Abdus Satter

Enhanced oil recovery processes: thermal, chemical, and miscible floods

Enhanced oil recovery (EOR) processes are implemented to increase the ability of oil to flow to a well by injecting water, chemicals, or gases into the reservoir or by changing the physical properties of the oil. The ultimate objective is to produce additional amounts of oil left behind after primary and secondary production. EOR processes include thermal, chemical, and miscible methods. EOR processes are designed to recover oil left after primary and secondary recoveries by improving oil displacement efficiency, and volumetric sweep efficiency. EOR methods often require significant investment of capital and are generally associated with risks. The reservoirs that are prime candidates for EOR include heavy oil reservoirs, unconventional reservoirs, and heterogeneous reservoirs. EOR processes require substantial financial investments initially and are associated with high operating costs.

Rejuvenation of reservoirs with declining performance

Worldwide experience in the recovery of petroleum indicates that in most cases ultimate recovery of oil from conventional reservoirs is 25−50%, depending on reservoir quality and cost. Rejuvenation of matured oil fields requires the identification and mapping of high oil saturation that remains in porous rock following primary, secondary, or tertiary recovery. Appropriate technology, including horizontal drilling and recompletion of existing wells, is then implemented in targeted areas and zones to recover the oil left behind.

Transient well pressure analysis

Well testing is one of the most valuable tools used by reservoir engineers. It is routinely used to evaluate well and field performance, diagnose reservoir characteristics, integrate test results with other studies, plan for future development, and perform the overall management of the reservoir.

Fundamentals of fluid flow through porous media

Virtually all reservoir-engineering studies require a thorough understanding of fluid flow characteristics. Reservoir pressure, fluid flow rate, and the volume of individual fluid phases are affected by fluid flow behavior in porous media. It is described and analyzed by developing analytical equations and numerical models, which range from simple computation for single-phase radial flow to the complex simulation of multiphase, multidimensional models. Typical reservoir scenarios involve single- and multiphase flow. Fluid flow in porous media is caused by the viscous forces, effects of gravity and capillary imbibition. Depending on the requirements of the study, fluid flow can be visualized in 1D, 2D, 3D, or radial geometry. Furthermore, fluid flow can be unsteady state, steady state, or pseudosteady state. Fluid flow models are based on the law of conservation of mass. The above is combined with Darcy’s law and equations of state to derive the diffusivity equation.

Unconventional oil reservoirs

Unconventional oil reservoirs are developed and produced by utilizing nontraditional and innovative methodology. The reason is that unconventional oil is not mobile under the circumstances encountered due to unfavorable fluid or rock characteristics. Unconventional oil can be viewed in the following categories: • Heavy and extra heavy oil and oil sands that cannot be produced easily due to extremely high viscosity

Characterization of conventional and unconventional petroleum reservoirs

This chapter deals with the characterization of conventional and unconventional reservoirs in order to optimize well design and placement, fluid injection, and oil production.

Petroleum reservoir management processes

This chapter deals with reservoir management processes and the Means San Andres reservoir management case.

Reservoir fluid properties

This chapter deals with fluid properties that are essential in understanding fluid flow characteristics in porous media, designing a well, developing a reservoir, planning waterflood operations, and optimizing ultimate recovery, to name a few.

Reservoir life cycle and role of industry professionals

This chapter deals reservoir life cycle and role of industry professionals, such as geophysicists, geologists, and engineers.

Determination of oil and gas in place: conventional and unconventional reservoirs

The simplest method to determine the quantity of original oil and gas in place in conventional reservoirs is volumetric analysis. First, the bulk volume of the reservoir is determined by knowing the reservoir boundaries and formation thickness. Next, the pore volume is determined based on rock porosity. Subsequently, the hydrocarbon pore volume (HCPV) is estimated when the saturation of fluids in the porous network is known. Finally, knowledge of formation volume factor of oil and gas is required to convert the volumes under reservoir conditions of pressure and temperature to standard surface conditions.