Physical Changes of Reservoir Properties Caused By Subsidence and Repressuring Operations

Allen, D.R.

doi:10.2118/1811-pa

Cited by 36 publications

(14 citation statements)

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“…For example, the Wilmington field, located in Long Beach (California), experienced a maximum subsidence of about 9 m as a result of oil production for over 20 years. Associated with surface subsidence, maximum horizontal displacements as large as 3.7 m were recorded [2]. Another well-known case is the Ekofisk field, in the Norwegian sector of the North Sea.…”

Section: Introductionmentioning

confidence: 99%

“…Simulation models include: (1) finite difference and finite volume procedures, limited to elastic response or explicit treatment of plasticity [27,32,34,35]; (2) finite element procedures for the mechanics without coupling with the flow field [16,25]; (3) finite elements for the mechanics problem and finite volumes for the flow problem, limited to poroelastic behavior [13,15]; and (4) fully coupled, finite element models for flow and mechanics [11,21,22,24,39,40]. All of these models are based on the displacement formulation of the linear momentum balance equation.…”

Section: Introductionmentioning

confidence: 99%

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A locally conservative finite element framework for the simulation of coupled flow and reservoir geomechanics

2007

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In this paper, we present a computational framework for the simulation of coupled flow and reservoir geomechanics. The physical model is restricted to Biot's theory of single-phase flow and linear poroelasticity, but is sufficiently general to be extended to multiphase flow problems and inelastic behavior. The distinctive technical aspects of our approach are: (1) the space discretization of the equations. The unknown variables are the pressure, the fluid velocity, and the rock displacements. We recognize that these variables are of very different nature, and need to be discretized differently. We propose a mixed finite element space discretization, which is stable, convergent, locally mass conservative, and employs a single computational grid. To ensure stability and robustness, we perform an implicit time integration of the fluid flow equations. (2) The strategies for the solution of the coupled system. We compare different solution strategies, including the fully coupled approach, the usual (conditionally stable) iteratively coupled approach, and a less common unconditionally stable sequential scheme. We show that the latter scheme corresponds to a modified block Jacobi method, which also enjoys improved convergence properties. This computational model has been implemented in an objectoriented reservoir simulator, whose modular design allows for further extensions and enhancements. We show several representative numerical simulations that illustrate the effectiveness of the approach.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A locally conservative finite element framework for the simulation of coupled flow and reservoir geomechanics

2007

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“…For example, the Wilmington field, located in California, experienced a maximal subsidence of about 9 m as a result of production over 20 years. Horizontal displacements as large as about 4 m were also recorded (Allen 1968). Another example is the Ekofisk field in the North Sea, where a sea-floor subsidence of 42 cm per year was reached in 1990 (Sylte et al 1999).…”

Section: Geomechanical Effects In Produced Reservoirsmentioning

confidence: 94%

Rock physics and geomechanics in the study of reservoirs and repositories

David

Ravalec-Dupin

2007

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Reservoir management for hydrocarbon extraction and repositories design for radioactive waste storage are two different areas in which rock physics and geomechanics provide valuable information. Although the targets and objectives are different, similar approaches and common attributes exist in both fields: safety assessment, short-to long-term prediction, integration of various scales of investigation, and remote monitoring, among others. Nevertheless, there are also important differences: reservoirs at depth are investigated through remote geophysical studies, well-logging and/or core samples retrieval, whereas direct access to repositories is possible through excavation in the host formation in which underground research laboratories can be constructed. We review a number of studies focusing on geomechanics and rock physics applied to the characterization of reservoirs and repositories, including laboratory experiments and predictive models, at different scales.Reservoir management and assessment of repository performance require the integration of different fields in Earth sciences, including geochemistry, geophysics, structural geology, and, in the case of interest here, rock physics and geomechanics. We present recent advances in the studies of reservoirs and repositories with the aim of emphasizing how rock physics and geomechanics help to obtain a better insight into important issues linked to reservoir management for exploitation of natural resources, and to repository safety assessment for hazardous waste storage in the geological environment.In the area of reservoir management, the importance of geomechanics in problems such as wellbore stability, hydraulic fracturing and subsidence is well known. Recently, there has been a growing interest in the development of a link between fluid flow simulators and geomechanical models. Several approaches have been proposed to incorporate the correct physics and to account for physical phenomena usually neglected in reservoir simulation. New techniques developed in laboratory studies provide relevant data for this integration. The approaches differ in the degree of coupling. The stronger the coupling, the more computationally demanding the simulation. Numerical experiments showed that coupling is of interest for poorly consolidated reservoirs such as chalk reservoirs. In other cases, one may wonder whether a more accurate modelling of production processes justifies the required computation cost. Complementary sensitivity studies have to be performed to better estimate the conditions in which the coupling is worthwhile.In the area of underground waste storage, the key issue is to design a repository as safe as possible for human activity and for the environment at the near surface, on time scales of the order of hundreds of years. This challenging task requires us to identify favourable geological targets for the storage, and to develop extensive scientific research in different fields, so as to obtain eventually a predictive model of the repository evolu...

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“…Production comes from seven zones of Pliocene-and Miocene-age high-porosity sands (33 to 37%) at 800 to 1900 m depth that have not experienced deeper burial in geological times. 13 Massive reservoir compaction and production-stress changes induced severe casing damage to more than 500 wells, including compression damage within the producing interval and shear damage within the producing intervals and in the overburden. Casing-collar logs show that 15-m casing joints were shortened as much as 400 mm within producing intervals.…”

Section: Wilmington Earthquakes: Production Shearingmentioning

confidence: 99%

Casing Shear: Causes, Cases, Cures

Dusseault¹,

Bruno

Barrera

2001

SPE Drilling &Amp; Completion

123

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Casing impairment leads to loss of pressure integrity, pinching of production tubing, or an inability to lower workover tools. Usually, impairment arises through shear owing to displacement of the rock strata along bedding planes or along more steeply inclined fault planes. These displacements are shear failures. They are triggered by stress concentrations generated by volume changes resulting from production or injection activity. Volume changes may arise from pressure changes, temperature changes, or solids movement (solids injection or production).Dominant casing-deformation mechanisms are localized horizontal shear at weak lithology interfaces within the overburden; localized horizontal shear at the top of production and injection intervals; and casing buckling within the producing interval, primarily located near perforations.Mitigating casing damage usually means reducing the amount of shear slip or finding a method of allowing slip or distortion to occur without immediately affecting the casing. Strengthening the casing-cement system seldom will eliminate shear, although in some circumstances it may retard it. Proper well location or inclination, underreaming, special completions approaches, reservoir management, and other methods exist to reduce the frequency or rate of casing shear. Shearing MechanismsCasing shear is caused by rock shear. Rock shear is caused by changes in stress and pressure, induced by typical petroleumrecovery activities such as depletion, injection, and heating.

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Physical Changes of Reservoir Properties Caused By Subsidence and Repressuring Operations

Cited by 36 publications

References 0 publications

A locally conservative finite element framework for the simulation of coupled flow and reservoir geomechanics

A locally conservative finite element framework for the simulation of coupled flow and reservoir geomechanics

Rock physics and geomechanics in the study of reservoirs and repositories

Casing Shear: Causes, Cases, Cures

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