The Design of Polymer and Phosphonate Scale Inhibitor Precipitation Treatments and the Importance of Precipitate Solubility in Extending Squeeze Lifetime

Jordan, Myles Martin; Sorbie, K.S.; Chen, P.; Armitage, P.; Hammond, P.; Taylor, K.

doi:10.2523/37275-ms

Cited by 8 publications

(10 citation statements)

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“…Again, pure precipitation is characterized by a flat profile in which the [SI] is a function only of the solubility of the SI_Ca n complex (described by the solubility product, K sp ). The adsorption only is characterized by the shape of the isotherm and this has been extensively studied previously (Myers et al, 1985;Hong and Shuler, 1988;Sorbie et al, 1991aSorbie et al, , 1991bSorbie et al, , 1992Jordan et al, 1997;Yuan et al, 1993Yuan et al, , 1994. The equilibrium coupled adsorption/precipitation profile is interesting in that we can differentiate three distinct regions as follows: (a) the initial part dominate by adsorption and excess SI (the early spike); (b) the flat middle plateau which is clearly dominated by precipitation/dissolution, and (c) the later tail which is adsorption dominated and where the dissolution process is complete.…”

Section: Field Sensitivity Study Using the Dynamic  Transport Modelmentioning

confidence: 99%

“…Adsorption/desorption refers to the retention mechanism where SI is physically or chemically adsorbed onto the mineral surface of the porous medium and is described mathematically by an adsorption isotherm, (C) (Hong and Shuler, 1988;Sorbie et al, 1991Sorbie et al, , 1992. Precipitation/dissolution refers to the mechanism where SI precipitates or "phase separates" and this particulate or flocculated "precipitate" is retained within the porous medium (Yuan et al, 1993a;Malandrino et al, 1995;Hen et al, 1995;Jordan et al, 1997;Bezzera et al, 1999). This process may be described by a solubility product (K sp ) or some other related model and is denoted  in this work (see Paper I; Sorbie 2010).…”

Section: Introductionmentioning

confidence: 99%

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A General Coupled Kinetic Adsorption/Precipitation Transport Model for Scale Inhibitor Retention in Porous Media: II. Sensitivity Calculations and Field Predictions

Vazquez

Mackay

2010

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This paper describes the application of a generalised kinetic adsorption/precipitation () model for scale inhibitor (SI) retention and transport in porous media. The context of this study along with the chemistry and mathematics of the model itself are described in detail in the related Paper I (SPE 130702). Here, we describe a wide range of sensitivity calculations using this model which illustrate both (i) the consequences of this model in laboratory core floods, and (ii) the field predictions which results from various assumptions about field adsorption/precipitation processes. To our knowledge, this is the first time that such a dynamic coupled model has been deployed in this way to scale inhibitor transport modeling.This model can describe any combination of retention mechanisms (adsorption and precipitation) in either equilibrium or under dynamic (non-equilibrium).conditions. The calculations presented here also clarify the roles of adsorption and precipitation mechanisms and how they affect field squeeze return curves. These results (and related experimental work, Kahrwad et al, 2009) show that precipitation is a more important process at higher SI concentrations going over to pure adsorption at lower concentrations. These modeling results indicate how we may then exploit the roles of each of these different mechanisms in the high SI and low SI regimes. Simulations of the type presented here can also help to provide the "target properties" for SI systems (adsorption, precipitation and coupled adsorption/precipitation) of the future.This generalized model formulation also unifies the various approaches by different "schools of thought" by developing a scheme which can model any processes as appropriate. We believe that that this work resolves the controversy between adsorption vs. precipitation as the main mechanism of SI retention and replaces it with a clear generalised consistent model which may describe when (i) pure adsorption or (ii) coupled adsorption/precipitation occurs.

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Section: Field Sensitivity Study Using the Dynamic  Transport Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A General Coupled Kinetic Adsorption/Precipitation Transport Model for Scale Inhibitor Retention in Porous Media: II. Sensitivity Calculations and Field Predictions

Vazquez

Mackay

2010

All Days

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“…Nomenclature a is a constant used in phosphonate speciation constant b is a constant used to empirically represent the electrostatic effect of phosphonate speciation constant q reactant ion is the charge on the phosphonate reactant species K apparent is the apparent equilibrium constant for polymer K intrinsic is the intrinsic equilibrium constant for polymer z is the charge on the proton, +1 Z is the charge on the polymer b elec is an electrostatic work function that accounts for the increasing resistance of ionization due to the charge on the inhibitor and the effect of ionic strength. θ u is the dissociation fraction of the polymer C is the bulk concentration of the inhibitor (mg/L) at a given time (t, sec) k mass transfer (cm/sec) is the mass transfer coefficient SSA solid is the solid surface area (assumes 10,000 cm 2 /g) P solid is the solid density (≅ 2.5 g/cm 3 ) θ is the porosity of the formation (≅ 0.1−0.2) C eq is the solubility of the Ca-Phn salt (mg/L) k is the first order rate constant k 1 , k 2 , and k 3 1 Amorphous phase is the initial precipitate, the aged phase is the low solubility phase that was developed after washing the metal phosphonate salt with a large volume of synthetic brine by filtration, and the crystalline phase is the low solubility material that was developed from the amorphous material after washing the metal-phosphonate salt with a large volume of brine by filtration and the crystalinity of the solid has been confirmed with XRD analyses. 2 The solubility is estimated at 70 ºC, 75,490 mg/L TDS, 4,000 mg/L Ca, and pH 5.5.…”

Section: Acknowledgementmentioning

confidence: 99%

“…2 The solubility is estimated at 70 ºC, 75,490 mg/L TDS, 4,000 mg/L Ca, and pH 5.5. 3 The solubility is estimated at 70 C, 75,490 mg/L TDS, 40 mg/L Fe, and pH 5.5. c. d. b. Figure 7.…”

Section: Acknowledgementmentioning

confidence: 99%

“…There are several parts to understanding and optimizing, in a predictable manner, inhibitor squeeze designs. However, most of the previous efforts have been focused on describing what happens and when to re-squeeze [1][2][3] . There has been virtually no work done on the initial interaction of inhibitors with core materials in a descriptive manner that can be used for engineering design and improvement.…”

Section: Introductionmentioning

confidence: 99%

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A New Approach to Inhibitor Squeeze Design

Kan

Al-Thubaiti

et al. 2003

International Symposium on Oilfield Chemistry

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOil field scale treatments can become more difficult when working with deeper non-conventional wells. Inhibitor squeeze is generally the most efficient scale treatment technology. However, inhibitor squeeze treatment is based more on experiences than mechanistic understanding of how the chemical interacts with formation rock and how it flows back.Better mechanistic understanding of the phosphonate/rock interaction is needed to derive innovative squeeze treatment for newer non-conventional wells. Significant progress has been made toward developing a quantitative understanding of the inhibitor/rock interaction, kinetics, stoichiometry, and equilibrium as inhibitors are injected into a formation and allowed to flow back. Four common oil field inhibitors (three phosphonates and one polyacrylate) are compared. In addition to calcite (CaCO 3 ) in the reservoir rock, at least three phosphonate phases appear to be important, a low Ca and a high Ca amorphous Ca-P salts and a crystalline Ca-P salt, where "P" refers to a phosphonate molecule. The inhibitor/rock interaction follows four sequential reactions: (1) Limited acid attack of calcite; (2) Formation of a monomolecular coverage of phosphonate; (3) Reduction of further calcite dissolution due to surface poisoning by the Ca-P coating; (4) Precipitation of Ca-P solid with either low Ca or high Ca stoichiometry. Quantitative relationships between type of inhibitors, inhibitor concentration and acidity, kinetics of calcite dissolution and calcium-phosphonate precipitation are developed for the first time using a rule-based automatic approach. Consequences of the observations on squeeze design and scale inhibition will be discussed.

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