A new technical standard has been developed for assessing the performance and physical characteristics of heavy brines used in completion, packer, and drill-in operations. This technical standard includes procedures for evaluating the density, specific gravity, clarity, amount of suspended particulate matter, crystallization point, pH, and iron contamination. It also contains a discussion of gas hydrate formation and mitigation, brine viscosity, brine crystallization at high pressures, corrosion testing, buffering capacity, and a standardized reporting form. Introduction The American Petroleum Institute (API) has developed recommended practices (RP) for testing heavy brines. These recommended practices have been generated and documented by brine experts from industry under the auspices of API Committee 3, Subcommittee 13, Task Group 6. The first recommended practice for clear completion brines was published June 1, 1986 as "API Recommended Practice 13J Recommended Practice for Testing Heavy Brines" (RP-13J) [1]. This document contained three sections: Brine Density, Brine Crystallization Temperature, and Brine Clarity. Each section of the document was enhanced in the Second Edition[2] published March 1996. The Third Edition[3] was published December 2003 and greatly expanded the scope of RP-13J. In addition to substantially upgrading the existing sections of the document, the Third Edition added four new sections and six annex sections. The new additions to RP-13J are titled:Section 9Solids evaluation by gravimetric procedures,Section 10pH,Section 11Iron contamination,Section 12Daily completion fluid report,Annex ACompletions Fluid Report Form,Annex BGas Hydrates,Annex CBuffering capacity of brines,Annex DPressure crystallization of brines,Annex EBrine viscosity, andAnnex FPrinciple of corrosion testing. As we entered into the 21st Century, it became abundantly clear that recommended practices and standards needed to be globalized. Consequently, the API and authors of the Third Edition of RP-13J transformed that edition into the format required by the International Organization for Standardization (ISO). The resulting document, " Petroleum and natural gas industries- Completion fluids and materials- Part 3: Testing of heavy brines" [4] was generated and given the designation "ISO 13503–3: Testing of heavy brines" or more commonly ISO 13503–3. As of this writing, the document was being circulated in Final Draft for vote that will conclude in November 2005. This document and its counterpart API RP-13J (3rd Edition) are "living documents" that undergo continual enhancement. By convening appropriate work groups, Task Group 6 will continue to expand and update the documents, and provide procedures and standards for new sections such as buffering capacity and pressure crystallization. The purpose of this paper is to communicate information about the document "ISO 13503–3: Testing of heavy brines" to the oilfield industry, particularly to those engineers involved with the use and maintenance of clear completion brines.

Quantifying total iron in brine is critical in order to mitigate its unfavorable effects. An API-sponsored work group has developed a robust field method for determining the levels of iron contamination in all oilfield completion brine, including zinc-based brine. This colorimetric, semi-quantitative method is based on chemistry involving acidification, peroxide oxidation, and thiocyanate complex formation. The iron content is quantified by comparing the intensity of the resulting colored complexes to standards. Using newly-developed, commercially available vacu-ampoule test kits (Figure 1), this assay is quick and particularly user-friendly, and it is easily implemented in the field. It is anticipated that this method will be incorporated into the API Recommended Practice 13J, Testing of Heavy Brine. Introduction Accumulation of iron salts in a brine completion fluid can lead to significant formation damage and greatly affect the productivity of a well. In addition, iron can cause cross-linking and gelling of polymers and increase the stabilization of crude/brine emulsions. Quantifying total iron in brine is critical in order to mitigate its effects. Iron contamination in oilfield brine typically is a result of corrosion processes of iron-containing metallic components and equipment. This can occur in both aerobic and anaerobic environments, either electrochemically or microbiologically-induced. In the corrosion process, metallic iron is first converted to Fe+2 [the ferrous cationic species] with the loss of two electrons. Fe+2 can be converted to Fe3 [the ferric cationic species] with the loss of an additional electron. The electron acceptor depends on the environment and the configuration of the system. Generally, Fe+2 salts are water soluble, and Fe+3 salts are water insoluble. Background In 1994, Subcommittee 13 Task Group 6 convened a Work Group to develop a field-friendly assay for iron quantification in heavy brine that would be effective across the full range of halide and organic brine. Inductively Coupled Plasma (ICP) and Atomic Absorption (AA) techniques with matrix matching work well, but these methods require expensive equipment, high levels of chemical expertise, large and controlled physical settings, and extensive laboratory manipulation. Neither of these techniques is readily amenable to field application. Prior to the development of the new technique, the Work Group evaluated a number of alternative methods. Many of these are familiar to the oilfield, water, and wastewater industries, but do not work well in brine containing even minor levels of zinc bromide. This includes the standard self-filling ampoules (1,10-phenanthroline chemistry) iron assay commonly used for low-density brine and wastewater analyses. Other techniques considered, including reactive colorimetric strips, were shown to have poor accuracy below 75 ppm iron, to have a high degree of sensitivity to moisture and temperature, or to require development with strong acids. A proposed spot test showed poor reproducibility in round robin exercises. The limitations detailed above were addressed using a spectrophotometric technique. The sample was acidified, oxidized with peroxide, and complexed with thiocyanate. A quantitative result was determined using a hand-held single-wavelength spectrophotometer with blanks and a calibration curve. Although the technique addressed the zinc issue, the extensive sample, standard, and reagent preparation made this technique difficult for field applications.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA new technical standard has been developed for assessing the performance and physical characteristics of heavy brines used in completion, packer, and drill-in operations. This technical standard includes procedures for evaluating the density, specific gravity, clarity, amount of suspended particulate matter, crystallization point, pH, and iron contamination. It also contains a discussion of gas hydrate formation and mitigation, brine viscosity, brine crystallization at high pressures, corrosion testing, buffering capacity, and a standardized reporting form.

A major operator in the Gulf of Mexico (GOM) desired to increase oil production to meet growing energy demand. To meet this challenge, the operator explored an alternate completion design to mitigate reservoir damage observed in previous producing wells and collaborated with the fluids provider to design a solution to address this concern. The design and solution ultimately applied resulted in "negative skin" with production rates far exceeding historical field rates. Additionally, the operator realized significant cost savings with this change in completion approach by eliminating traditional steps. The development field had its unique challenges with ongoing depletion, wellbore instability risks, and compartmentalization in the reservoir, making access to thinner oil reservoirs challenging to develop. The standard completion approach was to drill with a synthetic-based fluid, perforate the casing, and perform a frac-pack completion. Using technology from another region, the operator elected to change the traditional cased hole frac-pack approach to drilling horizontally through the reservoir, run production screens, and perform an open hole gravel pack completion. In the fluids design phase, the fluids provider performed hydraulics modeling and laboratory testing on multiple formulations, including brine compatibility with formation water; formation response testing; high-pressure/high-temperature (HPHT) rheology and fluid loss; static age testing for intervals of 16 hours, 3 days, and 5 days; and contamination testing with solids, synthetic-based mud, and cement. This paper discusses the methodology used in the design phase required to engineer a reservoir friendly fluid to meet the challenges faced with this complex well.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractQuantifying total iron in brine is critical in order to mitigate its unfavorable effects. An API-sponsored work group has developed a robust field method for determining the levels of iron contamination in all oilfield completion brine, including zinc-based brine. This colorimetric, semi-quantitative method is based on chemistry involving acidification, peroxide oxidation, and thiocyanate complex formation. The iron content is quantified by comparing the intensity of the resulting colored complexes to standards.Using newly-developed, commercially available vacuampoule test kits (Figure 1), this assay is quick and particularly user-friendly, and it is easily implemented in the field. It is anticipated that this method will be incorporated into the API Recommended Practice 13J, Testing of Heavy Brine.