Effect of Synthesis Parameters on the Properties of Calcium Phosphonate Precipitates

Browning, Frank; Fogler, H. Scott

doi:10.1021/la00010a082

Cited by 31 publications

(27 citation statements)

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“…The range of N t values for DETPMP is in excellent agreement with similar work by Oddo and Thomson (1990), who reported N t values of 3 and 3.5 (in the presence of only DETPMP and Ca 2ϩ ) at pH levels of 4.7 and 5.0 respectively, at 70°C. In our previous studies, in the presence of only Ca 2ϩ , it was found that DETPMP can complex a maximum of 5 divalent cations per molecule at a higher pH of 12 (Shaw et al, 2012c;Shaw andSorbie, 2013a, 2013c), which is supported by other scientific literature (Browning and Fogler, 1995). The maximum number of moles of M 2ϩ (N t,max ) can only be complexed by the DETPMP at high pH, e.g.…”

Section: Resultssupporting

confidence: 57%

“…no Mg 2ϩ was present) was investigated in a similar way (Shaw, 2012;Shaw et al, 2012c;Shaw andSorbie, 2013a, 2013c). Similar work has also been performed by other researchers, testing DETPMP and HEDP in the presence of only Ca 2ϩ (Oddo and Tomson, 1990;Browning and Fogler, 1995). In the current work, a simple binding model describing the formation of the mixed complex, SI_ Ca N1 _Mg N2 is proposed, which also describes the precipitation process.…”

Section: Introductionmentioning

confidence: 53%

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Structure, Stoichiometry, and Modelling of Mixed Calcium Magnesium Phosphonate Scale Inhibitor Complexes for Application in Precipitation Squeeze Processes

Shaw

Sorbie²

2014

SPE International Oilfield Scale Conference and Exhibition

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In this paper, the properties of precipitated "mixed" calcium and magnesium phosphonate scale inhibitor (SI) complexes formed by 9 common phosphonate species are investigated. These complexes are of the form SI_ Ca Nl _Mg N2 where the stoichiometry (Ca 2ϩ /SI and Mg 2ϩ /SI molar ratios, i.e. N 1 and N 2 ) in various precipitates are established experimentally, and the effect of solution pH on the stoichiometry is determined. Static precipitation tests were performed varying the amounts of Ca 2ϩ and Mg 2ϩ present in the system (at a constant ionic strength), at test temperatures ranging from 20°C to 95°C, at a fixed [SI] ϭ 2, 000ppm. The stoichiometries of the solid precipitates were determined by assaying for Ca 2ϩ , Mg 2ϩ , and P in the supernatant liquid, under each test condition, by ICP spectroscopy. It is shown experimentally that, for all 9 phosphonates tested, these stoichiometries (i.e. N 1 and N 2 in SI_ Ca N1 _Mg N2 ) depend on (i) the nature of the SI (i.e. M 2ϩ binding sites per molecule); (ii) solution pH, which affects the speciation of the SI; (iii) the relative magnitude of the SI binding constants to Ca 2ϩ and Mg 2ϩ at the test pH (K b1 and K b2 , respectively); and (iv) the solution molar ratio of Mg 2ϩ /Ca 2ϩ . It is found that, as pH increases, the combined molar ratio of Ca 2ϩ and Mg 2ϩ to SI, i.e. N t ϭ N 1 ϩ N 2 in the complex, increases up to a theoretical maximum, N t,max , depending on the chemical structure of the phosphonate (corroborating earlier work, SPE 155114, SPE 164051). In addition, the precipitation behaviour of the various compounds is modelled theoretically by developing and solving a set of simplified equilibrium equations. Very good agreement is seen between the modelling and experimental results. Such models can be used directly in the simulation of field phosphonate precipitation squeeze treatments in order to design and optimize squeeze lifetimes.

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Section: Resultssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 53%

Structure, Stoichiometry, and Modelling of Mixed Calcium Magnesium Phosphonate Scale Inhibitor Complexes for Application in Precipitation Squeeze Processes

Shaw

Sorbie²

2014

SPE International Oilfield Scale Conference and Exhibition

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“…In some cases, [SI] may also be assayed over time in addition to IE -these experiments are referred to as SI consumption tests (Shaw, 2012;Shaw and Sorbie, 2013c). In this work, all tests were conducted at pH 5.5, taking this as a "typical" reservoir pH; pH is an important variable since it affects the speciation of SIs in aqueous solution (Browning and Fogler, 1995;Oddo and Tomson, 1990;Shaw and Sorbie, 2012, 2013a, 2013d, 2014a, 2014cStone et al, 2002). In all static IE tests described in this paper, Nelson Forties formation water (FW which has a [Ba 2ϩ ] ϭ 269ppm) was used, which (with North Sea seawater, NSSW) gives a moderately severe scaling brine mixture.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Properties of Phosphonate and Polymeric Scale Inhibitor Blends for Barium Sulphate Scale Inhibition

Shaw

Sorbie²

2014

SPE International Oilfield Scale Conference and Exhibition

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Barium sulphate is one of the most difficult types of scale to inhibit in oil and gas production systems, due to its physical hardness and its chemical and thermal stability. Barium sulphate is most commonly inhibited using either phosphonate or polymeric scale inhibitors (SIs) deployed at sub-stoichiometric concentrations. What is less well known in the oil industry is the effect of using combinations of two (or more) SIs synergistically for enhanced scale inhibition performance. A positive "synergistic" effect would be where, for example, 5ppm of A ϩ 5ppm of B performed better than 10ppm of either A or B. In this paper, a series of static barium sulphate inhibition efficiency (IE) test results are presented, in which a series of pairs of SIs have been tested to determine their synergistic properties at pH 5.5 and 95°C. Polymers can be blended with phosphonates, or alternatively pairs of phosphonates or polymers may be applied. In all cases, the synergistic IE is compared with the IE of each SI tested independently at the mass dosage (i.e. the same concentration in mg/L or ppm). Each separate single SI used in the work has been tested previously for barium sulphate IE at pH 5.5, 95°C in order to determine the minimum inhibitor concentration (MIC) for each species (Shaw et al, 2012a(Shaw et al, , 2012b. Previously, 9 phosphonate and 9 polymeric SIs have been tested individually and, in this work, 34 SI combinations have been tested to examine their synergistic properties. The MICs of the synergistic blends are compared with the normal MICs of the individual SIs. Surprisingly, in most cases, the IE of the blends is usually higher over the range of SI concentrations tested (i.e. the MIC of the blend is lower), compared to that of each SI tested separately. Certain "pairs" of SIs used together yield a significantly beneficial effect, e.g. DETPMP and HMTPMP. Some mechanistic reasons why these synergistic pairs work particularly well are suggested.

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“…The deployment of scale inhibitors using precipitation squeeze technique has proven to be an effective method to retain scale inhibitors in oilfield for inorganic scale control application (Browning and Fogler 1995). In the precipitation squeeze treatment technique, scale inhibitors are injected into the formation, after which the reservoir is shut in for a period of time.…”

Section: Introductionmentioning

confidence: 99%

Study of Scale Inhibitor Reactions in Precipitation Squeeze Treatments

Tantayakom¹,

Fogler

Chavadej

2005

Proceedings of SPE International Symposium on Oilfield Chemistry

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOne of the most effective methods used in oilfield operations to prevent or limit scale formation is the use of precipitation squeeze treatments. A fundamental understanding of scale inhibitor precipitation is important in designing squeeze treatments in oilfield. Diethylentrilopentrakis (methylenephosphonic acid) (DTPMP) and Aminotri (methylenephosphonic acid) (ATMP), two scale inhibitors used in the petroleum industry were used as model inhibitors in this study. Inhibitor concentration, solution pH and the presence of salts in the produce fluids were found to have a significant impact on the placement of scale inhibitor and result in the formation of precipitates with markedly different properties. The amount of inhibitor precipitated decreases with the addition of Mg suggesting that the presence of Mg decreases the effectiveness of Ca-Inhibitor precipitation. A model of induction time was applied to inhibitor precipitation. Long induction times allow transport of the inhibitor fluids without inhibitor precipitation and damage to near-wellbore regions. The competitive reaction among the soluble salts in the formation water with the scale inhibitor was found to delay the precipitation rate of scale inhibitors. The nucleation kinetics of Ca-ATMP is accurately described by classical nucleation theory. The presence of different salts such as LiCl, NaCl, KCl and MgCl 2 in solution was found to increase the surface free energies, thereby delaying the inhibitor nucleation and growth.

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Effect of Synthesis Parameters on the Properties of Calcium Phosphonate Precipitates

Cited by 31 publications

References 0 publications

Structure, Stoichiometry, and Modelling of Mixed Calcium Magnesium Phosphonate Scale Inhibitor Complexes for Application in Precipitation Squeeze Processes

Structure, Stoichiometry, and Modelling of Mixed Calcium Magnesium Phosphonate Scale Inhibitor Complexes for Application in Precipitation Squeeze Processes

Synergistic Properties of Phosphonate and Polymeric Scale Inhibitor Blends for Barium Sulphate Scale Inhibition

Study of Scale Inhibitor Reactions in Precipitation Squeeze Treatments

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