The origin of dolomite is a long-standing enigma in sedimentary geology. It has been proposed that microorganisms, especially anaerobic can overcome kinetic barriers to facilitate precipitation, although their specific role formation still unclear. Our experimental results demonstrate disordered be synthesized at room temperature abiotically from solutions containing polysaccharides such as carboxymethyl cellulose or agar. We propose when dissolved solution, strongly adsorbed on Ca-Mg...

Significance Magnesium-bearing carbonate minerals play critical roles in the health and function of Earth system because they constitute a significant fraction lithosphere carbon reservoir build skeletal structures for majority marine invertebrate organisms. Despite wide occurrence, high-Mg sole-Mg phases such as dolomite ([Ca,Mg]CO 3 ) magnesite (MgCO prove virtually impossible to be crystallized under ambient conditions. It has long been believed that Mg 2+ hydration is cause geological...

X-ray diffraction has been widely used in analyzing Ca-Mg carbonates. Compositions of biogenic and inorganic (Ca,Mg)CO3 crystals are often calculated by comparing their d104 values with published empirical curves. However, previous studies suggested that these curves do not apply to very high-Mg calcite disordered dolomite. Based on synthesized dolomite, a new curve between magnesian MgCO3 content the calcite-disordered dolomite solid-solution series is constructed. This consistent...

Because of its rare occurrence in modern sediments, as well the difficulty synthesizing it under low-temperature conditions laboratory, origin sedimentary dolomite has remained a long-standing enigma, often referred to “dolomite problem.” Recently, anaerobic microorganisms, such sulfate-reducing bacteria and methanogens, have been recognized for mediating precipitation. However, exact role microorganisms crystallization is still debate possible involvement fermenting not studied. In this...

Mineral solubility predictions are critical for estimating scaling risks at conditions of high temperature, pressure, and ionic strength (IS) in mixed electrolytes which occur various industrial processes. On the basis Pitzer theory, this study establishes a thermodynamic model to predict solubilities barite, calcite, gypsum, anhydrite under these extreme conditions. This combines related equilibrium constants, virial coefficients, minerals from 0 °C 250 °C, 14.7 psi 22000 psi, with up 6 mol...

Summary This work reports a reliable and systematic study of barite-nucleation kinetics in the presence scale inhibitors from 4 to 90°C at various conditions. In this study, we designed developed an apparatus nucleation barite-scale formation by monitoring change photocurrent created 5-mW, 635-nm red laser. The photodetector has wide wavelength range which sensitivity peak 960 nm. A set convex concave lenses was used control beam diameter so that it can pass through more particles increase...

A reliable anoxic plug flow reactor has been developed to study iron sulfide (FeS) precipitation kinetics, solubility, and phase transformation simultaneously. The effects of temperature (23–125 °C), ionic strength (0.00886–5.03 mol/kg), ferrous [Fe(II)] [S(-II)] concentration ratio (1:20 1:5) were studied. kinetics FeS was found be a pseudo-first-order reaction with respect Fe(II) concentration, when is significantly lower than the S(-II) concentration. can accelerated by high but not...

Additives play an important role in crystallization controls both natural and industrial processes. Due to the lack of theoretical understanding how additives work, use design various disciplines are mostly conducted empirically. This study has developed a new model predict additive impacts on based classical nucleation theory regular solution theory. The assumes that can impact nucleus partial molar volume apparent saturation status minerals. These two were parametrized be proportional...

The mechanistic modeling of mineral crystallization is essential for the understanding and control many natural industrial processes. In past century, mechanisms models have been proposed to explain observations in different stages. However, most only focus on a certain step or mechanism (e.g., nucleation, aggregation) lack comprehensive view. Incorporating aggregation, surface reaction together, this study developed an analytical two-stage model simulate particle size number concentration...

Summary Barite (BaSO4) is one of the common scales in oil-and-gas production. Extensive work has been conducted to study barite nucleation and inhibition at temperatures below 100°C. However, with advance deepwater exploration production (E&P) which can encounter high-temperature (HT) conditions, a better understanding barite-scaling risk HT (e.g., > 150°C) becomes essential. In this paper, systematic was explore kinetics from 70 200°C synthetic brines containing phosphonate (0–10...

Abstract Scale formation that can hinder continuous oil production is a serious problem in oilfield. Among all common scales, barite and calcite are two of the most important scales. inhibitors have been widely added to prolong induction time This study evaluates methods previous inhibition models measure predict scale presence phosphonate polymer under brine conditions. Turbidity measurement with laser light was used accurately quickly time, good reproducibility be achieved between...

Abstract A correlation between methanogenesis and dolomite formation has been reported; however, the mechanism underlying this association is not fully understood. In study, we conducted forced carbonate precipitation experiments at room temperature in calcite-seeded Ca/Mg solutions containing either purified non-living biomass or bound extracellular polymeric substances (EPS) of methanogen Methanosarcina barkeri. Purified EPS was used so as to avoid possible influence complex components...

How dolomite [CaMg(CO3)2] forms is still underdetermined, despite over a century of efforts. Challenges to synthesizing at low temperatures have hindered our understanding sedimentary formation. Unlike calcium, magnesium's high affinity toward water results in kinetic barriers from hydration shells that prevent anhydrous Ca-Mg carbonate growth. Previous synthesis studies show adding low-dielectric-constant materials, such as dioxane, dissolved sulfide, and silica, can catalyze the formation...

Abstract Ferrous iron (Fe2+) is one of the most common cations existing in oil and gas production water. Most Fe2+ ions come from dissolution siderite reservoir corrosion steel pipes. Compared to Ca2+ Mg2+, has a higher complex stability constant with some inhibitor function groups like phosphonate carboxyl due its transition metal structure. Therefore, understanding influence on inhibitors important enhance inhibition performance. Work still remain be done understand effect scale...

Abstract Mineral scale formation can lead to the blockage and shutdown of production wells in oil gas industry. Large amounts inhibitors are added mitigate losses due such mineral formation. Both insufficient excessive inhibitor additions cause unnecessary expenses. Because inhibition mechanisms poorly understood, current models do not predict accurately minimum effective dosage (MED) required for different inhibitors, temperatures, times over wide ranges. Using a new approach, this paper...

Calcite and barite are two of the most common scale minerals that occur in various geochemical industrial processes. Their solubility predictions at extreme conditions (e.g., up to 250 °C 1500 bar) presence mixed electrolytes hindered by lack experimental data thermodynamic model. In this study, calcite high Na2SO4 (i.e., 0.0407 m Na2SO4) a synthetic brine bar were measured using our high-temperature high-pressure geothermal apparatus. Using set other from thorough literature review,...

Abstract Deep water oil and gas production is playing an important role in global energy support. With the advancement of deep offshore recent years, there are more chances encountering with extreme conditions high temperature (up to 250 °C), pressure 1,500 bars) TDS halite saturated salinity) presence mixed electrolytes. Scale control such environment requires accurate prediction scale formation tendency. However, most previous models not capable predicting mineral solubilities over wide...

Summary As the oil and gas industry is making firm strides in deepwater shale exploration development, possible thermal degradation of scale-inhibitor molecules poses a great challenge for scaling control flow assurance high-temperature reservoirs. Although extensive research has been conducted to test stability scale inhibitors, little work devoted study thermodynamics/kinetics inhibitors. In this work, novel efficient testing approach based on inhibition kinetics developed successfully...