opErAtioN pEtropHySiCS

This is no secret that formation evaluation is commercially crucial for an operator and therefore is at the heart of GPCI´s approach. But maximizing the efficiency / timing ratio for logging jobs can have its pitfalls. In particular, there is often only one chance to obtain critical data. These constraints explain why GPCI, in recommending logging programs, always ensures that logging requirements and log quality are aligned with formation evaluation requirements. And optimized to acquire only what is needed, No more –  No less. In this context, GPCI offers the following services:

  • Logging program support and service contract optimization
    GPCI’s experts are deeply familiar with major services company’s tools and deliver logging program proposals and peer reviews, tendering services/reviews as well as tool string configurations, logging speed, multiple run sequences, etc. Optimization of service contracts bear a significant cost savings potential.
  • Field operations support
    GPCI offers real-time operational support – with 24/7 availability – to support and advise wellsite teams before, during and after logging operations and petrophysical data acquisition. This is provided remotely or on-site, depending on clients requirements. In addition, our on–duty petrophysics team can deliver real-time quick-look evaluations.
  • Data quality control (Wireline and LWD) as soon as received, data are Cross-checked and quality verified by our team.
    GPCI informs and advises customers in real time, on the quality of the acquired data and suggests improvements if required.
  • Operations reports
    GPCI delivers detailed operational reports, enclosing all relevant information to ensure a complete audit trail.
  • Database storage and management
    GPCI provides a private secured online server exclusively dedicated to your needs, remotely accessible and searchable.
    Data review, data sorting, files classification, update operations status, drilling operation follow up are all performed in house.

Reservoir Petrophysics

Petrophysics is the core of GPCI expertise. From log interpretation to pore scale modelling and SCAL experiments we offer a complete suite of services.

GPCI is a dependable partner in managing petrophysical projects, especially when it comes to processing and interpreting of borehole imagery, nuclear magnetic resonance and sonic scanner data, all competitively performed by our in-house experts.

Similarly, performing pore scale simulations to refine plays – beyond the constraints of lab dynamic fluid flow analysis – form a central part of GPCI‘s activities.

Beyond that, GPCI’s teams can also move on-site to represent its client and to ensure adequate data acquisition and data QC at source. Reservoir assessment studies based on (wireline) well log data embrace :

Matricial reservoir assessment

  • Carbonate and clastic approach
  • Core data integration
  • Pressure and dynamic data integration

Advanced petrophysics

  • Tight reservoirs
  • Low Resistivity / Low Contrast Pay plays
  • Thin bed analysis
  • Organic matter, kerogen assessment

Fractured reservoirs

  • Fracture characterization from conventional logs
  • Fracture density, aperture and porosity from image logs

Well log data handling
GPCI takes care of editing all well informations, turning any raw data into consistent and clean datasets (splicing, depth shifting, denoising etc.)

GPCI delivers detailed expertise reports, including acquired data discussion, methodologies applied, petrophysical interpretation, petroleum reservoir evaluation results, conclusions and recommendations.


GPCI provides also formation and cement integrity evaluations in cased hole environments

Formation evaluation

  • Cased hole logging job
  • Natural gamma ray logs
  • Pulsed neutron capture logs
  • Formation resistivity logs
  • Sonic and acoustic logs

Cement Placement Evaluation

  • Casing to cement bond (CBL)
  • Cement to formation bond (VDL)
  • Vertical extent
  • Annular distribution (USIT / IBC)

Petrophysics modelling and electrofacies generation

Electrofacies analysis and log prediction through wireline and core data integration:

  • Facies model construction including standard wireline logs or array data from single or multiple wells
  • Clustering techniques and neural network
  • Multi-Resolution Graph-Based Clustering
  • Dynamic Clustering
  • Self Organizing Map
  • Artificial Neural Network

Cluster analysis looks for similarities/dissimilarities amongst data points in multivariate space of logs and core data, in order to group them into classes, electrofacies :

  • Facies model propagation
  • Propagation of the final model to multiple wells in the project/
  • Log response prediction

borEHoLE iMAgEry : proCESSiNg AND iNtErprEtAtioN

Microresistivity and sonic borehole images (BHI) provide abundant data for geologists, petrophysicists, reservoir engineers, drilling engineers and geophysicists. They enlighten the sedimentological and structural settings of the drilled area, and can therefore greatly facilitate the understanding of conventional log responses (e.g., related to a low vertical resolution). In return, those data analysis greatly improve petrophysical interpretations, help to perform stress modelling, and are essential for well stability modelling and well planning. Raw and processed image data quality control and analysis are realized as follow :

Image processing

  • WL tools:
    Schlumberger tools (FMS, FMI, OBMI, Dual OBMI, UBI)
    Halliburton tools (emi/Xrmi, omri, cast)
    Baker Atlas tools (STAR, Earth Imager, GeoXplorer, CBIL)
    Weatherford (Hmi, cmi, omi, umi)
  • lWD images
  • Dipmeter measurements

Image analysis and interpretation

  • Borehole shape analysis, breakout/stress analysis
  • Dip analysis, structural dip removal
  • Structural interpretation
  • Fracture analysis (fracture density, fracture aperture, fracture porosity)
  • Image analysis (image porosity, quantification of vuggy porosity, textural analysis, image facies)
  • Thin bed analysis (NTG)
  • Integration of Image-Core-Log data
  • Multi well correlations and analysis


NMR is a powerful tool to help reservoir characterization. In some situations it even turns to be the key tool in the analysis. It is the only wireline log that can differenciate between free fluid and bound fluid. It is also a powerful tool to better interpret low resistivity / low contrast pay, or to perform direct fluid saturation computation in flushed zone – independently of resistivity measurements.

Raw and processed data QC

Processing of raw data

  • Porosity calibration
  • Phase angle correction
  • Stacking
  • Despiking
  • Inversion

T2 analysis

  • Porosity and permeability computation
  • Bound fluid / free fluid computation

2D NMR fluid typing

Log – Core Integration

  • Porosity and permeability calibration
  • T2 cutoff calibration
  • Fluid types calibration

Pore size and facies identification

Completion Optimization

Total Organic Carbon volume estimation from mineralogy corrected density and NMR porosity

CorE pEtropHySiCS : SCAL, kr AND CApiLLAry prESSurES; porouS NEtWork CHArACtErizAtioN

In addition to standard routine core analysis measurements, GPCI provides professional advice for Special Core Analysis (SCAL) for both carbonate and clastic reservoirs :

  • Design specific and personalized SCAL program, select SCAL tests to fully fit measurements purposes
  • Labs support and recommendation to acquire reliable, robust and useful data
  • Project management to improve cost efficiency, data quality and contracting support

Interpretation and application to Petrophysics :

  • SCAL report review and validation :
    Coring fluid, core preservations, core manipulations & results reliability
  • Capillary pressure modelling :
    Analytical formulation to relate water saturation and height above FWL (from primary drainage and forced imbibition).  Evaluation of wetting characteristics
  • Resistivity log interpretation (electrical properties):
    Archie parameters determination “m” and “n” and integration to
    reservoirs analysis
  • Relative permeability :
    Integrate and provide a better understanding of Multi-phased fluid flow through the reservoir. Essential for production petrophysics and to shift from static to dynamic modelling.
  • NMR core analysis :
    A core-to-log NMR calibration. Extraction of total & effective porosity, free fluids, mobile HC, oil viscosity, etc.
    Interpretation of pore size distribution and integration into a full pore network characterization.
  • Pore volume compressibility & elastic properties :
    Confining stress effect on porous media and permeability.


Geomechanical studies are important during many stages of hydrocarbon prospection, development and production: from well planning to well completion and production monitoring. It allows effective cost planning, optimizing oil and gas production rate and recovery, helps to decrease environmental risks and to avoid hazards.

Our practical expertise covers :

Evaluation of rock dynamic mechanical properties

  • Poisson’s ratio
  • Young’s modulus
  • Bulk modulus
  • Compressive strength
  • Tensile strength
  • Shear strength
  • Fracture toughness

In-situ Tectonic Stress Orientation Analysis

  • Recommendation of appropriate techniques to determine in-situ stresses
  • Borehole breakout analysis
  • Drilling-induced fractures analysis

Qualitative pore pressure prediction
Based on pressure and log information from surrounding wells and guided by the interval velocity trends from seismic data after refined velocity analysis, a prediction of potential pore pressure intervals is provided.
GPCI focuses on incorporation of all information available in all spatial directions around the borehole, including the analysis of potential production data which may have led to potential depletion of reservoirs.

Wellbore Stability Studies

  • Drilling efficiency optimization
  • Wellbore orientation / design optimization
  • Mud weight optimization
  • Casing shoe decisions

Sand Production Prediction and Sand Control

Reservoir compaction, compressibility and subsidence studies

Reservoir stimulation

Gas Storage

  • Cap rock integrity analysis
  • Pressure limits analysis