Integrated Fractured Reservoir Characterization and Connectivity Study in the Cantarell Field

Bustos, Arturo; Eduardo, Aguirre; Febres, Anurfo; Villavicencio, Antonio; Shen, Feng

doi:10.2118/132241-ms

Cited by 3 publications

References 16 publications

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Stabilized Water-Cut in Carbonate Naturally Fractured Reservoirs With Bottom Water With an Implication in Well Spacing Design for Recovery Optimization

Prasun

Wojtanowicz

2020

Journal of Energy Resources Technology

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Maximum stabilized water-cut (WC), also known as ultimate water-cut in a reservoir with bottom-water coning, provides important information to decide if reservoir development is economical. To date, theory and determination of stabilized water-cut consider only single-permeability systems so there is a need to extend this concept to naturally fractured reservoirs (NFRs) in carbonate rocks—known for severe bottom-water invasion. This work provides insight of the water coning mechanism in NFR and proposes an analytical method for computing stabilized water-cut and relating to well-spacing design. Simulated experiments on a variety of bottom-water hydrophobic NFRs have been designed, conducted, and analyzed using the dual-porosity/dual-permeability (DPDP) commercial software. They show a pattern of water-cut development in NFR comprising the early water breakthrough and very rapid increase followed by water-cut stabilization stage, and the final stage with progressive water-cut. The initial steply increase of water-cut corresponds to water invading the fractures. The stabilized WC production stage occurs when oil is displaced at a constant rate from matrix to the water-producing fractures. During this stage, water invades matrix at small values of capillary forces so they do not oppose water invasion. In contrast, during the final stage (with progressing water cut), the capillary forces grow significantly so they effectively oppose water invasion resulting in progressive water cut. A simple analytical model explains the constant rate of oil displacement by considering the driving effect of gravity and viscous forces at a very small value of capillary pressure. The constant oil displacement effect is confirmed with a designed series of simulation experiments for a variety of bottom-water NFRs. Statistical analysis of the results correlates the duration of the stabilized WC stage with production rate and well-spacing and provides the basis for optimizing the recovery. Results show that stabilized water-cut stage does not significantly contribute to recovery, so the stage needs to be avoided. Proposed is a new method for finding the optimum well spacing that eliminates the stabilized WC stage while maximizing recovery. The method is demonstrated for the base-case NFR.

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Stabilized Water-Cut in Carbonate Naturally Fractured Reservoirs With Bottom Water With an Implication in Well Spacing Design for Recovery Optimization

Prasun

Wojtanowicz

2020

Journal of Energy Resources Technology

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Modeling Finite-Fracture Networks in a Partially Fractured Reservoir in the Middle East

Özkaya

2017

SPE Reservoir Evaluation &Amp; Engineering

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Summary Dual-porosity/dual-permeability simulation formulae are derived from reservoirs with an infinite network of fully interconnected conductive fractures. One aspect of fractured reservoirs is that not all have fully interconnected fracture networks. Most of the fractured reservoirs are only partially fractured. Partially fractured reservoirs, in contrast, consist of discrete bundles of conductive fractures and/or isolated fractures. The discrete-fracture bundles are interconnected within but are isolated from other bundles nearby. In case of partially fractured reservoirs, location, size, and shape of discrete-fracture bundles must be determined to populate the fracture grid of the dual-porosity or dual-porosity/dual-permeability simulation model. The purpose of this paper is to demonstrate how the location, size, and shape of interconnected-conductive-fracture bundles can be determined by integrating borehole-image data with depletion-curve analysis. The method was devised to populate a fracture grid of a preliminary dual-porosity simulation model for a small field in the Middle East. The field produces from a partially fractured carbonate reservoir and has only a few vertical wells. Fractures in the field are dispersed or layer-bound and seem to be related to folding. Depletion-curve analysis and image logs yield location, size, and shape of discrete-fracture bundles. Fracture porosity, permeability, and size of matrix block bounded by fractures within each fracture bundle can be calculated by use of fracture data from borehole-image logs. A critical justification for integrating image logs with depletion-curve analysis is that it is not possible to predict finite-fracture-network (FFN) location, size, and spacing only from analytical connectivity measures or stochastic discrete-fracture-network (DFN) models.

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Characterization of Fault Damage Zones and Associated Fracture Networks and Their Influence on Fluid Flow in the Tight Carbonate Reservoir

Shen¹,

Torres

Mosqueda

et al. 2017

Day 1 Mon, November 13, 2017

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In the tight carbonate reservoir located in onshore Mexico, fault damage zones and associated fracture networks represent major permeability structure and greatly affect fluid flow. In this study, we present a method for characterizing and modeling fault damage zones and fracture networks. The main objectives are to use fault damage zone and fracture network models to predict fluid-flow pathways in the reservoir and to understand their impact on well production performance. Appropriate geometric attributes are used for unsupervised seismic facies classification with the aim of delineating fault damage zones. The utility of the facies approach lies in its capacity for classifying the fault system with distinct classes based on the degree of fracturing. The three-dimensional fault damage zones are extracted and modeled from the seismic facies volume. A natural fracture network model in the target formation is deterministically built by meshing fracture lineaments that are automatically tracked along depth slices of the edge-enhanced curvature attribute. The fracture network model provides fracture characters in terms of fracture orientation, length, density and connectivity. Local fracture network models at individual wells can be built using fracture connectivity analysis technique. The fault damage zone model delineates fault zone architecture and spatial variability. Our results show that the main fracture sets parallel or subparallel to the fault zone strikes regionally. Fractures distribute surrounding fault damage zones with enhanced fracture density. A good correlation between the fault damage zones and the lost circulation is observed. Based on the production data, fault damage zones can act as fluid conduits. In some instances, fault damage zones can create flow barriers. Conditioned with well data, the conductivity of the fault damage zones and related local fracture networks is calibrated. Using the local fracture network model, the fluid flow pathways and fracture vertical connectivity are determined. With borehole breakouts and drilling induced fractures, the identified maximum horizontal stress orientation is in the NNE direction. Our results show that the conductive properties of fault damage zones and fractures could be affected by the stress state and in situ stress orientations. This explains the fact that the wells located in the fault damage zones and fractures with the orientations preferable for extension tendency or slip tendency have high productivity. The continuous fault damage zone model and the discrete fracture network model can be used to capture 3-D complexity of fluid flow in fault damage zones, improve the prediction of flow pathways and help the lateral or horizontal well design.

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Integrated Fractured Reservoir Characterization and Connectivity Study in the Cantarell Field

Cited by 3 publications

References 16 publications

Stabilized Water-Cut in Carbonate Naturally Fractured Reservoirs With Bottom Water With an Implication in Well Spacing Design for Recovery Optimization

Stabilized Water-Cut in Carbonate Naturally Fractured Reservoirs With Bottom Water With an Implication in Well Spacing Design for Recovery Optimization

Modeling Finite-Fracture Networks in a Partially Fractured Reservoir in the Middle East

Characterization of Fault Damage Zones and Associated Fracture Networks and Their Influence on Fluid Flow in the Tight Carbonate Reservoir

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