Optimum Injection Rate of A New Chelate That Can Be Used To Stimulate Carbonate Reservoirs

Mahmoud, Mohamed; Nasr‐El‐Din, Hisham A.; Wolf, Corine A. de; LePage, James N.

doi:10.2118/133497-ms

Cited by 17 publications

(9 citation statements)

References 31 publications

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“…The chelating agents were EDTA, HEDTA, and GLDA. GLDA is a newly introduced chelating agents, it was effective in stimulating calcite cores (Mahmoud et al 2010a). Those fluids will be used at pH values of 11 and 4 using Berea and Bandera sandstone cores at 300 o F. Therefore, the objectives of this study are to: (1) determine the compatibility of EDTA, HEDTA, and GLDA with both Berea and Bandera sandstone cores at pH of 11, (2) Determine the compatibility of HEDTA and GLDA at pH of 4 with both Berea and Bandera cores, and (3) Indentify the best chelating agent that can be used to stimulate both Berea and Bandera sandstone core at pH values of 11, and 4.…”

Section: Introductionmentioning

confidence: 99%

Novel Environmentally Friendly Fluids to Remove Carbonate Minerals from Deep Sandstone Formations

2011

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Carbonate minerals are present in sandstone formations. These minerals are either introduced to the formation during drilling/completion operations or naturally present in the rock. There is a need to remove these carbonates to enhance well performance. This especially true if there is a need to use HF-based fluids to prevent the precipitation of calcium and magnesium fluorides.In this study, we introduced GLDA (L-glutamic acid-N,N-diaceticacid) a new environmentally friendly chelate to remove carbonate minerals from sandstone formations. We also compared its performance with available chelates like EDTA (ethylenediaminetetraaceticacid) and HEDTA (hydroxyethylenediaminetriaceticacid). Berea (5 wt% clays) and Bandera (11 wt% clays) sandstone cores were used in the coreflood experiments. The concentration of the chelates used was 0.6M at pH values of 11 and 4. The coreflood experiments were run at a flow rate of 5 cm 3 /min and 300 o F.Coreflood experiments showed that at high pH values (pH =11) GLDA, HEDTA, and EDTA were almost the same in increasing the permeability of both Berea and Bandera sandstone cores. GLDA, HEDTA, and EDTA were compatible with Bandera sandstone cores. The weight loss from the core was highest in case of HEDTA and lowest in case of GLDA at pH 11. At pH 4, 0.6M-GLDA performed better than 0.6M HEDTA in the coreflood experiments. The permeability ratio (final/initial) for Bandera sandstone cores was 2 in the case of GLDA and 1.2 in the case of HEDTA at pH of 4, and 300 o F. At pH 11, HEDTA, EDTA, and GLDA almost were the same in enhancing the permeability of the Bandera sandstone cores. At pH value of 4, GLDA gave the best results in Berea and Bandera sandstone cores.

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Section: Introductionmentioning

confidence: 99%

Novel Environmentally Friendly Fluids to Remove Carbonate Minerals from Deep Sandstone Formations

2011

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“…EDTA and HEDTA chelating agents' structure that will be used in this study are shown in Fig. Mahmoud et al (2011aMahmoud et al ( , 2011bMahmoud et al ( , 2011cMahmoud et al ( , 2011dMahmoud et al ( , and 2012 investigated the use of different chelating agents as stand-alone stimulation fluids in carbonate and sandstone formations at high temperatures as alternatives to conventional acids such as HCl and organic acids. Fig.…”

Section: Chelating Agentsmentioning

confidence: 99%

A New Chemical EOR for Sandstone and Carbonate Reservoirs

Mahmoud

Abdelgawad

2014

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Recently the low salinity water flooding has been introduced as an effective enhanced oil recovery method in sandstone and carbonate reservoirs. The recovery mechanism using low salinity water injection is still debatable. The suggested mechanisms are: wettability alteration, interfacial tension reduction, and rock dissolution. In this paper we will introduce a new chemical EOR method for sandstone and carbonate reservoirs that will give better recovery than the low salinity water injection without treating sea water. The new chemical EOR fluid can be used at low concentrations and can be added to the raw sea water without treatment or softening. Low salinity water was proved to cause damage to the reservoir because of the calcium sulfate scale formation during the flooding process. These chemicals are chelating agents at high pH value such as EDTA and HEDTA.Coreflood experiments and zeta potential measurements were performed using EDTA and HEDA chelating agents added to the sea water and injected into Berea sandstone and Indiana limestone cores of 6 in. length and 1.5 in. diameter. The coreflooding experiments were performed at 100 o C and high pressure. The newly introduced EOR method does not cause sulfate precipitation and the core permeability was not affected. The coreflooding effluent was analyzed for cations using the ICP to explain the recovery mechanism. The effect of iron minerals on the rock surface charge will be investigated through the measurements of zeta potential for different rocks containing different iron minerals.The oil recovery increase in both sandstone and carbonate cores was up to 23% of the initial oil in place using the new fluid system. The rock dissolution, interfacial tension (IFT) reduction, and wettability alteration were the recovery mechanism in order. The IFT reduction was due to the high pH of the newly introduced fluid. The existence of iron minerals in sandstone rocks increase the positive values of zeta potential and this will change the rock towards more oil wet. Adding EDTA and HEDTA chelating agents at high pH to the sandstone rocks containing iron changed zeta potential to be negative in which changing the rock towards more water wet.

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“…They were followed by Frenier and co-workers (2001Frenier and co-workers ( , 2003Frenier and co-workers ( , 2004 who introduced HEDTA. Mahmoud et al used GLDA to stimulate carbonate (LePage et al 2011;Mahmoud et al 2011aMahmoud et al , 2011b and sandstone formations (Mahmoud et al 2015) to remove carbonates and oxides minerals. Reyes et al (2013) examined a new chelant.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Methods to Improve Matrix Stimulation of Horizontal Carbonate Wellbores

Nasr‐El‐Din

Shedd²,

Germack³

et al. 2015

Day 2 Tue, November 10, 2015

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Acid stimulation of horizontal wellbores in high temperature and/or low permeability formations is complicated due to the need to balance acid reaction rates with the rate of formation penetration. At high bottom hole temperatures, uncontrolled acid spending rates result in inefficient or even damaging treatments. It is advantageous to add materials which slow the reaction of HCl or use alternative acids which are useful as alternative stimulation fluids, such as organic acids and chelants due to their inherently lower reaction rates. The slower reaction rate with carbonate minerals allows for optimal wormhole growth at the limited rates available in long horizontals. This study investigates the complementary use of acid or chelant systems together with a microemulsion delivery system to achieve the desired performance. These delivery systems can significantly increase the efficiency of HCl and chelant stimulation treatments of low-permeability carbonates by optimizing diffusivity and minimizing pressure to cleanup.Horizontal core flow experiments were conducted by injecting solutions of 15 wt% HCl and 10 -20 wt% alternative acids through low permeability (Ͻ 10 md) limestone cores. High permeability cores were also investigated by injecting 15 wt% HCl through high permeability (150 -200 md) Indiana limestone cores. These experiments were conducted with and without the addition of a microemulsion additive and at core injection rates from 0.2 -20 cm 3 /min corresponding to 0.25 to 5 BPM per 100 ft of a horizontal wellbore.Significant performance advantages were found with the addition of the microemulsion delivery system. The treatment volume required for wormholes to propagate the length of the test core was reduced at all flow rates at or above the optimum rate. Core penetration was more efficient when using the microemulsion, without an increase in pumping pressure. Initiation and extension of wormholes was improved, as compared to the experiments without the microemulsion, in which more conical wormholes tended to form at the inlet face. The reduction in treatment volume necessary to reach breakthrough with the microemulsion present also suggested a more efficient treatment.The complementary use of a microemulsion delivery system with acids and chelants has been shown to enhance acid stimulation treatment potential in long horizontal wellbores with high temperature or low permeability formations. This system can be used to optimize wormhole penetration while maintaining an optimum injection rate across long horizontal intervals where the maximum achievable injection rate is relatively low.

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Optimum Injection Rate of A New Chelate That Can Be Used To Stimulate Carbonate Reservoirs

Cited by 17 publications

References 31 publications

Novel Environmentally Friendly Fluids to Remove Carbonate Minerals from Deep Sandstone Formations

Novel Environmentally Friendly Fluids to Remove Carbonate Minerals from Deep Sandstone Formations

A New Chemical EOR for Sandstone and Carbonate Reservoirs

Evaluation of Methods to Improve Matrix Stimulation of Horizontal Carbonate Wellbores

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