Fundamental controls on fluid flow in carbonates: current workflows to emerging technologies

Agar, Susan M.; Geiger, Sebastian

doi:10.1144/sp406.18

Cited by 54 publications

(22 citation statements)

References 456 publications

(416 reference statements)

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“…Reactive transport modelling (RTM), which couples fluid flow and geochemical reactions along flow paths, is an emerging numerical tool which can be used to identify and quantify major controls on water-rock interaction, and can help to improve predictions of diagenetic modification of reservoir quality (Steefel et al, 2005;Agar and Geiger, 2015). Reactive transport phenomena involve the synergistic interplay of simultaneous chemical reactions and fluid transport in geologically heterogeneous rocks, which is not possible to understand with the help of transport-only or chemical speciation-only models.…”

Section: Introductionmentioning

confidence: 99%

Reactive transport modelling of hydrothermal dolomitisation using the CSMP++GEM coupled code: Effects of temperature and geological heterogeneity

et al. 2017

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University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Reactive transport modelling of hydrothermal dolomitisation using the CSMP++GEM coupled code:Effects of temperature and geological heterogeneity AbstractReactive transport simulations using our CSMP++GEM coupled code were applied to study the major controls on replacement dolomitisation and the development of dolomite geobodies in a hydrothermal setting. A series of 2D simulations show how elevated temperature and reactive surface area increase the rate of dolomitisation, and result in a dolomite replacement front that is both sharper and inclined at a higher angle from vertical. This inclination, an effect of gravity segregation, is apparent in thick homogeneous units, but in layered systems the lithological contrast determines the shape of the dolomite front. The increase in permeability resulting from porosity generation upon replacement of calcite by dolomite has a major effect on accelerating the overall progress of dolomitisation. In contrast, the changes in fluid density due to chemical reactions and the pressure dependence of thermodynamic data have a minor influence under simulated conditions. Primary dolomite forms slowly after complete replacement of host calcite, leading to porosity decrease, and is only locally important around the source of the hydrothermal fluid.For a simple layered system, our model results are in excellent agreement * Corresponding author. Present address: ETH Zurich, Institute of Geochemistry and Petrology. E-mail address: alina.yapparova@gmail.comPreprint submitted to Chemical Geology July 6, 2017with those obtained using TOUGHREACT code. They do, however, show the advantage of unstructured triangular over structured rectangular meshes for resolving complex curved/inclined front shapes. Such meshes also offer benefits in simulating fault-controlled hydrothermal dolomitisation. Our simulations predict dolomite geobodies comparable in scale and morphology to natural examples documented at outcrops, and underline the importance of understanding the permeability structure within and around the fault zone.

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Section: Introductionmentioning

confidence: 99%

Reactive transport modelling of hydrothermal dolomitisation using the CSMP++GEM coupled code: Effects of temperature and geological heterogeneity

et al. 2017

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“…Fractures are widespread in nature and, depending on their density and their aperture, might have a strong impact on fluid flow and fluid aquifers (Berkowitz, 2002;Rzonca, 2008), in addition to potentially affecting geothermal (Montanari et al, 2017;Wang et al, 2016) and hydrocarbon reservoirs (Agar and Geiger, 2015;Lamarche et al, 2017;Solano et al, 2010) They are typically organised as networks rang-538 P.-O. Bruna et al: A new methodology to train fracture network simulation ing from the nanometre to the multi-kilometre scale (Zhang et al, 2016), and they present systematic geometrical characteristics (i.e.…”

Section: The Importance Of the Prediction Of Fracture Network Geometrymentioning

confidence: 99%

A new methodology to train fracture network simulation using multiple-point statistics

Bruna¹,

Straubhaar²,

Prabhakaran³

et al. 2019

Solid Earth

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Abstract. Natural fracture network characteristics can be establishes from high-resolution outcrop images acquired from drone and photogrammetry. Such images might also be good analogues of subsurface naturally fractured reservoirs and can be used to make predictions of the fracture geometry and efficiency at depth. However, even when supplementing fractured reservoir models with outcrop data, gaps will remain in the model and fracture network extrapolation methods are required. In this paper we used fracture networks interpreted from two outcrops from the Apodi area, Brazil, to present a revised and innovative method of fracture network geometry prediction using the multiple-point statistics (MPS) method. The MPS method presented in this article uses a series of small synthetic training images (TIs) representing the geological variability of fracture parameters observed locally in the field. The TIs contain the statistical characteristics of the network (i.e. orientation, spacing, length/height and topology) and allow for the representation of a complex arrangement of fracture networks. These images are flexible, as they can be simply sketched by the user. We proposed to simultaneously use a set of training images in specific elementary zones of the Apodi outcrops in order to best replicate the non-stationarity of the reference network. A sensitivity analysis was conducted to emphasise the influence of the conditioning data, the simulation parameters and the training images used. Fracture density computations were performed on selected realisations and compared to the reference outcrop fracture interpretation to qualitatively evaluate the accuracy of our simulations. The method proposed here is adaptable in terms of training images and probability maps to ensure that the geological complexity in the simulation process is accounted for. It can be used on any type of rock containing natural fractures in any kind of tectonic context. This workflow can also be applied to the subsurface to predict the fracture arrangement and fluid flow efficiency in water, geothermal or hydrocarbon fractured reservoirs.

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“…). A key to improving production from a faulted carbonate reservoirs is better understanding and prediction of the fluid flow (Agar & Geiger ).…”

Section: Introductionmentioning

confidence: 99%

“…It is estimated that up to 50% of the world's oil and gas reserves are located in carbonate reservoirs (Chilingarian et al 1992). A key to improving production from a faulted carbonate reservoirs is better understanding and prediction of the fluid flow (Agar & Geiger 2015).…”

Section: Introductionmentioning

confidence: 99%

Laboratory observations of fault transmissibility alteration in carbonate rock during direct shearing

et al. 2016

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We present the results of hydromechanical changes across and along the evolving rupture surface of carbonate rocks during direct shear experiments. Direct shear experiments were performed on a laminated travertine of continental, microbial origin with calcite content of 99 wt%, chosen as a lithological analogue for Aptian presalt oil reservoir rocks found in South Atlantic presalt basins. Medical X‐ray CT images show that the porosity (~9–13%) is mainly composed of subplanar pores and vugs. Permeability is high along the laminations (~50–200 mD), controlled by interconnected pores and fractures, and extremely low across the laminations (≪1 mD). Six intact samples of travertine were sheared across the bedding direction to short displacement (20 mm), and a further three samples were sheared to a much longer displacement (120 mm). A constant effective vertical stresses of either 35, 40 or 45 MPa was applied throughout the tests. Fluid flow response across and along the fault zone was monitored continuously during both shear deformation (dynamic transmissibility) and hold periods (static transmissibility), while keeping a constant pore pressure throughout the measurement. While the samples show some microstructural variability, the set of samples sheared to 20‐mm displacement followed the same early kinematics and show very similar mechanical response to that seen in the same period of the samples where shear was continued on to 120‐mm displacement. After 20‐mm displacement, the microstructures are dominated by fractures in a zone 10–20 mm wide resembling a typical fault damage zone, with only thin and patchy development of gouge on the principal displacement plane. In all of the samples sheared to a high displacement of 120 mm, a continuous layer of gouge (6.2–13 mm thick) was formed, defining a distinct core of the shear zone. The dynamic transmissibility across the fault decreases progressively in all the sheared samples regardless of the applied effective stress. In general, the volume decreases as well, though at a tapering rate, throughout shear. A small vertical dilation occurred near the peak strength for travertine sheared under 35 MPa vertical stress, but this was not accompanied by an increase in transmissibility. From the results, we conclude that once the gouge material is developed in the core of the fault zone, the dynamic transmissibility across the fault is permanently decreased.

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Fundamental controls on fluid flow in carbonates: current workflows to emerging technologies

Cited by 54 publications

References 456 publications

Reactive transport modelling of hydrothermal dolomitisation using the CSMP++GEM coupled code: Effects of temperature and geological heterogeneity

Reactive transport modelling of hydrothermal dolomitisation using the CSMP++GEM coupled code: Effects of temperature and geological heterogeneity

A new methodology to train fracture network simulation using multiple-point statistics

Laboratory observations of fault transmissibility alteration in carbonate rock during direct shearing

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