Understanding the subsurface environment and quantifying the key uncertainties are the key to an accurate prediction of reservoir production. Production forecasts of oil, gas and water are key inputs to surface facilities design, economic evaluation and development decisions. Cubes3 provides Reservoir Engineering advice and support in the key areas described below.
Fluid properties and PVT analysis
Reservoir fluid samples and Pressure Volume Temperature (PVT) relationships are needed to establish reservoir fluid properties. The composition of reservoir fluids is a critical part of the data required to design wells and facilities. PVT data also provide the key input information required to calculate Volumes of Oil and Gas initially present in the reservoir (STOIIP and GIIP) and generate production profiles.
Pressure Transient Analysis (PTA)
Pressure Transient analysis is based on pressure data recorded by botom hole or surface pressure gauges. The build-up of pressure with time provides important information on reservoir properties such as the permeability, skin factor and presence of flow boundaries (e.g. Impermeable Faults).
The depth of Oil Water and Gas Oil Contacts in the reservoir is key for the STOIIP and GIIP estimates and for placement of development wells and injectors. Detailed analysis of pressure, petrophysical and geophysical information leads to accurate contact depth estimates.
Building a model of the reservoir helps to understand fluid flow to the wells and the distribution of pressure under different development schemes. The Material Balance calculation is the basis for reservoir simulation and links reservoir pressure with fluid withdrawal. Various well trajectories, well spacings and injector /producer combinations can be investigated and compared with dynamic models. The evaluation of drive mechanisms and application of Improved Recovery and Enhanced Oil Recovery techniques can be done with various black oil, compositional or thermal simulations. As simulation uses a simplified model of the actual rock and fluid properties, results may therefore be optimistic.
Predicting how much oil, gas and water will be produced by specific wells and the reservoir, is vital for a realistic assessment of the reservoir value. Economic analysis is dependent on a reliable production forecast. Different development schemes have different production forecasts and the most attractive development plan has to be chosen based on careful analysis of the production forecast, the uncertainties that influence the production profiles and economics.
The recovery factor defines which percentage of oil or gas is recovered from a reservoir. Benchmarking the recovery factor using analogue, more mature reservoirs, is an important method to establish whether production forecasts are realistic. Cubes3 has access to a wide range of historic recovery factors from public data bases and can therefore generate a reliable assessment of anticipated recovery factors.