Iron Control in the Appalachian Basin

Dill, W.R.; Fredette, George

doi:10.2523/12319-ms

Cited by 3 publications

(9 citation statements)

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“…However, when the acid reacts with the formation and the pH increases, the corrosion products show a high tendency to precipitate and plug the pores. (Gougler et al 1985;Dill and Fredette 1983;Crowe 1986;Hall and Dill 1988).…”

Section: Introductionmentioning

confidence: 99%

Sodium Gluconate as a New Environmentally Friendly Iron Controlling Agent for HP/HT Acidizing Treatments

Rabie¹,

El-Din²

2015

SPE Middle East Oil &Amp; Gas Show and Conference

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Iron precipitation is a serious problem in acidizing treatments which can damage the formation permeability by restricting the flow channels. Solutions introduced in the past included the use of buffers, reducing agents, and chelating agents. Laboratory and field experiences concluded that chelating agents are the most effective remedy for controlling the iron precipitation. However, substantial limitations hinder the effectiveness and the application of several of the current chelating agents in the industry. These limitations include poor thermal stability at elevated temperatures, higher cost, low solubility in acidic medium, tendency of precipitating calcium products, and serious negative health and environmental impacts.This work introduces sodium gluconate as an efficient and environmentally friendly iron chelating agent. The chemical exhibits an excellent sequestering property for iron over a wide range of pH values, with a chelation power comparatively closer to those reported for EDTA and NTA. The salt is readily dissolved in the acids with a solubility of 600 gm/l.The objectives of this study are to: (1) investigate the ability of sodium gluconate to prevent iron precipitation at different iron loading, (2) examine the efficiency of the new chelant in hydrochloric acid solutions (5, 10, and 15 wt%) at a temperature of 200 and 250°F and chelant to iron molar ratios of 1:1, 2:1, and 4:1, and (3) determine the optimum chelant to iron molar ratio that results in the highest chelation capacity. The effectiveness of the new chemical was examined by determining the percentage increase/ reduction in core permeability.In stirred reactor experiments, iron precipitation was observed at a pH above 2 with the absence of the chelant at iron loading at 5,000 and 10,000 ppm at 77°F. The presence of Na gluconate at an equimolar ratio of the iron loading prevent the precipitation over the investigated range of iron load and temperature.Coreflood results showed that at low injection rates of 0.5 cc/min, 200°F, and 5 wt% HCl with 10,000 ppm Fe 3ϩ the core was damaged and the acid was not able to enter the core due to iron precipitation on the core inlet. At a higher injection rate (2 cc/min) the presence of 5 wt% Na-gluconate enhanced the permeability by 74% (versus 50% when no chelant was added) after injecting 0.75 PV of the acid with a load of 5,000 ppm Fe 3ϩ . At a load of 10,000 ppm of iron (III), the permeability increased to 165% compared to 70% for a controlled experiment. The results of another set of experiments at 250°F and 15 wt% HCl with a load of 10,000 ppm indicated that a 1:1 molar ratio of chelant to iron concentration is the optimum for the maximum chelation capacity compared to the results obtained for other experiments in which the molar ratio of sodium gluconate to iron was 2:1 and 4:1. These results were confirmed by fluid analysis, which showed a significant increase in both ion concentrations at this molar ratio in the effluent samples.

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Section: Introductionmentioning

confidence: 99%

Sodium Gluconate as a New Environmentally Friendly Iron Controlling Agent for HP/HT Acidizing Treatments

Rabie¹,

El-Din²

2015

SPE Middle East Oil &Amp; Gas Show and Conference

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“…The aim was to dissolve large amounts of carbonate rocks near the wellbore region to bypass the damage to the original permeability of the reservoir rock. Iron comes from many sources that may include storage and mixing tanks, mill scale in new pipelines and tubulars, and iron-minerals bearing formations (Dill et al 1983;Crowe et al 1986;Hall et al 1988). Iron comes from many sources that may include storage and mixing tanks, mill scale in new pipelines and tubulars, and iron-minerals bearing formations (Dill et al 1983;Crowe et al 1986;Hall et al 1988).…”

Section: Introductionmentioning

confidence: 99%

“…Iron precipitation is a very serious problem that can be detrimental to the success of any matrix acidizing treatment (Gougler et al 1985). Some iron compounds are soluble, others are insoluble in acids, but even the soluble compounds precipitate when the acids are spent (Dill et al 1983). Some iron compounds are soluble, others are insoluble in acids, but even the soluble compounds precipitate when the acids are spent (Dill et al 1983).…”

Section: Introductionmentioning

confidence: 99%

“…Some iron compounds are soluble, others are insoluble in acids, but even the soluble compounds precipitate when the acids are spent (Dill et al 1983). Fe 2+ ions are not a real problem in sweet environments because they remain in solution until pH of 6.5 (Dill et al 1983), however they can be easily oxidized to Fe 3+ . Fe 3+ ions start to precipitate at pH of 1 (Taylor et al 1999b).…”

Section: Introductionmentioning

confidence: 99%

“…For instance, in the case of fracturing fluids, dissolved oxygen is incompatible with formation water carrying ferrous ions. In sweet wells, sequestering agents are used frequently to address this problem (Crowe et al 1986;Dill et al 1983). Acid readily dissolves iron scale in pipes and also attacks iron-containing minerals in the formation.…”

Section: Introductionmentioning

confidence: 99%

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

2013

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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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Geochemical phenomena between Utica‐Point Pleasant shale and hydraulic fracturing fluid

2019

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This study evaluated geochemistry between the Utica-Point Pleasant shale and reservoir/hydraulic fracturing fluid mixtures under simulated reservoir conditions in a batch reactor system. Analytical techniques were utilized to monitor fluid composition with time along with pre-and post-trial shale microscopy and phase identification analyses. Formation of iron-based precipitate was evident through results from fluid and material analyses. Ferrous iron was the predominant iron form found in the aqueous phase, with oxidation to ferric iron and subsequent precipitate formation. Geochemical modeling further supported ferric iron was the favorable phase for precipitation. K E Y W O R D S crystallization (precipitation), geochemical, hydraulic fracturing, oil shale/tar sands, reaction kinetics 1 | INTRODUCTION U.S. tight oil has had a tremendous impact on stabilizing global oil prices and increasing energy security. Such light crude is recovered from low permeability rock formations, primarily shale, using unconventional methods such as horizontal drilling with hydraulic fracturing. As of March 2019, the Energy Information Association (EIA) reports approximately 60% total U.S. oil production comes from tight oil. 1 While unconventional wells have shown promise in terms of oil production, economic viability is still uncertain due to rapid production decline leading to shorter well life. Peak performance of an unconventional oil well occurs during the first quarter of production, with up to 74% production decline after 1 year. 2 Solutions explored to counteract production decline include refracturing or other enhanced oil recovery methods. Simulation studies have been developed to evaluate the effects of stimulation techniques on production to determine if profitable recovery is feasible. 3-5 Although simulation of refracturing and enhanced oil recovery methods have shown promise, these techniques do not fully account for phenomena encountered in unconventional wells. Various approaches have been utilized to mimic downhole phenomena. 6-8 An approach by Luo evaluated confinement effects on hydrocarbon bubble point. This study found octane and decane confined in nanoporous media possess two distinct bubble point temperatures, with lower/higher bubble point temperatures differing ±15 K in comparison to respective bulk properties. 6 By understanding various in-situ well phenomena, proper recovery analysis can be performed and modifications to hydraulic fracturing processes can be developed to increase well productivity and lifetime. 9 Aqueous phase chemical reactions are another key phenomenon occurring in shale reservoirs. Such reactions occur during well completion, when hydraulic fracturing fluid (HFF) mixes with rock and formation water, potentially causing precipitate formation, more commonly referred to as scale. Scales form when dissolved solid concentrations This contribution was identified by Rameshwar Srivastava (Department of Energy) as the Best Presentation in the session "New Technologies to Enhance the Productio...

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Iron Control in the Appalachian Basin

Cited by 3 publications

References 0 publications

Sodium Gluconate as a New Environmentally Friendly Iron Controlling Agent for HP/HT Acidizing Treatments

Sodium Gluconate as a New Environmentally Friendly Iron Controlling Agent for HP/HT Acidizing Treatments

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

Geochemical phenomena between Utica‐Point Pleasant shale and hydraulic fracturing fluid

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