation ratio (SR) experimentally and theoretically. The Brine Chemistry Consortium has been continuously working on the development and optimization of the thermodynamic model, ScaleSoftPitzer (SSP), for the the prediction of the solubility and scaling risks of various minerals in mixed electrolytes over a wide range of temperature and pressure based on Pitzer theory. Recently the new SSP2017 version which can predict the halite SI within SI error of 0.01 from 25 to 90 °C with up to 1.0 m Ca2+ (~35,000 mg/L). In this study, two static bottle testing methods have been developed by taking the advantage of the powerful calculation ability of SSP2017 to fast and accurately screen and evaluate the inhibition efficiency of different chemicals. The Method One is a temperature-driven and monitoring method and the Method Two is a brine-mixing method of mixing a naturally saturated NaCl solution, a highly concentrated chloride salt solution and an inhibitor solution. By using these two novel methods, over 40 different chemicals are screened and evaluated, including small molecules and polymers in the category of polyacrylate, polyaspartate, polysulfonate, carboxylate sulfonate copolymer, phosphonate polymer, etc. From the experimental results, five carboxylate sulfonate copolymers (Inh #H14, #H23, #H26, #H30, #H40) have better inhibition efficiency. The synergistic effect of Inh #H40 and Fe(CN)64– is also investigated, and 130 mg/L of Inh #H40 and 20 mg/L of Fe(CN)64– can effectively inhibit the halite scale at simulated field condition of SI = 0.09 (SR = 1.23, TDS ~ 353,800 mg/L) and 0.6 m Ca2+ at 70 °C. In summary, two fast and accurate methods have been developed for the screening and evaluation of halite scale inhibitors, and with the usage of effective halite scale inhibitors, the costs of halite scale control can be significantly reduced both in freshwater usage for dilution and high-salinity produced water treatment.

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Novel Laboratory and Field Approaches to Control Halite and other Problematic Scales in High Salinity Brine from the Bakken

Cited by 10 publications

References 18 publications

Inorganic mineral scale mitigation

Inorganic mineral scale mitigation

Prevention of Halite Formation and Deposition in Horizontal Wellbores: A Multi Basin Developmental Study

Fast and Accurate Screening and Evaluation of Halite Scale Inhibitors by Two Novel Static Bottle Testing Methods

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