Borate-Crosslinked Fluid Rheology Under Various pH, Temperature, and Shear History Conditions

Shah, Subhash; Lord, David; Rao, B. N. Malleswara

doi:10.2118/37487-ms

Cited by 9 publications

(4 citation statements)

References 14 publications

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“…However with basic chromium acetate as crosslinker, when pH was less than 5.5, the gelation time increased by the pH rise but decreased for pH values above 5.5. Shah et al (1997) were the first to investigate the shear history of borate-crosslinked fracturing fluid by fracturing fluid characterization facility. They observed that gel behavior is dependent on shear history.…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Mokhtari¹,

Özbayoğlu²

2010

Proceedings of SPE Production and Operations Conference and Exhibition

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This thesis addresses the application of xanthan/borate gel for lost circulation treatment. Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity was being recorded. The apparent viscosity was constant up to initial gelation time in which viscosity started to build up. Four parameters: initial and final gelation times as well as initial and final viscosities are defined and a correlation is derived between those parameters and four variables: polymer blended with crosslinker, pH-controller, and magnesium chloride concentration as well as temperature. These correlations can help the drilling industry to manage the lost circulation treatment job in a way to have enough time and pressure to pump the fluid and to optimize the time and quality required for final gel. The effects of those variables besides mixing time and shear history on gelation were also investigated. Temperature and pH-controller shortens initiation of gelation. Poly-cross shifts viscosity upward. Retarder postpones the final gelation time. Shear history does not affect initial gelation time and increase of mixing time reduces initial gelation time.v This thesis also investigates the rheological model behavior of this gel system before initial gelation time which is the time allowed for pumping the fluid. Shear stress was measured at 0.1,1,50, and 450 rpm besides the conventional readings.Then residual mean squares for six common rheological models were obtained.Sisko was found to be the best fitting model based on this statistical approach.Moreover a modified Bingham-plastic and low shear yield point model are suggested.

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Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Mokhtari¹,

Özbayoğlu²

2010

Proceedings of SPE Production and Operations Conference and Exhibition

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“…[20][21] Results: Prior to performing rheological characterization of fracturing fluids, measurements were made to confirm the accuracy and reproducibility of viscosities measured with the HPS slot. The result of this reproducibility test performed over seven days is shown in Figure 7.4.1.…”

Section: Procedurementioning

confidence: 99%

Section: -33mentioning

confidence: 99%

“…21 This result implies that the crosslinked fluid may exhibit ideal fluid properties under laboratory conditions, but under actual field conditions its behavior may be completely different. 20 Hence the borate crosslinked fluid rheology must be determined under conditions that closely simulate pumping environment through the wellbore and therefore, the laboratory characterization must incorporate shear history simulations prior to the viscometric measurements.Sometimes, however, it is difficult to incorporate shear history simulation in the laboratory measurements, an inexpensive alternate method could be to use the empirical correlation developed at the FFCF 22 as this correlation incorporates the effect of shear history on the viscosity. For example in a fracturing treatment, the wellbore tubing diameter and length are known from the well configuration; the friction pressure drop in the tubing is also readily available and so is the reservoir temperature.…”

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Fracturing Fluid Characterization Facility

Shah¹

2000

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Aggressive efforts were also made to effectively transfer the past research results to the industry Abstract (limit 200 words)Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures.During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled "The High Pressure Simulator" (HPS).The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of "The Well Construction Technology Center" (WCTC).This report documents the summary of the activities performed during 1992 -2000 at the FFCF Document Analysis a. DescriptionOil and Gas Industry, Natural Gas Production, Hydraulic iii DEPARTMENT OF ENERGY DISCLAIMERThis report was prepared by The University of Oklahoma (OU) as an account of work sponsored, in part, by U.S. Department of Energy (DOE) , Financial Assistance Award DE-FC21-92MC29077. Such support does not constitute an endorsement by DOE of the information contained in this report. UNIVERSITY OF OKLHAOMA DISCLAIMER "LEGAL NOTICE"This report was prepared by The University of Oklahoma as an account of work sponsored by the U.S. Department of Energy (DOE). Neither DOE members of DOE, The Board of Regents of The University of Oklahoma, nor any person acting on behalf of the aforementioned; (a) makes any warranty or representation, express or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or, (b) assumes any liability with respect to the use of, or for damages resulting form the use of any information, apparatus, method, or process disclosed in this report.iv During the contract period, based on consultation received from the Project Advisory Group (PAG) and the Technical Advisory Group (TAG), DOE/GRI periodically modified the statement of work to steer the project toward its goals and objectives....

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Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Mokhtari

Ozbayoglu

2010

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Crosslinked polymer gels have been extensively used in upstream petroleum industry for water shut-off, profile modification and hydraulic fracturing. The successful history of those applications has led to opening of a new frontier for solving one of the most severe and costly drilling problems known as lost circulation. Xanthan chains can be crosslinked by borate ions released from borax in appropriate pH conditions and consequently convert to a three-dimensional gel structure that can block thief zones. Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity had been recording. Apparent viscosity is almost constant up to initial gelation time in which viscosity starts growing up. Initial and final gelation times, initial and final viscosities are parameters that can describe the behavior of a gel system and are reported in this paper. The effects of concentrations of xanthan blended with borax, a pH-controller, and magnesium chloride as well as mixing time, shear history and temperature were investigated. Moreover empirical models are suggested for prediction of initial and final gelation times/viscosities as a function of the above-mentioned variables. Although the initial gelation time decreases when mixing periods increases, the summation of those is constant. In other words, the reaction causing gelation cannot be postponed by mixing. This is also true when the gel is at rest. On the other hand, it was observed that gels with high-shear rate history demonstrate similar initial gelation time as gels under 3 rpm steady shear. Moreover this low shear rate was found to not interfere in initial gelation time. Temperature and pH-controller reduce the time required for initiation of gelation. Magnesium chloride reduces the viscosity. Consequently the final gel is weaker and occurs in a longer time. Xanthan blended with borax contributes to the system mainly by increasing the viscosity. Finally the empirical models can be used to manage lost circulation treatment job. They help to have enough time to pump the pill with a known viscosity and wait enough on a gel with a desired quality.

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Borate-Crosslinked Fluid Rheology Under Various pH, Temperature, and Shear History Conditions

Cited by 9 publications

References 14 publications

Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Fracturing Fluid Characterization Facility

Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

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