Course contents
Hydrocarbon reservoirs: conditions for the existence of an oil
or gas reservoirs, sedimentology, generation of hydrocarbons and
their migrations, hydrocarbon traps, temperature and pressure in
the reservoir.
Reservoir fluids: composition, phase behavior of hydrocarbons
systems under reservoir conditions, thermodynamic properties of
reservoir fluids, volumetric behavior of gases and condensates,
volumetric behavior and viscosity of oil, viscosity of oil with
dissolved gas, correlations for estimating the solubility of gas
into oil, the formation volume factor, the compressibility of oil,
property of reservoir water.
Reservoir rocks: core logs, porosity, compressibility,
wettability, basic concepts of capillary, drenage and imbibition,
capillary pressure curves, conversion of laboratory capillary
pressure curves to reservoir conditions, calculation of the average
capillary pressure curve for a reservoir –Leverett J-Function,
porosity, absolute permeability. Dynamic properties of rocks:
porosity, permeability, relative permeability curves (gas-oil, and
oil- water), effective permeability, calculation of the average
relative permeability curve in a sedimentary unit, the use of
statistical analysis in reservoir zonation.
Evaluation of oil and gas reserves: definitions, classification
of reserves according to production status, basic data for the
volumetric calculations of reserves, reservoir area, net pay
thickness, porosity and average porosity, water saturation and
average water saturation, oil volume factor, gas volume factor,
recovery factor.
Classification of Fields in terms of hydrocarbon volume.Radial
flow through porous media for slightly compressible fluids:
equation of single flow radial flow, linearisation of the
diffusivity equation, horizontal radial flow, dimensionless form of
the radial diffusivity equation of fluid of constant
compressibility, solution of the diffusivity equation for
transient, pseudo steady-state and steady state flow, treatment of
real well, skin effect. The principle of superimposition applied to
the solution of the diffusivity equation.
Interpretation of production tests in gas and oil wells.
The influx of water into the reservoir by the following methods:
Schilthuis, Huntus , global equation, Van Everdingen and Hurst, and
Fetkovich .Material balance equation and prediction of the gas
production as function of time for : dry gas reservoirs in contact
with an aquifer and for condensate reservoirs. Pressure maintenance
by water injection or gas recycling in gas condensate reservoirs.
Calculation of the volumetric and phase behavior of a condensate
reservoir using EOS.
General material balance equation for oil reservoirs, drive
indices , material balance for undersaturated oil and saturated oil
reservoirs without gas cap. Immiscible displacement in homogeneous
porous media: the fractional flow equation, the Bukley-Leverett
displacement equation, fraction flow curves concave downward,
upward, and S-shaped.Calculation of the average saturation behind
the displacing front by Welge's equation. Calculation of oil
recovery as function of time. The effect of oil viscosity and flow
rate on displacement process.
Factor influencing oil recovery by water injection: microscopic
displacement efficiency, volumetric efficiency, vertical invasion
efficiency. Water and gas coning , calculation of the critical flow
rate for water and gas coning.
Simulation of reservoir behavior using numerical modeling:
philosophy and methodology behind numerical modeling,
classification of models based on geometry and classification and
number of mobile phases, the continuity equation, flow equation of
single phase flow of slightly compressible fluid, flow equation for
gas fluid, equation for a two and three phases models without mass
exchange among phases, black oil model for heavy oil reservoirs,
volatile oil model, compositional flow model.
Basic principle of Finite Difference (FD) method for the
numerical integration of the partial differential equations
regulating the behavior of the reservoir models: finite difference
analogs for the spatial derivatives of the first and second order,
truncation errors and stability condition for a FD scheme. Matrix
form of a FD scheme. Different grade of implicitness in the
simulation of multiphase models: IMPES (implicit Pressure Explicit
saturations), SEQ (Sequential method), SIMULTANEOUS (full implicit
method).
Readings/Bibliography
G. L. CHIERICI, Principi di Ingegneria dei giacimenti
petroliferi, volls. 1-2, AGIP, 1991.
G. L. CHIERICI. Principles of Petroleum Reservoir
Engineering, volls 1 and 2. Springer-Verlag, Berlin, New
York, 1995.
L. P. DAKE, Fundamental of reservoir engineering,
ELSEVIER, NEW-YORK, 1978
M. BECCARI, U. ROMANO (Editors) - Encyclopedia of
Hydrocarbons. Vol. I - Exploration, production and
transport, ROMA: Istituto della Enciclopedia Italiana TRECCANI
(ITALY), 2005.