Integrate all available data into a single full-field reservoir model that helps reduce costs and improve oil recovery

Today, with operators working in more complex areas, geo-mechanics requirements are more demanding and meeting them is crucial to the success of field development planning. The removal of hydrocarbons from a reservoir or the injection of fluids or gas changes the rock stresses and geomechanics environment, potentially inducing compaction and subsidence, affecting well and completion integrity, altering caprock and fault-seal integrity, changing fracture behavior and thermal recovery, and affecting CO2 disposal and gas storage. Proper geomechanical modeling can be used to help prevent these issues, which can be costly to remedy.

The Schlumberger Reservoir Geomechanics Center of Excel-lence (RGCoE) uses an innovative approach and pioneering technol-ogy in the development of unique earth modeling techniques to help reduce costs and improve oil recovery. The RGCoE uses an advanced coupled reservoir model-ing technique that relates stress to reservoir properties, making it possible to design, develop, and operate entire fields in ways that increase well longevity and mitigate effects that could detrimentally affect life-of-field operations and economics.

BEYOND THE WELLBORETraditional geomechanics services have focused on a single well to identify, predict, and prevent costly events and to optimally manage that well. More and more, opera-tors are considering the impact of geomechanics in the reservoir, beyond the single well model and up to field development planning and management.

Geomechanics and reservoir behavior are tightly coupled: Reservoir pressures and produc-tion/injection affect the stresses and displacements in the reservoir and surrounding rocks. This in turn alters the reservoir properties (po-rosity, permeability, etc.) that affect the performance of the reservoir

and individual wells. This complex response can be modeled using advanced numerical techniques, and some of the computational solutions—particularly within the reservoir and overburden—can be observed with monitoring techniques, for example 4D seismic and microseismic.

DRIVEN BY DATAA successful geomechanics model is based on knowing how to use all oilfield data efficiently and effectively. Data is taken from every available source at every stage in the reservoir development. Initially, all available data is gathered and combined in the construction of the mechanical earth model (MEM).

4D Reservoir Geomechanics

Casing points

Overpressure

3D, 4D, and microseismic

Fault stability Fractured reservoirs

Wellbore instability and/or stuck pipe

Lost circulation Subsidence

CompactionStimulation

Completion integrity

Geomechanics in the reservoir

Effects occur in the reservoir and the over- and under-burden, not only in weak compacting rocks. Geomechanics can affect depletion, hot/cold injection, disposal, CO2 , and underground storage.

4D Reservoir Geomechanics

Models are built from 3D structural models plus all available 1D models built from extrapolated and interpreted downhole measurements.

Far-field boundary conditions are then imposed and matched with stress and strain measurements and other observations. The computed effects of stress in wells can also be calibrated against observations such as fracturing and breakout from FMI* Fullbore Formation MicroImager data or data from the Sonic Scanner* acoustic scanning platform. Other inputs for geomechanics studies include seismic data, pressure, and temperature measurements as provided by Sensa* fiber-optic monitoring systems and GPS terrestrial surveys that locate changes in elevation.

A starting reservoir model is expanded to include overburden, sideburden, and underburden cells. The stress modeling follows an iterative process and modeling route—involving verification of all input data into a fully consistent model and verification of the engineering properties such as logs, breakouts, and faults to define the initial stress state. By incorporating new information in a feedback loop, these models evolve, reducing uncertainty in predictions and extracting maxi-mum value from the new data.

The resulting model can be used as a source of stress data for several key stages:

n well planning—wellbore stability and optimum drilling

n well completions—sand management

n formation stimulation—hydraulic fracture design

n field management—pressure maintenance and injection

n well integrity—well design to accommodate formation strain from, for instance, compaction and subsidence, as the well is produced.

Importing from ECLIPSEor Petrel software or both Importing fault surfaces

Embedding in overburden,underburden, and sideburden

Population with properties and assign behavioral models

Initialization and coupledsimulation (parallelization)

Data and results utilizedin engineering designs

and planning

VISAGEsimulation

ECLIPSEsimulation

Δp, ΔT

Δkij, ΔVpore

4D coupled reservoir geomechanics modeling.

Proprietary modeling and simulation software n VISAGE* stress simulatorn MMRD* interactive software

applications enabling seismic to simulator workflows

n Sand Management Advisor n Petrel* seismic-to-simulation

workflow n ECLIPSE* Geomechanics

reservoir simulation softwaren Microseismic applications

POWERED BY TEcHNOLOgYThe interaction between geology, fluid movement, and stress changes induced by drilling operations or other production scenarios is a complex 4D process. This interaction continually evolves over time, adding yet another dimension of complexity. Over the life of any productive field, innumerable events alter the initial geomechanical framework between the reservoir and the surface.

The Schlumberger Reservoir Geomechanics Center of Excellence (formerly V.I.P.S., a UK-based software and consulting company) pioneered the development of the world’s first coupled geomechanics stress-dependent reservoir simulator. The VISAGE geomechanical simulator solves complex stress equations and relates the rock stresses to reservoir properties. The technol-ogy is key to the development of 3D and 4D MEMs that predict the geomechanical behavior of the reservoir during production and injection.

The VISAGE software couples rock stresses to reservoir simulators such as the ECLIPSE reservoir simulation software to provide permeability and porosity updating in the fluid-flow calculations. The software is also used in 3D geologi-cal geomechanical inversion and for analyzing structural integrity of casing and well completions in deforming rock masses.

Schlumberger is developing links between VISAGE and ECLIPSE reservoir simulation software and other reservoir workflows such as the Petrel seismic-to-simulation technology. This will enable seamless mechanical earth modeling from seismic, logs, and laboratory tests to coupled geomechanics and reservoir analyses and engineering designs.

Majoreffectivestress σ1

Tensile strength Minor effective stress σ3

Uniaxial compressive strength

Stress and pressure act upon every reservoir, wellbore, and completion. Drilling, production, and injection processes modify these stresses and pressures, sometimes to the operator’s detriment. Advanced modeling can help prevent undesired results.

schlumberger tools for measurementsn sEIsMIc ● Q-Marine* single-sensor

marine seismic system ● Q-Borehole* integrated

borehole seismic system n LOgs ● Sonic Scanner* acoustic

scanning platform ● Platform Express* integrated

wireline logging tool ● PressureXpress* reservoir

pressure-while-logging service ● MDT* Modular Formation

Dynamics Tester ● FMI* Fullbore Formation

MicroImager ● UBI* Ultrasonic Borehole Imager n cOREs ● TerraTek lab testing and

core/log integration

VISAGE stress simulator model.

APPLIcATIONs FEATuREs ADVANTAgEs

Deep water Pore pressure prediction Reduced NPT Dynamic stress analysis Improved well planning Coupled reservoir modeling Risk mitigation Casing string reduction Well integrity Longevity of completion

unconventional gas Microseismic monitoring programs Optimized stimulation design Stress modeling Field development planning Ground substance movement monitoring

Heavy oil Coupled reservoir modeling Reservoir optimization Ground movement prediction Production optimization Risk mitigation

cO2 storage Coupled reservoir modeling Site selection assessment Fault and caprock integrity analysis Risk mitigation Field optimization

Brownfields Reservoir integration analysis Risk mitigation Compaction and substance modeling Performance optimization Coupled reservoir modeling

underground gas storage Coupled reservoir modeling Reduced cushion gas Fault and caprock integrity analysis Well design optimization Well integrity analysis Facility longevity optimization Risk mitigation

Fractured reservoirs Coupled reservoir modeling Optimized well planning and placement Permeability enhancement Avoidance of water production and breakthrough

compaction & subsidence Coupled reservoir modeling Risk mitigation Reservoir and overburden movement analysis Well integrity analysis

4D seismic Forward modeling in geophysics Optimized timing of 4D seismic survey response Improved 4D seismic interpretation

4D Reservoir Geomechanics

www.slb.com/geomechanics

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