Performance Evaluation of Acid Treatments in Seawater Injectors With
Reference to Two Cleanup Techniques

fax 01-972-952-9435. AbstractNumerous acid stimulation techniques have been employed in water injectors to achieve uniform distribution across the injection interval. Mechanical and chemical diversion techniques were utilized separately and jointly to eliminate high permeability zones or thief zones where most of the injection water is flowing into a thin layer of the injection profile. The choice of placement techniques and chemical diversions plays an important role in the treatment success.This paper presents case histories of acid treatments performance evaluation based on placement and diversion techniques. Based on the calculated time-lapsed injectivity index model and flow-meter surveys, the effectiveness of various mechanical and diversion techniques were evaluated. Placement techniques were either using bullheading or coiled tubing technique. The study covered 49 treatments using bullheading technique and 33 treatments using coiled tubing technique. The chemical diversions included polymer and surfactant-based in-situ gelled acids and foam diversion.Flow meter survey conducted on several seawater injectors indicated that polymer-based acids damaged some zones of the injection interval. This resulted in poor distribution of the injected water. Foam diversion using bullheading technique did not improve the injection profile in the presence of thief zones. Wells treated by placing the acid using CT showed better performance than those wells treated by placing the acid by bullheading. Combinations of mechanical (CT) and chemical diversion (foam) showed better results than using chemical or chemical diversion alone. Viscoelastic surfactantbased acid showed significant increase in the injectivity index.

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“…19 The II equation consists of three variables, Eq. 19 The II equation consists of three variables, Eq.…”

Section: Analytical Time-lapsed Injectivity Index Modelmentioning

confidence: 99%

Performance Evaluation of Acid Treatments in Injector Wells With Reference to Division Techniques

2007

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“…This diversion can be accomplished through mechanical, chemical means or both. [6][7][8][9][10][11][12] Many chemical means exist including polymer gels, foams, oilsoluble resins, rock salt, and surfactant gels. 6 Surfactant gels have recently become an increasingly popular choice for viscosifying acidic fluids.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Surfactant-Based Fluids for Acid Diversion

Nasr‐El‐Din¹,

Domelen²,

Sierra³

et al. 2007

Proceedings of European Formation Damage Conference

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fax 01-972-952-9435. AbstractThis paper examines the use of surfactant gels during acid injection and describes the optimization of these fluids. Unlike available viscoelastic surfactants used today in the field, this surfactant is cationic at low pH values. If used in live acids, the fluid has relatively low viscosity when pumped. However, once the acid is spent the surfactant molecules significantly increase the fluid viscosity. To further enhance diversion, the acidic fluid can also be foamed. Alternately, brine gelled with surfactants can be foamed and utilized for diversion.Rheological measurements were conducted on Hastelloy fitted rotational viscometers at temperatures from 70 to 300°F. The effects of surfactant concentration and acid additives on the apparent viscosity of various surfactant-based fluids were investigated in detail.The surfactant was found to be stable and compatible with most acid additives. Some corrosion inhibitors adversely affected the apparent viscosity of surfactant solutions. The apparent viscosity increased with salt concentration. The apparent viscosity of the surfactant solutions can be predicted using Carreau-Yasuda model. Coreflood tests indicated that the surfactant delayed acid breakthrough in carbonate cores. Acceptable corrosion rates were obtained when this surfactant was added to the acid.The performance of this surfactant was validated with field trials. The surfactant was used in more than fifty field treatments. It was used with up to 28 wt% HCl as in-situ acid diverter. It was also used to enhance the stability and apparent viscosity of foams used for acid diversion in power water injectors.

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Performance Evaluation of Acid Treatments in Seawater Injectors With Reference to Two Cleanup Techniques

Cited by 2 publications

References 4 publications

Performance Evaluation of Acid Treatments in Injector Wells With Reference to Division Techniques

Performance Evaluation of Acid Treatments in Injector Wells With Reference to Division Techniques

Optimization of Surfactant-Based Fluids for Acid Diversion

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