Lessons Learned from Repickling Old/Sour Gas Wells

Garzon, Francisco Orlando; Nasr‐El‐Din, Hisham A.; Al-Mutairi, Saleh Haif; Alharith, Abdullah

doi:10.2118/105633-ms

SPE Middle East Oil and Gas Show and Conference 2007

DOI: 10.2118/105633-ms

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Lessons Learned from Repickling Old/Sour Gas Wells

Francisco Orlando Garzon

Hisham A. Nasr‐El‐Din

Saleh Haif Al-Mutairi

et al.

Abstract: TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSaudi Arabia has embarked on developing its gas fields.

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Cited by 10 publications

References 30 publications

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A New Finding in the Interaction Between Chelating Agents and Carbonate Rocks During Matrix Acidizing Treatments

Assem

Nasr‐El‐Din

Wolf

2013

SPE International Symposium on Oilfield Chemistry

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During matrix acidizing, successful iron control can be critical to the success of the treatment. Iron (III) precipitation occurs when acids are spent and the pH rises above 1, which can cause severe formation damage. Chelating agents are used during these treatments to minimize iron precipitation.In this paper, we studied the effect of iron precipitation in acidizing operations. HCl solutions (5 -20 wt%) containing 5,000 to 10,000 ppm of Fe 3+ were used in these experiments. Biodegradable GLDA (glutamic-N, N-diacetic acid) was studied in the experiments. The effect of varying acid concentration and chelate-to-iron mole ratio was examined. Coreflood experiments were conducted on low permeability Indiana limestone (1 -5 md) at 200°F. The cores were scanned after treatments using a CT scanner. The core effluent samples were analyzed for total iron and calcium concentrations using ICP-ES. A calcium ion-selective electrode was used to determine the concentration of free calcium ions, i.e. calcium ions not complexed by the chelate, in the core effluent samples.Results showed that the amount of iron recovered depended on both chelate-to-iron mole ratio and the initial permeability of the cores. Calcium is chelated along with iron, which limits the effectiveness of chelating agents to control iron (III) precipitation. Chelating agents are supposed to control iron now that calcium is also chelated, this amount should be accounted for. Acid solutions should be designed considering this important finding for more successful treatments. This paper will discuss the results obtained and give recommendations to enhance the effectiveness of these chemicals in the field.

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A New Finding in the Interaction Between Chelating Agents and Carbonate Rocks During Matrix Acidizing Treatments

Assem

Nasr‐El‐Din

Wolf

2013

SPE International Symposium on Oilfield Chemistry

Self Cite

View full text Add to dashboard Cite

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"Dope-Free" Tubulars in Petroleum Well Completions

Funes¹,

Figini²,

Goretta

et al. 2013

All Days

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Dope", an inorganic compound, has been used routinely during well construction for both casing and tubing to lubricate, seal and protect against corrosion of segment-connecting threads. During the well tubular assembly a portion of the thread compound is exuded inside and outside the connection and gets access to the well fluids through the tubing and annular space. Studies presented here show that the dope forms a suspension which penetrates and damages the formation. The studies used standard fluid circulation velocities during typical completion operations. The formation damage is severe (more than 99 percent) and has been confirmed with a number of core-test experiments, presented in this work.If the well is put on injection service and in the case of workovers such as matrix stimulation treatments, the formation damage caused by pipe dope will almost guarantee operational failure. For production the issue is different and will depend on the reservoir permeability and the ability or lack thereof of the dope compound to penetrate the rock matrix or whether it will form a removable filter cake.

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Formation Damage Due To Iron Precipitation In Carbonate Rocks

2013

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Iron precipitation during matrix acidizing treatments is a well-known problem. However, extensive literature review highlighted that no systematic study was conducted to determine where this iron precipitates, the factors that affect this precipitation and the magnitude of the resulting damage. In this paper, the effect of iron precipitation in the acidizing operations is studied. HCl solutions (5 – 10 wt%) containing 5,000 to 10,000 ppm of Fe3+ were used for these experiments. The effect of varying acid concentration, initial core permeability, core length, temperature, and flow rate was studied. Coreflood experiments were conducted on 6 and 20 in. long Indiana limestone cores over a wide range of permeabilities and up to 300°F. In these experiments, 0.5 PV of acid solution was injected. The cores were scanned after treatments using a CT scanner and cut to better determine the location of iron deposition. The core effluent samples were analyzed for iron and calcium concentrations using ICP-OES. Results showed a significant amount of iron precipitated on the injection face of the cores and the sides of wormholes, i.e. where the contact occurs between the acid and the rock, producing a minimal or no gain in the final permeability, which indicated severe formation damage. The damage increased with the increase of the amount of iron in solution. At higher temperatures and flow rates, the damage was significant. Core length didn't affect the degree of damage. This paper will discuss the results obtained and give recommendations on whether to use iron control agents in the field or not.

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Lessons Learned from Repickling Old/Sour Gas Wells

Abstract: TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSaudi Arabia has embarked on developing its gas fields.

Cited by 10 publications

References 30 publications

A New Finding in the Interaction Between Chelating Agents and Carbonate Rocks During Matrix Acidizing Treatments

A New Finding in the Interaction Between Chelating Agents and Carbonate Rocks During Matrix Acidizing Treatments

"Dope-Free" Tubulars in Petroleum Well Completions

Formation Damage Due To Iron Precipitation In Carbonate Rocks

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