An Improved, One-Step Cleanup System for Removing Mud Damage in Horizontal Wells

Ali, Syed A.; Ahmad, Atikah bte; Rae, Phil; Gilmore, Todd Gerard

doi:10.2118/86495-ms

Cited by 11 publications

(3 citation statements)

References 5 publications

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“…Calcium carbonate filter cake can be removed by conventional methods such as the use of live acids, organic acids (Ali et al, 2004), oxidising agents (Brady et al, 2000), chelating agents , enzymes (Price-Smith et al, 1998), in-situ generated acids (Nasr-El-Din et al, 2005), or a combination of these chemicals.…”

Section: Introductionmentioning

confidence: 99%

Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent

Elkatatny¹,

Nasr‐El‐Din

2014

IJOGCT

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Chelate solutions, GLDA (pH of 3.3 to 13) and HEDTA (pH of 4 and 7) were incompatible with α-amylase over a wide range of temperatures. GLDA (pH 3.3) and HEDTA (pH 4) can be used to remove the filter cake in one step. GLDA (20 wt% in a 200 g solution and pH of 3.3) and HEDTA (20 wt% in a 200 g solution and pH 4) had 100% removal efficiency of the filter cake. The retained permeability was 110% and 106% for Berea sandstone and Indiana limestone cores, respectively when using GLDA (13.3 wt% in 300 g solution and pH of 3.3). The retained permeability was 115% and 100% for Berea sandstone and Indiana limestone cores, respectively when using HEDTA (20 wt% in 200 g solution and pH of 3.3). No core damage was observed when using GLDA and HEDTA solutions as a breaker to remove water-based filter cake. [Reference to this paper should be made as follows: Elkatatny, S.M. and Nasr-El-Din, H.A. (2014) 'Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent', Int.

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Section: Introductionmentioning

confidence: 99%

Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent

Elkatatny¹,

Nasr‐El‐Din

2014

IJOGCT

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“…Since the early 90's, a significant effort has been devoted to understanding the damage mechanisms associated with Reservoir Drill-in Fluids (RDF), and to develop breaker systems to specifically target bio-polymers and bridging agents in the RDF cake for improved wellbore clean-up (Almond et al, 1995, Burnett, 1998Zain et al, 1999;Brady et al, 2000a;Luyster et al, 2000;Brannon et al 2003;Ali et al, 2004;Al-Otaini et al, 2005;Battistel et al, 2005;Nasr-El-Din et al, 2005, 2007Siddiqui et al, 2006;Samuel et al, 2009). Open hole wellbore clean-up techniques include inorganic acids, strongly buffered acids, chelating agents, oxidizing agents, enzymes, delayed release organic acids and combinations thereof.…”

Section: Introductionmentioning

confidence: 99%

Laboratory Evaluation of RDF Breakers Under Linear and Radial Flow Conditions

Marquez

Lenz

2010

All Days

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Drilling-induced formation damage is an area of concern when it comes to wellbore productivity, particularly for highly deviated / horizontal open hole completions. A great deal of effort has been devoted to understanding the damage mechanisms associated with Reservoir Drill-in Fluids (RDF), and to develop systems to specifically target bio-polymers and bridging agents in the RDF cake for improved wellbore clean-up. Experimental techniques to evaluate the performance of RDF clean-up treatments, however, have not received much attention. Due to its simplicity, the High Temperature High Pressure (HTHP) cell has been widely adopted by the Industry as a standard method to evaluate the performance of RDF filter cake stimulation treatments, but this technique has a number of limitations in terms of the quality and reproducibility of the deposited filter cake, as well as its ability to predict flow initiation pressure and return to flow percentage after the stimulation treatment. This work compares the performance of two commercial RDF breakers in a GP application, under linear and radial flow conditions, using a HTHP cell and the Dynamic Displacement Radial Permeameter (DDRP) device described by Davidson et al. (2006). Unlike the HTHP cell, the DDRP cell can be arranged such that the RDF deposition, displacement, and stimulation stages of a horizontal Open Hole Gravel Pack (OHGP) can be simulated dynamically and sequentially, without system disruptions. The breakers evaluated are combinations of polymer-specific enzymes, chelating agents, and acid. Breaker "A" is a buffered acid system, while Breaker "B" contains a slow release acid precursor. The clean-up efficiency of each breaker, relative to a control system with no breaker, was determined as a function of flow rate using the DDRP device. These results were compared to those obtained under linear flow conditions with the HTHP cell. Significant differences were observed between the flow initiation pressure values measured with the HTHP cell and those measured with the DDRP, particularly for the system with no breaker. Differences were also observed in terms of percentage return to flow; higher percentages were consistently measured with the DDRP device. The difference between the percentage return to flow measured with the HTHP cell and the DDRP device was less than 5% for the system with no breaker, and 20% to 55% for the systems treated with the breaker solutions. In general, linear flow tests with the HTHP cell are useful as a pre-screening tool, but more sophisticated equipment such as the DDRP device can simulate downhole flow patterns and cake deposition more accurately and reproducibly. They also provide insight to important design parameters such as breaker activation time and flow rate dependencies of the clean-up treatment.

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“…4 Long horizontal and multi-lateral wells are tended to be complex which increases the challenge in cleanup techniques. 8 Current approaches introduced to remove filter cake include the use of live acids, strongly buffered organic acids, 9 chelating agents, oxidizing agents, 10 enzymes, 7,11,12 in-situ organic acids, or combinations of these chemicals. 7 Thus, it is important to clean drill-in fluid damage effectively to reach the aim of uniform removal from the entire completion interval.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of In-Situ Generated Acids for Filter-Cake Cleanup

Nasr‐El‐Din

Moajil

2007

All Days

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fax 01-972-952-9435. AbstractFilter cake removal is a difficult task, especially in horizontal and extended reach wells. Water-based drilling fluids consist of xanthan gum as a viscosifier, starch as a fluid-loss control, sized calcium carbonate or salt particles to increase the mud density. Conventional chemical means used to remove filter cake are reactive mineral acids, enzymes, chelating agents, oxidizers, or combinations of these chemicals. Controlling of the reaction rate of the cleaning fluids with the filter cake material is an essential factor that determines the efficiency of filter cake removal.This study assesses the performance of three acid precursors (esters) that produce organic acids. These precursors produce low-molecular weight organic acids that can dissolve calcium carbonate particles from the filter cake. The rate of hydrolysis of acid precursors can be adjusted to produce a predetermine acid concentration at bottom hole conditions. Enzymes, mainly α-amylase, can be added to these esters to break starch that is present in the filter cake. The slow release of these weak organic acids ensures proper and efficient removal of the filter cake.Lab studies using static HPHT filter press indicated that the three systems can remove the filter cake efficiently. The rate of hydrolysis was measured for each system, and found to be a function of temperature and type and concentration of the acid precursor. Surface tension measurements conducted for solutions of the three precursors at different temperatures highlighted low surface tension values for the spent acids, which are needed to lift the spent acid following the treatment.No phase separation or precipitation was observed when the three systems were heated at temperatures up to 250°F. Surface tension measurements indicated that the formic acid system had low surface tension, which will accelerate lifting these fluids from tight formations. Acetic and lactic acid systems had much higher surface tension, and a suitable surfactant will be needed to reduce the surface tension. The kinetic study indicated the very rapid reaction rate of the precursor of formic acid and a moderate reaction rate in the acetic acid system. The reaction rate of the precursor of lactic acid was in between the two systems and more close to the in-situ acetic acid system.HPHT experiments showed that formic acid system was very efficient at short soaking times at temperatures of 200 and 250°F. The performance of lactic acid was comparable to formic acid when the soaking time was increased from 4 to 6.75 hrs. The efficiency of acetic acid was much lower than the other two acids. Acetic acid will require much longer soaking times.

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An Improved, One-Step Cleanup System for Removing Mud Damage in Horizontal Wells

Abstract: TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMany wells are damaged in the course of drilling and workover by the use of drilling muds, drill-in fluids, and killpills that contain, amongst other things, polymeric

Cited by 11 publications

References 5 publications

Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent

Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent

Laboratory Evaluation of RDF Breakers Under Linear and Radial Flow Conditions

Evaluation of In-Situ Generated Acids for Filter-Cake Cleanup

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