This course provides an emphasis and illustrations of the importance of the interaction between seismology, geology, petrophysics and reservoir engineering. The main emphasis during the course is on practical application rather than extensive discussion around the theoretical background. All topics covered will be accompanied by a relevant exercise.
The course is designed for:
The role of petrophysics in exploration and production
Review of petrophysical principles
Review of main logging tools
The morning session is intended as a refresher of the basic analysis principles and tool responses. Two simple exercises (multiple choice) and visual interpretation of a synthetic well log, are used to establish the level of petrophysical knowledge of the participants.
Quick look evaluation methods and saturation determination
In the afternoon participants will practice quick look methods to make an initial visual interpretation of a Northern North Sea well followed by the preliminary interpretation of the well using a pre-programmed Excel spreadsheet.
Quick look evaluation methods and saturation determination (continued)
Basic and special core analysis methods
Wireline formation testing Clastic reservoir geology and clay types
The evaluation of the North Sea well will continue. Thereafter, the core analysis lecture will deal with various analysis methods employed by core laboratories. The core data from the Northern North Sea well will be interpreted to determine the compaction correction factor and electrical parameters (m & n). The last lecture will cover wireline formation testing tools and pressure interpretation plus sampling methods. The pressure data from the North Sea well will be interpreted to finalise the fluid distribution in the well.
The morning session will then go on to deal with clay mineralogy, distribution, properties and influence on logging tools.
Shaly sand analysis for effective porosity systems using Archie, Simandoux and Indonesian equations
The basis of the effective porosity interpretation methods will be discussed and the Indonesian equation will be applied to the Northern North Sea well.
Shaly sand analysis for total porosity systems using Waxman Smits equation Cut-off criteria
In the morning the experimental background of the Waxman Smits equation will be discussed along with the derivation of the clay corrected electrical parameters (m* & n*). The core data from the Northern North Sea well will be re-evaluated to derive the Waxman Smits parameters and the well will be re-evaluated. The derivation of appropriate cut-off criteria will be discussed and the appropriate cut-offs for the Northern North Sea well will be determined. This will show that there is very little difference between the total hydrocarbon content derived using the effective or total porosity systems.
Dual Water model and Juhasz normalised Qv method
Hydrocarbon differentiation in shaly sands
Evaluation of laminated shaly sands
In the afternoon the application of the Waxman Smits equation in the absence of core data will be discussed along with the Juhasz normalised Qv method and the Dual Water model. The problems and methods that may be applied to help with hydrocarbon differentiation in shaly sands will be described. For an exercise, the participants will be provided with log data from a West African well and use the techniques discussed to determine the hydrocarbon distribution. Thereafter the well will be evaluated by applying the three total porosity methods. The challenges of laminated sands will be discussed and the Southern North Sea well will be illustrated as an example.
Saturation height functions
Capillary pressure and reservoir simulation
The application of capillary pressure in the reservoir during the reservoir charge process will be described and the difference in capillary pressure characteristics and rock types discussed. The conversion of laboratory data to reservoir conditions will be described along with measurement methods including wettability and contact angles. The generation of saturation height functions from capillary pressure curves as well as log data will be described and the data from the Northern North Sea well evaluated.
Permeability prediction (including NMR logging) and statistical considerations Uncertainty ranges
The various methods that may be applied to derive permeability from log and core data for use in reservoir models will be discussed. Techniques to convert atmospheric air permeability to in-situ brine permeability will be described and the Northern North Sea data set will be utilised for this purpose. The statistical implications of simple crossplot methods will be discussed and the appropriate regression methods applied.
The use of Monte Carlo methods to quantify uncertainty ranges will be described and applied in the Northern North Sea well.
Probabilistic methods for the analysis of complex formations (main emphasis on carbonates)
The application of probabilistic methods for the evaluation of complex formations will be discussed and examples presented. For an exercise a multi-lithology Dutch mainland well will be evaluated. The differences between the deterministic and probabilistic methods will be compared.
Cased hole saturation determination and production logging
Wellbore seismic applications
Petrophysical support for geothermal projects, tight gas reservoirs and shale oil/gas projects
The logging tools and techniques available for use in cased hole wells will be described along with the principles of production logging. A more extensive discussion will be provided for wellbore seismic applications dealing with the principles of VSP surveys, generation of synthetics, log editing methods and Gassmann substitution. A single well synthetic of the UK North Sea well will be generated.
The course closes with a discussion on the methods that may be applied to use petrophysical data in geothermal projects and to recognise potential tight gas reservoirs and shale oil/gas prospects. The derivation of mechanical properties from log data to be used in planning frac jobs will be described.