Dynamic Scaling Evaluation in Gravel Packs Using Low-Sulphate Seawater

Shields, Robin J.; Bourne, H.M.; Vazquez, Oscar; Singleton, Michael

doi:10.2118/128002-ms

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…(5) Approach 5-Barite deposition kinetics in gravel packs (sand packs): This work was specifically designed to derive the kinetics of barite deposition in gravel packs** and the model described was used in practice to design "safe operating" regions where the gravel packs within the well would not scale up. **A gravel pack is a screen filled with coarse gravel (sand) which is designed to filter out any formation sand produced in an oil well (Shields et al, 2010). ( 6) Approach 6-Barite surface deposition using Synchrotron X-ray diffraction (XRD): This more fundamental study looked at barite deposition on metal surfaces and showed which crystal structures formed initially and over time.…”

Section: Mineral Scale Formation and Preventionmentioning

confidence: 99%

The deposition kinetics of barium sulphate scale: model development

2023

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The formation and deposition of mineral scales, such as barium sulphate (BaSO4) and calcium carbonate (CaCO3), is a common problem in many industrial and life science processes. This is caused by chemical incompatibility due either to the mixing of incompatible aqueous solutions or due to changes of the physical conditions, usually temperature and pressure. Many laboratory studies have been conducted using techniques broadly classified into batch and flowing tests to understand the reaction and mechanisms which occur in the initial stages of scale formation and its subsequent deposition on a solid surface. In this study we focused on the dynamic (kinetic) deposition of barium sulphate arising from the mixing of two incompatible brines, one containing barium (Ba2+) ions and other containing sulphate (SO42−) ions, suitably charged balanced by other inert anions and cations. The mechanism of barium sulphate (barite) deposition is often assumed to be a one-step reaction in which the ions in the bulk fluid directly deposit onto a surface. However, there is strong evidence in the literature that barium sulphate may deposit through an intermediary nanocrystalline phase which we refer to as BaSO4(aq) in this paper. This initial nucleation species or nanocrystalline material [BaSO4(aq)] may remain suspended in the aqueous system and hence may be transported through the system before it ultimately is deposited on a surface, possibly covered by a previously deposited barite coating. This does not preclude the direct deposition of barite on the surface which may indeed also occur. In this paper, we have formulated a barite formation/deposition model which includes both of these mechanisms noted above, i.e., i) barite formation in solution of a nanocrystalline precursor which may be transported and deposited at an interface and ii) the direct kinetic deposition of barite from the free ions in solution. When only the former mechanism applies (nanocrystal formation, transport and deposition) we refer to the model Model 1 and, when both mechanism occur together it is called Model 2. Although this is a fully kinetic model, it, must honour the known equilibrium state of the system in order to be fully consistent and this is demonstrated in the paper. The kinetic approach is most important in flowing conditions, since the residence time in a given part of the macroscopic system (e.g., in a pipe or duct) may be shorter that the time required to reach the full equilibrium state of the system. The reaction extent can be affected by advection, introduction of viscous dissipation forces, formation of hydrodynamic boundary layers and the mass transport in the boundary layer close to the depositing surface. In this paper, we call the latter the diffusion penetration length, denoted δ, and the relation of this quantity with the hydraulic layer is discussed. In this work, we have coupled the barium sulphate depositional model with a full computation fluid dynamics calculation (CFD) model in order to study the behaviour of this system and demonstrate the importance of non-equilibrium effects. Studied using different kinetic constants. The Navier-Stokes equations are solved to accurately model the local residence time, species transport, and calculate the hydraulic and mass transfer layers. A number of important concepts for barium sulphate kinetic deposition are established and a wide range of sensitivity calculations are performed and analysed. Geometry alteration due to flow constriction in the pipe or duct caused by the depositing scale is also an important phenomenon to consider and model in a flowing system, and this is rarely done, especially with a full kinetic deposition model. The geometry change affects both hydraulic and mass transport layers in the vicinity of the depositing surface and may often change the deposition regime in terms of the balance of dominant mechanism which apply. The change in geometry requires occasional re-gridding of the CFD calculations, which is time consuming but essential in order to study some critical effects I the system. The effect of geometry change on the local residence time is investigated through by performing a “ramping up” of the flow rate and explicitly deforming the geometry as the deposition occurs. The influence of surface roughness on the reaction rates was also studied using different kinetic constants. Our results show that in the laminar flow regime, the extent of deposition on a surface is limited by the diffusion penetration length (δ) referred to above. This means that there will be more deposits at lower flow rates, where the diffusion penetration length is larger. As the deposition reduces the flow path cross-section area near the inlet vicinity, the velocity increases. Thus, the hydraulic layer becomes smaller, resulting in a smaller diffusion penetration length, which causes the deposition location to move towards the end of the flow path, where the velocity is still smaller. The results of this study have the potential to contribute to the development of more effective strategies for preventing scaling in a wide range of industrial processes.

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Section: Mineral Scale Formation and Preventionmentioning

confidence: 99%

The deposition kinetics of barium sulphate scale: model development

2023

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“…The experimental conditions were adapted from Shields et al (2010). The test also demonstrates the antiscaling activity of the new LTSMA, even in brines with high total dissolved solids (TDS).…”

Section: Preventing Carbonate Scale Formationmentioning

confidence: 99%

Maintaining Well Productivity Through Controlling Fines Migration and Scale Formation

Stanciu

Nguyen

et al. 2015

Europec 2015

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The intrusion of formation fines and formation sand grains into the proppant pack drastically reduces the conductivity of propped fractures, which can negatively impact well production. This paper describes the development and field treatments using a new form of surface modification agent (SMA) that is a low-tackiness surface modification agent (LTSMA) that can be applied during primary hydraulic fracturing or remedial treatments of propped fractures. Studies were conducted to demonstrate the mechanisms by which this LTSMA controls migration and intrusion of formation sand and fines into the proppant pack, while inhibiting scale formation in the treated pack.Molecular modeling data on the LTSMA suggests that both the polymer backbones and the hydrophobic chains on the polymers are responsible for its reduced tackiness to the treatment equipment and significant scale inhibition ability. Once coated on the proppant as part of hydraulic fracturing treatment, or injected into the proppant pack and formation matrix surrounding the fractures, this LTSMA forms a thin film on the particulates, covering and anchoring the particulates in place. This LTSMA coating also forms a hydrophobic film on the particulate surfaces, inhibiting chemical reactions that lead to scale formation in the pack matrix and subsequent productivity losses.Laboratory experiments using packed beds of proppant, formation sand grains, and various fines were performed to simulate proppant pack conditions and formation fines before and after remedial treatments. Experimental results indicate that treatments with this particular LTSMA effectively control the migration of formation fines into proppant packs and successfully prevent the buildup of scale in various sand packs to maintain the fluid flow paths. No pressure buildup was noticed, opposed to the proppant that was not treated with the LTSMA, for which severe scaling had occurred by 24 hours, leading to an exponential increase in pressure drop across the proppant pack. Examination with scanning electron microscopy analysis clearly demonstrated that no scale was formed in the pore spaces between the treated proppant grains compared to a massive buildup of scale on the proppant particles and in their pore spaces when not coated with the LTSMA.In addition to remedial treatments, LTSMA treatment fluid can be applied while treating formations following an acidizing treatment, during treatment of formations before a high-rate water pack or frac-pack treatment, or as part of a pad fluid to treat the fracture faces before placement of proppant into a fracture and/or a screen annulus.

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Maintain Well Productivity Through Inhibiting Scale Formation and Controlling Fines Migration

Nguyen

Vasquez

Weaver

et al. 2010

SPE Asia Pacific Oil and Gas Conference and Exhibition

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Migration of fine particulates and/or scale formation is known to plug up etched channels or pore spaces in proppant packs, causing production decline in wells that have been acidized or completed with high-rate water packs or frac-packs. The removal of such damage caused by plugging is only a temporary solution if the source of the plugging material is not mitigated. This paper presents the results of a series of laboratory tests aimed at demonstrating and quantifying the performance of a treatment fluid for stabilizing formation fines, inhibiting scale formation, and keeping flow channels open through damaged proppant packs after production has been restored.Packed beds of proppant and formation sands were used to simulate frac-pack conditions before and after remedial treatments. The treatment fluid was comprised of a salt-free, aqueous-based solution containing an environmental friendly clay-swelling inhibitor and a water-based agglomerating agent (WBAA). The results show that this WBAA system is applicable to most types of formations, including sandstones, carbonates, and coals. Once injected into the proppant pack and formation matrix, WBAA forms a thin film on the particulates, covering and anchoring them in place, without plugging pore throats. This thin coating does not harden, but remains flexible, allowing the treated formation to withstand high shear stress during high production flow rates. WBAA coating forms hydrophobic film-encapsulating particulate surfaces, inhibiting chemical reactions that lead to scale formation in the pack matrix.The experimental results show that WBAA treatments effectively mitigate the buildup of scale in various sand packs and successfully control the migration of formation fines into proppant packs to maintain well production.

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Dynamic Scaling Evaluation in Gravel Packs Using Low-Sulphate Seawater

Cited by 6 publications

References 8 publications

The deposition kinetics of barium sulphate scale: model development

The deposition kinetics of barium sulphate scale: model development

Maintaining Well Productivity Through Controlling Fines Migration and Scale Formation

Maintain Well Productivity Through Inhibiting Scale Formation and Controlling Fines Migration

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