Predicting the location of barium sulfate scale formation in production systems

2005 ◽  
Author(s):  
Ian Ralph Collins
Keyword(s):  
Barium Sulfate ◽  
Production Systems ◽  
Scale Formation

Prediction of Barium Sulfate Scale Formation in Oilfield Environment

2009 ◽  
Vol 6 (2) ◽  
pp. JAI102049
Author(s):  
S. W. Dean ◽  
Hosni M. Ezuber
Keyword(s):  
Barium Sulfate ◽  
Scale Formation

Crystal Growth and Dissolution of Barium Sulfate

1975 ◽  
Vol 15 (06) ◽  
pp. 509-516 ◽  
Author(s):  
G.H. Nancollas ◽  
S.T. Liu
Keyword(s):  
Crystal Growth ◽  
Crystal Lattice ◽  
Barium Sulfate ◽  
Scale Formation ◽  
Dissolution Process ◽  
Equilibrium Solubility ◽  
Precipitation Reactions ◽  
Solubility Products ◽  
Precipitated Phases ◽  
Made In

Abstract The kinetics of crystallization and dissolution of barium sulfate seed crystals were investigated conductimetrically. Growth is characterized by an initial surge caused by secondary nucleation, followed by a rate that is proportional to The square of the supersaturation. Studies were made using seed material of differing morphology; in all cases, the crystallization was surface controlled. A surface reaction also appears to be rate-determining for the corresponding dissolution process, but the over-all rate constant is considerably greater than that for growth. Crystallization and dissolution were studied in the presence of potential phosphonate and polyphosphate scaling inhibitors phosphonate and polyphosphate scaling inhibitors in some cases, both processes were markedly inhibited. The incorporation of the antiscalant into the developing crystals may pose problems in down-hole application. Introduction The state of knowledge of adsorption and desorption phenomena and of reactions at the solid-liquid interfaces under wellbore conditions is extremely limited. Consequently, the procedures used for eliminating scale by the chemical treatment of surface waters that are frequently injected into an oil-bearing formation are often based on empirical considerations. In the absence of knowledge of the mechanism of scale formation and its inhibition, the choice of additive is usually made on the basis of the results of spontaneous precipitation experiments made in the laboratory. precipitation experiments made in the laboratory. Although attempts are made to reproduce such experimental data, extreme sensitivity to factors such as the methods used to mix reagents, rates of stirring, and concentrations of reactants make it impossible to do so. Also, it is difficult to avoid heterogeneous nucleation in such systems, and this process also may be influenced by the presence of the additive. Interpretations of the course of the precipitation reactions solely in terms of the precipitation reactions solely in terms of the thermodynamic solubility products of the precipitating minerals also is questionable. Such precipitating minerals also is questionable. Such treatments assume that, at all stages of the scaling process, the systems are effectively at equilibrium process, the systems are effectively at equilibrium and are amenable to treatment using experimental solubility products. It has been shown that kinetic factors often are considerably more important in determining the course of a precipitation process. Thus, in the case of calcium phosphate crystal growth, an amorphous precursor is formed rapidly at the beginning of the reaction and undergoes a slow transformation to the thermodynamically stable phase, hydroxyapatite. Significant changes with phase, hydroxyapatite. Significant changes with time are observed in such factors as chemical composition, crystallinity, and the specific surface areas of the solid phases. The nature of the initially precipitated phases and the course of the subsequent precipitated phases and the course of the subsequent crystal growth reaction is markedly dependent not only on the degree of supersaturation of the solution, but also on the ionic strength of the solution and the type of neutral or inert electrolyte present. Simple equilibrium solubility studies reveal nothing of these factors that may be important in determining whether scale will form in the field. Not only is the growth of crystals important for studies of scale formation, but a knowledge of the mechanism of the reverse process, dissolution, also is essential if the results of laboratory experiments are to be used to predict the behavior in actual scaling situations. At first, the growth and dissolution of crystals may be considered to be exactly reciprocal processes. The dissolution process usually has been considered to be a simple process usually has been considered to be a simple diffusion-controlled process, with the transport of lattice ions away from the crystal surface as the slow step in the reaction. in terms of diffusion following Fick's law, the rate of reaction would be expected to be proportional to the subsaturation, mo - m, where m is the molar concentration of electrolyte in the solution and mo is the equilibrium (solubility) value. Although a number of salts follow this kinetic path, there is now appreciable evidence that the dissolution of many slightly soluble salts is controlled by a process other than film diffusion of the crystal lattice ions. Whereas scale inhibitors would be expected to have little influence on a dissolution process that depends on the diffusion of crystal lattice ions away from the surface, a surface-controlled process may be markedly retarded in their presence. SPEJ P. 509

A Study of Solubility of Strontium Sulfate

1983 ◽  
Vol 23 (02) ◽  
pp. 292-300 ◽  
Author(s):  
Donald F. Jacques ◽  
Brent I. Bourland
Keyword(s):  
Sodium Chloride ◽  
Production Systems ◽  
Scale Formation ◽  
Pressure Effects ◽  
Solubility Data ◽  
Special Equipment ◽  
Solubility Study ◽  
Strontium Sulfate ◽  
Production Wells ◽  
Oilfield Brines

Abstract This paper describes the results of a solubility study of strontium sulfate in sodium chloride brine. A predictive equation for the solubility of strontium sulfate is presented, which is useful for calculating solubility in water containing 0 to 200 g/L (0 to 200 g/dm3) sodium chloride at temperatures from 100 to 300 degrees F (38 to 149 degrees C), with pressures from 100 to 3,000 psig (689 to 20 684 kPa), and total ionic strengths of 0 to 3.43. This paper also describes the experimental technique employed and the special equipment designed for this study. Introduction Strontium sulfate scale formation has become a growing concern in oil-production systems. Until recently, the appearance of strontium in oilfield scales has been primarily in the presence of barium sulfate scale. Almost pure SrSO4 scale now is observed in several production wells around the world. The scale formation is primarily a result of subsurface commingling of waters, which results in a water supersaturated in SrSO4. The literature does not readily provide solubility data that permit prediction of SrSO4 scaling under downhole conditions. Jacques et al. presented the most recent SrSO4 solubility data in 1979. Their work presented a comprehensive literature survey, new solubility data developed in synthetic brine systems from 77 to 212 degrees F (25 to 100 degrees C), and studies of effective SrSO4 scale inhibitors. The study showed that the solubility of SrSO4 increased with increasing ionic strength and decreased with increasing temperature once 104 degrees F (40 degrees C) had been exceeded. A method of predicting SrSO4 precipitation in field brines was suggested on the assumption that solubilities based on pure sodium chloride systems were the limiting thermodynamic case. This model did not provide for pressure effects and it was limited to 212 degrees F (100 degrees C). Some work available at the time indicated slight increases in SrSO4 solubility with pressure, but the study was limited to 95 degrees F (35 degrees C) maximum and low salinity. To predict SrSO4 precipitation and scaling under downhole conditions, solubility data are needed that bracket all possible temperatures, pressures. and salinities of oilfield waters. This study reports the results of new solubility determinations developed under broader test conditions. The results then are combined with the 1979 data 4 to provide a predictive solubility model. Theory To develop data that could be used generally to predict SrSO4 solubility in most oilfield brines, the solubility of SrSO4 was studied in pure synthetic NaCl brines. The salinity, temperature, and pressure ranges used in this study were selected to encompass most oilfield conditions. Minimum Maximum Salinity, g/L, NaCl 0 200Pressure, psig (kPa) 100(689) 3,000 (20 700)Temperature, degrees F 100 (38) 300 (149)( degrees C) To develop the most useful data possible over the ranges of the three variables listed demanding the fewest possible experiments, we used the Box-Behnken experimental design as taught by DuPont. This space-filling design was followed by a second design, a 2 3 factorial, inside the first design. SPEJ P. 292^

Scale Formation of Barium Sulfate in the Piping Flow System: Mineralogy and Morphology Evaluation

2017 ◽  
Vol 23 (12) ◽  
pp. 12243-12246
Author(s):  
N Karaman ◽  
J Jamari ◽  
A. P Bayuseno ◽  
S Muryanto
Keyword(s):  
Barium Sulfate ◽  
Flow System ◽  
Scale Formation

The Kinetics of Crystallization of Scale-Forming Minerals

1974 ◽  
Vol 14 (02) ◽  
pp. 117-126 ◽  
Author(s):  
G.H. Nancollas ◽  
M.M. Reddy
Keyword(s):  
Crystal Growth ◽  
Calcium Carbonate ◽  
Barium Sulfate ◽  
Calcium Sulfate ◽  
Scale Formation ◽  
Oil Field ◽  
Carbon Dioxide Partial Pressure ◽  
Physical Factors ◽  
Temperature And Pressure ◽  
Kinetics Of

Abstract Reviewed here is the kinetics of crystal growth of sparingly soluble minerals such as calcium carbonate, calcium sulfate, and barium sulfate, which frequently cause scaling problems in oil fields. For all three electrolytes, the crystal growth is surface controlled and follows a second-order rate law with an activation energy for the growth process of 10 to 20 kcal mol(-1). The growth of calcium sulfate seeded crystal above 100 degrees C demonstrates the importance of characterizing polymorphic transformation processes. Phosphonate scale inhibitors show differing modes of Phosphonate scale inhibitors show differing modes of imbibition in systems precipitating CaCO3 and CaSO4. Introduction The formation of crystals of scale-forming, sparingly soluble minerals continues to be a very serious problem for the petroleum engineer. Scaling arises from a specific set of geological, physical, and chemical conditions. Geological factors such as ground water circulation and mineral composition may mediate in scale formation as may physical factors such as pumping rate, well pressure, and the extent of fluid addition to the oil-bearing formation. However, the principal factors regulating scale formation in the oil field are chemical and such investigations can answer many of the problems. For example, scale caused by the addition problems. For example, scale caused by the addition of surface water to an oil-bearing formation can often be eliminated by chemical treatment of the injected water. A more important scaling arises from changes in subsurface mineral solubility due to variations in temperature and pressure under down-hole conditions. The difficulties are compounded by the fact that conditions frequently encountered under down-hole conditions, notably high pressure and high temperature, cannot be readily simulated in the laboratory. Sampling of an aqueous solution brought to the surface for analysis can lead to entirely misleading results owing not only to changes in temperature and pressure, but also to the fact that the solution may be actively depositing scale minerals within the well. In addition, the possible deposition of carbonate scale is dependent possible deposition of carbonate scale is dependent upon the carbon dioxide partial pressure in contact with the solution. The minerals that appear to pose the most serious problems in oilwell scaling are the sulfates of calcium and barium, and calcium carbonate. Calcium sulfate and calcium carbonate have solubility values that decrease with increasing temperature. The higher ambient temperature in the down-hole situation will therefore encourage the formation of scale deposits of these minerals. In the case of calcium sulfate the problem is complicated by the transition between the dehydrate, hemihydrate, and anhydrite phases. These calcium sulfate polymorphs may be stable or unstable under different conditions of temperature or of ionic strength. Barium sulfate presents a particularly serious problem, since it is very insoluble and cannot be dispersed once it has deposited as scale. Numerous studies have been made of the spontaneous precipitation of sparingly soluble minerals from solutions containing concentrations of the crystal lattice ions considerably in excess of the solubility values. Attempts are usually made to use controlled methods of mixing the reagent solutions containing the lattice ions, but it is extremely difficult to obtain reproducible results from such experiments. There are probably no systems that are entirely free from foreign substances or particles that can readily act as sites for the formation of nuclei of the precipitating phase. The attainment of so-called "homogeneous" phase. The attainment of so-called "homogeneous" nucleation conditions is therefore very difficult even when extreme precautions are taken to exclude impurities and foreign particles from the solutions. Experiments are frequently conducted to determine scaling thresholds in the laboratory by mixing solutions of salts containing the lattice ions and observing the appearance of the first precipitate. Such experiments are open to the same objections as those given above, however; moreover, they are frequently carried out in such a manner as to ignore important kinetic factors in the rate of precipitation. Thermodynamic interpretations of the results assume the attainment of equilibrium and involve the thermodynamic solubility products of the precipitating minerals. precipitating minerals. SPEJ P. 117

Sign in / Sign up

Export Citation Format

Share Document