Barite Scaling Potential Modelled for Fractured-Porous Geothermal Reservoirs

Abstract

Barite scalings are a common cause of permanent formation damage to deep geothermal reservoirs. Well injectivity can be impaired because the ooling of saline fluids reduces the solubility of barite, and the continuous re-injection of supersaturated fluids forces barite to precipitate in the host rock. Stimulated reservoirs in the Upper Rhine Graben often have multiple relevant flow paths in the porous matrix and fracture zones, sometimes spanning multiple stratigraphical units to achieve the economically necessary injectivity. While the influence of barite scaling on injectivity has been investigated for purely porous media, the role of fractures within reservoirs consisting of both fractured and porous sections is still not well understood. Here, we present hydro-chemical simulations of a dual-layer geothermal reservoir to study the long-term impact of barite scale formation on well injectivity. Our results show that, compared to purely porous reservoirs, fractured porous reservoirs have a significantly reduced scaling risk by up to 50%, depending on the flow rate ratio of fractures. Injectivity loss is doubled, however, if the amount of active fractures is increased by one order of magnitude, while the mean fracture aperture is decreased, provided the fractured aquifer dictates the injection rate. We conclude that fractured, and especially hydraulically stimulated, reservoirs are generally less affected by barite scaling and that large, but few, fractures are favourable. We present a scaling score for fractured-porous reservoirs, which is composed of easily derivable quantities such as the radial equilibrium length and precipitation potential. This score is suggested for use approximating the scaling potential and its impact on injectivity of a fractured-porous reservoir for geothermal exploitation.

Mineral and Fluid Transformation of Hydraulically Fractured Shale: Case Study of Caney Shale in Southern Oklahoma

“…The decline, however, could be the result of formation of Sr-based minerals such as celestite, which readily precipitate in the presence of sulfates, albeit in trace quantities for this reaction since the mineral was not detected in XRD analysis. Celestite is known to cause permeability impairment in reservoirs (Mackay 2003;Shojaee et al 2023;Tranter et al 2021).…”

Capturing the Dynamic Processes of Porosity Clogging

“…Understanding mineral precipitation induced porosity clogging and quantifying its impact on transport and mechanical properties of porous media is important for several energy‐related subsurface systems, including CO 2 sequestration (Brunet et al., 2013; Masoudi et al., 2021; Noiriel et al., 2012; Rathnaweera et al., 2016; Wasch et al., 2013), oil recovery (Schovsbo et al., 2016), geothermal reservoirs (Tranter et al., 2021; Wagner et al., 2005), or deep geological disposal of radioactive waste (De Windt & Spycher, 2019; Fukatsu et al., 2017; Marty et al., 2009; Mon et al., 2017; Samper et al., 2016; Shao et al., 2013; Steefel & Lichtner, 1998; Trinchero et al., 2020; Xie et al., 2022). At the interfaces of multi‐barrier systems, chemical and thermal gradients promote mineral precipitation reactions in porous media, altering pore space morphology (pore size, shapes, and connectivity) and porosity of the system.…”

“…The accompanying reorganization of the flow field can significantly reduce effective transport properties of the porous media (Chagneau et al., 2015; Hommel et al., 2018; Poonoosamy et al., 2015; Putnis, 2015; Rajyaguru, 2018). As a result, the efficient extraction can be considerably reduced, posing a potential risk on contamination for the surrounding and groundwater resources (De Windt & Spycher, 2019; Marty et al., 2009; Poonoosamy et al., 2015; Seigneur et al., 2019; Tranter et al., 2021; Trinchero et al., 2020; Wagner et al., 2005; Wasch et al., 2013; Xie et al., 2022; Xu et al., 2008). Therefore, a thorough understanding of mineral reaction mechanisms and kinetics in porous media is essential to improve the predictive capability of reactive transport models.…”

“…With increasing use, the combination of microstructural imaging (e.g., X‐ray micro‐CT scanning, 3D Raman imaging, positron emission tomography), pore network and pore‐scale modeling provide valuable insights for the derivation of extended REV‐scale constitutive equations (Agrawal et al., 2021; Kulenkampff et al., 2018; Menke et al., 2021; Noiriel & Soulaine, 2021; Poonoosamy et al., 2022; Roman et al., 2020; Soulaine et al., 2016). However, these extended laws have not been considered in recent modeling approaches, assessing the evolution of barrier interfaces of nuclear waste repositories (Xie et al., 2022) or geothermal systems (Tranter et al., 2021). One possible reason for this might be related to the unknown physical meaning of the added parameters and the difficulties in reliably defining them.…”

Editorial for Special Issue “Formation of Sulfate Minerals in Natural and Industrial Environments”

“…This includes desalination units, oil production, and hydrothermal systems. This is discussed by Tranter et al [15], who assessed the scaling potential of barite (BaSO 4 ) in fractured-porous reservoir rocks located in the Upper Rhine Graben, using a numerical model. They observed in silico that fractures significantly reduced the negative impact of the scale formation.…”