Aquifer CharacterizationUsing Advanced Borehole Geophysics

SCHLUMBERGER

On September 5, 1927, Conrad and MarcelSchlumberger ran the very first downhole electriclog in Pechelbronn, France. This event marked thebirth of both the Wireline industry andSchlumberger. Today, Schlumberger is the world’sleading supplier of technology and services forpetroleum reservoir characterization, productionand management and employs over 64,000highly-skilled people worldwide.

SCHLUMBERGER WATER SERVICES

Schlumberger Water Services (SWS) takespowerful approaches to minimizing uncertaintyand maximizing results for:

� Water Resource Management� Aquifer Storage and Recovery� Coastal Zone Groundwater Management� Water Solutions for Mines� Environmental Site Solutions� Groundwater Monitoring

Our team of engineers, hydrogeologists andgeophysicists integrate cutting-edge fieldtechnologies with data management andmodeling tools to solve complex groundwaterproblems. SWS provides our clients with thedecision-making framework for addressing shortand long-term water demands.

TECHNOLOGIES AND SERVICES

Schlumberger invests hundreds of millions ofdollars annually on product and servicesdevelopment, allowing us to provide some of themost sophisticated technologies, softwaresolutions, and services for complete subsurfacecharacterization. Our dedication to offering onlythe highest quality services and technologies,along with our approach to providing solutions-focused logging services as opposed to simplyqualitative, geophysical-data-focused services,sets our logging services apart from those offeredby your typical water well logging companies.

SCHLUMBERGER SIGNATURE TOOLS

� MAGNETIC RESONANCE TOOLS measure the magnetic resonance response of the free hydrogen in a formation’s pore space and is used to evaluate pore size distribution, effective porosity, total porosity, and hydraulic conductivity.

� HIGH-RESOLUTION IMAGING TOOLS create fully-oriented images in 3-D space of the electrical resistivity or acoustic properties of the formation around the borehole and are used to determine strikesand dips of bedding and fractures, and to evaluate rock/sediment texture.

� GEOCHEMICAL LOGGING TOOLS measure electronically-generated, neutron-induced spectral gamma ray activity, which is used to determine elemental weight fractions ofa number of key rock-forming elements.

� DIPOLE SHEAR ARRAY SONIC TOOLS use high-quality, monopole and dipole sources and measure compressional, shearand Stoneley slowness, which are used to determine stress anisotropies, geomechanical properties, porosity, permeability, and fracture permeability, along with calibrate surface seismic data.

� MODULAR DYNAMIC TESTER TOOLS measure aquifer pressures, collect fluid samples, provide permeability and anisotropy data, and conduct mini hydrofrac tests.

� ARRAY RESISTIVITY TOOLS measure formation electrical resistivity at five, highly-focused depths of investigation to delineate bedding as thin as one foot, evaluate drilling fluid invasion into the formation, and estimate formation water salinity.

Borehole Geophysical Technologies

HIGH-RESOLUTION BOREHOLE GEOPHYSICS

High-quality data and highly-skilled technicalanalysis are critical components of a successfulgroundwater management strategy. Our industry-leading geophysical logging services provide thefoundation for detailed aquifer characterization andvaluable conceptual model development, therebyreducing uncertainty and maximizing results forwater resource and water quality projects.

HYDROGEOLOGIC PROPERTIES

Schlumberger's innovative borehole geophysicaltechnologies are used to constrain the hydraulicproperties that control groundwater flow andcontaminant transport. Information from thesetechnologies are also used to optimally selectproduction, testing and injection aquiferintervals.

� Saturated and unsaturated hydraulic conductivity

� Transmissivity and storativity� Relative vertical flow profile� Capillary pressure� Pore pressure

FORMATION PROPERTIES

Schlumberger's high-resolution boreholegeophysical technologies measure continuousphysical properties that can be used to delineatelithology, and define stratigraphic correlations,which can be used to incorporate detailedheterogeneity in conceptual modeling.

� Pore size distribution� Effective and total porosity� Bulk density� Mineralogy� Bed thickness� Rock mechanical properties

GEOCHEMISTRY

Geochemical logging tools provide depth-continuous percentages of rock formingelements such as Si, Ca, Fe, S, Hg, Ni, Co, Cu,Mn, Cr, Gd, Cl, S, H, C/0 ratio, Ti, and Al.

In addition, depth-continuous estimates of in-situ and produced groundwater salinity aredetermined. Geochemical concentrationsmeasured from these tools are used to evaluategroundwater quality for production, recharge,and environmental projects.

� Elemental concentrations� Mineralogy� Lithology� Groundwater salinity� NAPL saturation� Potential arsenic bearing units� Discrete depth pore fluid samples

GEOMECHANICAL PROPERTIES

In-situ stress can be estimated frommeasurements of borehole breakout, induceddrilling fractures and minifrac testing.Geomechanical properties can also becalculated using acoustic and density wirelinetechniques. These data are used for assessingand predicting regional and local stressespertinent to the design of undergroundengineered structures and predictingsubsidence/deformation due to groundwaterpumping/injection.

� In-situ stress field and anisotropy� Rock strength, compressibility and rigidity

FRACTURES AND FAULTING

Fractures and faults may serve as conduits forgroundwater flow and contaminant migration.Information about the orientations andpermeability of these features support local andregional geomechanical assessments, thedesign of hydrologic tests and groundwatermonitoring networks. Borehole data along withcross-well and surface seismic surveys candetermine the continuity of fractures.

� Fracture identification� Fracture orientation, dip and aperture� Permeable fracture delineation� Fracture plane projection

Characterize Contaminated Site Complexity

Improve Aquifer ModelingSWS’ industry-leading logging technologies reduce risk and uncertainty when quantifyingaquifer properties, defining aquifer heterogeneity, and determining water quality in bothopen boreholes and cased wells. This valuable information will help to improve conceptualaquifer model development leading to realistic flow modeling.

� Evaluate the transmissivity, storativity and specific yield of the individual aquifer unit� Quantify depth-continuous hydraulic conductivity, total porosity, effective porosity,

and TDS in open and cased holes for model input� Differentiate aquifers and aquitards when modeling flow and transport � Define saturated and unsaturated zone properties� Quantify bed thicknesses, cross bedding characteristics, textural features,

heterogeneity, and bed contact dips and orientations� Characterize permeable fracture networks

Optimize Well DesignSchlumberger's borehole geophysical technologies offer a proven means for measuringdepth-continuous properties of an aquifer system and aiding in the design and constructionof groundwater supply, waste water injection, environmental remediation, and multilevelmonitoring wells. SWS’ range of advanced geophysical tools go beyond traditionalsubsurface characterization methods, and offers the ability for identifying aquifer propertiesinfluencing the yield, quality, and life expectancy of a water supply well.

� Identify high yield zones for optimal well design and improved well performance� Define grain size distribution to determine optimal screen type and design� Locate potential metal-bearing zones and potential arsenic-bearing zones for risk

mitigation� Define aquifer thicknesses and stratification � Quantify depth-continuous hydraulic conductivity, grain size distribution, total

porosity, effective porosity, mineralogy/lithology, and TDS

SWS provides specialized techniques for in-situ assessment of contaminated subsurface mediausing a combination of wireline logging, surface geophysical, and hydrologic testing techniques.Our full-service logging technologies quantify the amounts of contamination within the systemand provide depth-continuous, high-resolution data that is necessary for effective contaminanttransport modeling and treatment facility design.

� Quantify depth-continuous hydraulic conductivity, total porosity, effective porosity, & TDS� Measure concentrations of gamma-ray emitting radioisotopes and NAPL’s� Evaluate the transmissivity, storativity and specific yield of individual aquifers for

modeling� Define saturated and unsaturated zone soil properties to determine optimal groundwater

or soil remediation techniques� Determine fine-scale hydrogeologic features affecting flow and contaminant migration � Identify fractures, bed orientations and dips, which can influence contaminant migration � Obtain discrete depth, in-situ purged pore fluid samples and core samples

Borehole Geophysical Services

Constrain Surface Geophysics ProcessingSchlumberger is a pioneer in the development of surface electrical, electromagnetic andseismic technology, and in the usage of surface geophysical data to improve subsurfacecharacterization. SWS utilizes industry-leading borehole geophysical data in order toconstrain the inversion of surface geophysical data and to make advanced interpretations ofhydrogeologic properties across an aquifer system.

� Constrain the processing of surface geophysical data such as electrical, electromagnetic, seismic, and magnetic resonance inversions and interpretations using corresponding borehole technologies

� Interpret TDS, transport properties, and hydrostratigraphic variation along surface geophysical profiles, improving the aquifer model

� Forward model synthetic surface geophysical profiles from borehole geophysics used for survey design and as a base case for inversions

� Constrain surface geophysical depth interpretations, improving the processing of surface geophysical data

Characterize Fractured MediaSchlumberger offers high-resolution wireline logging tools that are used to detect andcharacterize fractures and faults within the formation. These features are visible where theyintersect the borehole and, in certain cases, beyond the borehole. Several ranges of verticaland horizontal resolution are possible.

� Quantify fracture orientations, dips and apertures allowing for the analysis of fracture density and porosity

� Identify permeable fractures� Project permeable fracture planes across site

Analyze Properties Behind Casing

Evaluate the formation properties in cased wells and identify zones where poor-water qualityis entering your well so that appropriate steps can be taken to eliminate the problem. SWSwill accurately evaluate the integrity of your production well and determine the cause ofproblems to reduce risk and assist with well rehabilitation.

� Determine formation total porosity, lithology, mineralogy, and TDS in order to accurately identify aquifer/aquitard conditions

� Identify which aquifers are producing poor quality water� Evaluate flow between casing and formation in order to diagnose a compromise in

the well integrity� Delineate voids and channels behind casing, determine annular fill placement� Inspect casing and screens for corrosion, and internal/external damage using imaging

and casing thickness logs

DATA INTERPRETATION AND INTEGRATION

SWS offers a complete range of services forprocessing, analyzing, and interpreting yourgeophysical data and for integrating theinterpretations into the hydrogeologicconceptual model. Our advanced softwareapplications allow us to develop and evaluaterealistic solution scenarios, minimizinguncertainty and maximizing results forgroundwater resource and quality projects.

Our data consulting services utilize:

� specialized tools that support advanced log interpretations and geological modeling

� artificial neural networks to automate the identification of discrete geologic facies from geophysical log curves

� extensive data analysis tools to assist in the identification of important statistical parameters and spatial trends in the data

� sophisticated algorithms to facilitate quantitative three dimensional modeling of depositional processes such as shoreline transitions and fluvial systems

DATA-DRIVEN AQUIFER MODELING

Effective utilization of geophysical data fordetailed geologic and hydrogeologic conceptualmodeling requires specialized yet flexibleintegration tools. As a key component of SWS’services, the Petrel* modeling system provides aseamless workflow from data importation todetailed three dimensional conceptual modeldevelopment for realistic groundwater flow andcontaminant transport simulation. Our tools forinterpretation and quantitative integration ofborehole geophysical logs, borehole imagery,and surface geophysical data help to assure thatyou achieve optimal value from your geophysicaldata and resulting hydrogeologic interpretations.

The Petrel modeling system provides:

� 3D models of key subsurface properties using geophysical well logs

� the option of using 3D facies models, 3D geophysical seismic attributes, and/or geostatistical models to control and condition the modeling

� the ability to combine modeling techniquesfor each run

� the ability to create discrete fracture networks

GROUNDWATER SIMULATION

SWS expands the geologic model into thesimulation environment where aquifer flow andcontaminant migration can be better understood.Building from the high-resolution geologic modeldeveloped in Petrel, our hydrogeologists useECLIPSE* for simulating flow and mass transport inhighly complex, variably saturated conditions, withthe ability to incorporate density effects whenmodeling brine or coastal aquifers, explicitly modelNAPLs and chemical reactions, and couplegeomechanical modeling with fluid flow.

ECLIPSE allows users to:

� mitigate modeling risk by using new workflows to resolve previous contradictions

� perform reliable fluid flow predictions� receive accurate risk assessments by

analyzing uncertainty in reserves and production estimates

In addition to Petrel and ECLIPSE, SWS offersthe Waterloo Hydrogeologic Software Suite(WHS), a range of applications engineered forgroundwater data management, analysis,modeling, visualization, and reporting. WithWHS, groundwater professionals have the toolsnecessary to manage all aspects of theirgroundwater and environmental projects.

Integrate, analyze, and visualize your geophysical data

Data Consulting Services

Building a strong foundation for aquifer characterization

www.water.slb.comJune 2006 SWS-03-07-22 ©Schlumberger *Mark of Schlumberger