Delayed-Release Acid System for Cleanup of Al Khalij Horizontal Openhole Drains

Leschi, Pierre; Demarthon, Gilles; Davidson, Eric H.; Clinch, Duncan

doi:10.2523/98164-ms

Cited by 11 publications

(4 citation statements)

References 5 publications

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“…Consequently, it is recommended, when using such esters, to include a specific ester-splitting enzyme or oxidizing agent to enhance the release of acid at a reasonable rate. 22,23 Formic acid precursors (FAP) have been used successfully in limestone formations 24 and in sandstone wells completed with gravel pack. 25 FAP offers three main benefits:…”

Section: In-situ Generated Acidsmentioning

confidence: 99%

In-Situ Acid System To Clean Up Drill-in Fluid Damage in High-Temperature Gas Wells

Alotaibi¹,

Nasr‐El‐Din²,

Moajil³

2006

Proceedings of IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition

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fax 01-972-952-9435. AbstractMany carbonate and sandstone formations are completed with horizontal and extended reach wellbores. Drill-in fluids are generally water-based muds containing a viscosifier, a fluidloss reducer, sized salts or and calcium carbonate particles. Filter cake is a major cause of restricted flow from the target zone. Effective filter cake removal during well completion is very difficult to achieve, especially in deep heterogeneous reservoirs. The obstacles encountered are the difficulty of zonal coverage of cleaning fluids with the filter cake throughout the whole interval, and controlling the rate of removal of the filter cake to ensure uniform coverage of the whole interval. The cleaning solutions can be acids, enzymes, oxidizers, chelating agents, or combinations of these materials. Enzymes are only specific for biopolymers and will not attack the calcium carbonate particles. Acids are highly reactive and corrosive fluids.A new in-situ acid system can deliver the acid to long interval wells. The treatment fluid contains an acid precursor that provides time-controlled downhole acid release. Several lab experiments were conducted to examine thermal stability of fluids at high temperatures. The kinetics of acid producing reactions were examined in detail. Modified dynamic and static HPHT fluid loss cells were used to assess the effectiveness of the system in cleaning drill-in fluid filter cake. The surface tension of the acid precursor and the spent acid was measured as a function of temperature and acid concentration.No phase separation of precipitation was noted when the precursor solution what heated to 250F for 24 hours. Unlike conventional HCl acid-based systems, the slow reaction kinetics ensures better distribution of the new fluid across long sections with minimal losses during pumping. The HPHT experiments showed a significant improvement in the efficiency of removing acid soluble portions of the filter cake. Surface tension measurements indicated that the spent acid solution had low surface tension, which will accelerate lifting the spent acid from tight formations.

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Section: In-situ Generated Acidsmentioning

confidence: 99%

In-Situ Acid System To Clean Up Drill-in Fluid Damage in High-Temperature Gas Wells

Alotaibi¹,

Nasr‐El‐Din²,

Moajil³

2006

Proceedings of IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition

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“…Much effort has been made for oil-based filter cake removal. Leschi et al and Al-Kuait et al proposed the use of organic acid precursor (OAP) and water wetting additives [40,41]. Micro-emulsion solutions formulated from alcohol and surfactants have been suggested [42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Novel Cake Washer for Removing Oil-Based Calcium Carbonate Filter Cake in Horizontal Wells

et al. 2020

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An impermeable layer “filter cake” usually forms during the overbalanced drilling technique. Even though it helps in protecting the formation from a further invasion of drilling fluids, the removal of this layer is essential for a proper cement job and to avoid any reduction in wellbore deliverability. The design of the removal process is complicated and depends on the filter cake composition and homogeneity. This paper presents an experimental evaluation on the usage of a novel cake washer (NCW) in the removal of a filter cake formed by an invert emulsion oil-based drilling fluid that contains calcium carbonate as a weighting material while drilling a horizontal reservoir. The proposed NCW is a mixture of organic acid, mutual solvent and nonionic surfactant. It is designed to enable restored wellbore permeability for a sustainable production. Since the filter cake mainly consists of the weighting material, the solubility of calcium carbonate in NCW at different ranges of temperature, duration and concentration was investigated. An actual casing joint was used to test the corrosion possibility of the treating solution. High-pressure and high-temperature (HPHT) filtration tests on ceramic discs and Berea sandstone core samples were conducted to measure the efficiency of the filter cake removal and the retained permeability. Ethylene glycol mono butyl ether (EGMBE) was used as a mutual solvent and the solubility was higher compared to when the mutual solvent was not used in the washer formulation. A significant increase in calcium carbonate dissolution with time was observed for a duration of 24 h. The solubility was found to be proportional to the concentration of NCW with optimum results of 99% removal at a temperature of around 212 °F. At those conditions, no major corrosion problems were detected. Permeability of the core retained its pristine value after the treatment.

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“…Al-Anzi et al [17] stated that the invert-emulsion filter cake can be uniformly removed using a delayed filter cake breaker. The organic acid precursor (OAP) is the main component in the delayed filter cake breaker in addition to water wetting additives [18]. Zubail et al [19] used an organic acid precursor (OAP) and a water wetting additive to remove the invert-emulsion filter cake after drilling horizontal wells in Safaniya Offshore Field in Saudi Arabia.…”

Section: Introductionmentioning

confidence: 99%

One-Stage Calcium Carbonate Oil-Based Filter Cake Removal Using a New Biodegradable Acid System

Elkatatny

2019

Sustainability

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Removal of the oil-based filter cake is a complex task especially in horizontal and multilateral wells. The presence of oil makes the removal process more challenging because the oil coats the weighting materials and prevents acid-filter cake interaction. Therefore, different additives are required to change the wettability of the filter cake to enhance the removal efficiency. This paper introduces a new biodegradable acid system (NBAS) that can efficiently remove oil-based filter cake in horizontal and multilateral wells where calcium carbonate is used as a weighting agent. The new biodegradable acid system (NBAS) consists of 50 vol.% biodegradable acid and 5 vol.% mutual solvent, and the remaining percent is deionized water. High-pressure high-temperature (HPHT) filtration experiments were performed to evaluate the filter cake removal efficiency and the retained permeability. The filtration and removal experiments were conducted using real core samples (Indiana limestone and Berea sandstone) at a temperature of 212 • F and 300 psi differential pressure. Afterward, the NBAS was evaluated by measuring physical properties and conducting corrosion, compatibility, and thermal stability studies. The obtained results showed that the NBAS was compatible and thermally stable for more than 48 h at 212 • F and 300 psi. The NBAS has a density of 1.05 g/cm 3 , viscosity of 1.47 cP, and surface tension of 32 dynes/cm at room temperature. The corrosion rate of the developed system was 0.03 lb/ft 2 , which is acceptable according to oil and gas industry best practices. Removal experiments showed that the filter cake was completely removed from the core samples. For Berea sandstone, 100% of the permeability was regained, while the retained permeability for Indiana limestone was 122.5%, confirming the complete removal of external and internal filter cake as well as core samples stimulation. The new acid system can be considered as an efficient solution for oil-based filter cake removal that is biodegradable and cost-effective, where the reservoir permeability can be regained in one-stage only.

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Delayed-Release Acid System for Cleanup of Al Khalij Horizontal Openhole Drains

Cited by 11 publications

References 5 publications

In-Situ Acid System To Clean Up Drill-in Fluid Damage in High-Temperature Gas Wells

In-Situ Acid System To Clean Up Drill-in Fluid Damage in High-Temperature Gas Wells

Novel Cake Washer for Removing Oil-Based Calcium Carbonate Filter Cake in Horizontal Wells

One-Stage Calcium Carbonate Oil-Based Filter Cake Removal Using a New Biodegradable Acid System

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