#Wells&Drilling
Description
Giovanni Da Pratt
Giovanni Da Pratt is a Ph.D. in Petroleum Engineering (1981) and MS in Geophysics (1977) from Stanford University, specialized in well test pressure transient tests analysis and reservoir evaluations; worked in technical and management positions in PDVA, Schlumberger, and Halliburton, and as consultant currently president of Daprat Well Testing, lectures on pressure transient analysis with Kappa engineering software, associated with MineaOil Limited and is the country manager for Leopardus Petroleum in Buenos Aires Argentina.
Has been main advisor testing exploration and appraisal wells in Venezuela, Colombia, Argentina, USA and Australia, in Plataforma Deltana, Camisea, Dragon and Patao, San Jorge and Neuquén, Perla gas carbonate, Santos basin, Alaska North slope, and the Orinoco heavy oil belt.
Has trained over a thousand engineers worldwide, as instructor for NExT, Schlumberger and for the IFP, in Buenos Aires, Argentina, Cape Town and Kuwait, for clients as Kuwait Petroleum Corporation, National Iranian Oil Company, PDVSA, Repsol, YPF, Halliburton, Schlumberger, Chevron. Tecpetrol, Pluspetrol, Wintershall and SPEI.
Was a SPE Distinguished Lecturer in 2003-2004 with the subject “Well Testing Management. Impact on Reservoir Evaluation and well productivity”. In 2016 was invited by the SPE Argentina to lecture on “Pressure Transient Analysis – a conventional look to non-conventional reservoirs”, has published over a hundred technical articles, presented at SPE conferences, author of the book “Well Test Analysis for Fractured Reservoir Evaluation”, Elsevier 1990,
Well testing has been in place for over 50 years. The benefits of using this technology have been published in numerous technical articles. A popular method for pressure data interpretation has been published back in year 1950 by Horner and still today can be applied.
Presently most of pressure transient analysis is carried out by commercial software which can handle quiet complex pressure data interpretation using analytical or numerical linear or non-linear solutions as well as considering permeability and porosity dependency on pressure for non-conventional reservoirs. However, and in spite of testing technology and software development advances, pressure data interpretation and test design are not an automated technique, it requires of professional human intervention to be successful.
Learn how to carry out a well test analysis and to know how the results are used to identify in quite a fast way compared to other methods the reservoir model associated to the drainage area of the well and how to determine the parameters related to the reservoir flow capacity as well as the evaluation of present well productivity which are results derived from Pressure Transient Analysis (PTA). The specific objectives follow:
- Provide a sound understanding of practical and advanced methods currently in use for pressure transient analysis.
- Understand why, when and how to test a well and in the right way.
- Understand the principles of fluid flow through porous media and nodal analysis.
- Learn how to interpret pressure transient data acquired in conventional and non-conventional oil or gas reservoirs
- Learn pressure data quality control and well test design exploration and development wells.
- Understand results derived from pressure transient analysis as added value defining in a short time the reservoir model associated to the well’s drainage area.
- Learn current models to interpret pressure transient tests, expected pressure and derivative response.
- Understand when to use a linear or nonlinear analytical or a numerical solution for pressure data interpretation
- Carry out practical exercises using a commercial specialized software that will be available throughout the duration of the course.
- Reservoir and petroleum engineers
- Production engineers
- Exploration and development geoscientists
- Well test engineers
- Professionals working in reservoir and production engineering that need to learn about well test analysis or to get an updated on well test modern interpretation methods.
This training can be done in house based on workshop sessions for groups of delegates with interest in Conventional and Special Core Analysis; it can be tailored to specific company needs.
Day 1
Introduction to Well Test and Well Test Interpretations
- Well test definition and applications
- Well testing objectives
- Well test types
- Reservoir and well information derived from pressure tests data analysis
- Learning methodology
- Pressure transient analysis methodology.
On day 1 a brief introduction is given to well testing, the well test analysis methodology also referred to as Pressure Transient Analysis, well-testing objectives as well as the type of tests.
Day 2
Diffusivity equation and basic solutions for pressure transient analysis
- Diffusivity equation, Darcy’s law pressure stationary conditions.
- Darcy’s Law Diffusivity Equation Infinite radial Flow solution, limited drainage area, and Pseudo steady state Constant Pressure
- Pressure derivative, reservoir models used for pressure data interpretation, pressure responses considering well conditions, reservoir type, drainage area discontinuities, and limits
- Examples of Reservoir and Well Models used for interpretation.
- Hydraulically Fractured Wells. Double Porosity. Radial composite. Partial Penetration
- Horizontal Wells and Non-conventional reservoirs.
On day 2, a few reservoir models and the expected pressure response will be presented with the expected pressure response considering well conditions, reservoir type, drainage area discontinuities, and limits.
Day 3
Wellbore storage effects and skin factor
- Introduction of wellbore storage effects and skin factor
- Wellbore storage effects recognizant log-log diagnostic plot, Skin effects
- Drawdown and Pressure Build up analysis, Superposition principle applications
- Average reservoir pressure determination and Interference tests
- Meaning of the sometimes-called false pressure P* in a build up period
- Integrating geology, seismic and petrophysical models
- Pulse testing, interference testing, and deconvolution method.
In the day 3 it will be covered the skin factors, the wellbore storage effects that will always be present no matter the type of test, wellbore storage effect recognized on the pressure response, initial pressure data trend shows a unit slope tendency in log-log diagnostic plot, no information from the reservoir can be obtained during the pure wellbore storage period, is like having the well disconnected from the reservoir.
Day 4
Diffusivity equation for gas reservoirs
- Not linear and the pseudo pressure potential
- Real gas potential pseudo pressure m(p function)
- Initial pressure acquired in the gas well is converted to m(p)
- Pseudo gas potential. Turbulence effect. Drainage radius and interpretation example
- Backpressure tests: Flow after flow, Isochronal, and Modified Isochronal
- Extended and short-term time test, DST, identifying faults in the drainage decline, inferring that a small reservoir size or drainage area is associated with the well
- Pressure behaviour for sealing outer boundary and constant pressure outer boundary
- Example inspired on field case
On day 4, it will be described the diffusivity equation for gas reservoirs, the pseudo pressure potential or real gas potential expressed as a linearized equation of pseudo pressure m(p), and pressure analysis methodology.
Day 5
Pressure test in injector wells, horizontal wells, and spherical flow
- Diffusivity equation in injector wells, water, and oil bank pressure responses
- Mobility ratio definition and fall off test interpretation, step rate injection test
- Interpretation models for hydraulically fractured wells, infinite conductivity, uniform flux, and finite conductivity
- Well tests in non-conventional reservoirs, dual-porosity models
- Well test in horizontal wells
By the end of day 5, the participants will have a good knowledge of pressure tests in injector wells, horizontal wells, double porosity reservoirs, and spherical flow. At the end of the training, they will have acquired a wide understanding of well-testing planning, design, execution, and interpretation.
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