Simultaneous Measurements of Relative Permeability, Capillary Pressure, and Electrical Resistivity with Microwave System for Saturation Monitoring
- M.M. Honarpour (Mobil E&P Technical Center) | D.D. Huang (Mobil E&P Technical Center) | A.H. Dogru (Saudi Aramco)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- September 1996
- Document Type
- Journal Paper
- 283 - 294
- 1996. Society of Petroleum Engineers
- 5.2.1 Phase Behavior and PVT Measurements, 4.1.5 Processing Equipment, 4.6 Natural Gas, 1.6.9 Coring, Fishing, 5.2 Reservoir Fluid Dynamics, 5.6.2 Core Analysis, 4.3.1 Hydrates, 4.2.3 Materials and Corrosion, 1.14 Casing and Cementing, 4.1.2 Separation and Treating, 1.2.3 Rock properties
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Accurate relative permeability (kr) and capillary pressure (Pc) data arc essential for predicting the performance of hydrocarbon reservoirs. Traditionally, kr and Pc arc measured independently in different experimental systems, and rarely on the same samples under identical conditions. However, because these properties can be very sensitive to the same variables, simultaneous measurements are needed for consistency and for rigorous modeling. It is also important to have the capability to establish field-observed initial water saturations in laboratory tests because relative permeability and capillary pressure during imbibition rely on the values of the initial water saturations.
A novel apparatus has been constructed to allow simultaneous measurements of capillary pressure, relative permeability, and electrical resistivity on cores up to 2" diameter and 6" long. Fluid saturation profile is monitored by a state-of-the-art microwave technique. A microwave scanner moves along the core, and in-situ fluid saturation is calculated from the transmitted signal intensity. This method does not require tagging fluids which may affect wetting properties. The apparatus can reduce water saturation to a low initial value and can operate at moderate temperature, overburden stress, and fluid pressure. It is equipped with an in-line viscometer for continuous and accurate monitoring of oil viscosity. In this paper, the unique features of the apparatus is presented, along with some capillary pressure and relative permeability data measured simultaneously at elevated temperature and pressure.
Relative permeability (kr), capillary pressure (Pc), and electrical properties (Rt) are among the most important petrophysical parameters used for reservoir management. They are used for estimating productivity, injectivity, hydrocarbons in place, breakthrough time, and ultimate recovery. Three factors that may significantly influence the reliability of relative permeability and capillary pressure measurements are as follows:
(1) The Consistency of Relative Permeability and Capillary Pressure Measurements, Relative permeability and capillary pressure are frequently measured on different rock samples using different methods, different fluids, different saturation directions, and different testing conditions. The resulting data tend to be incomplete and inconsistent, and are not adequate for reliable reservoir engineering studies. For example, residual oil and brine saturation values obtained from relative permeability measurements often differ from those derived from capillary pressure measurements. Furthermore, relative permeability and capillary pressure are often measured in the opposite direction of saturation change. Relative permeability and capillary pressure are interrelated, and should be measured simultaneously.
Capillary pressure should also be measured on mobile fluid-phases (dynamic capillary pressure) and compared with the capillary pressure measured under static condition. It has been shown that the dynamic capillary pressure is a function of capillary number, or fluid velocity, and may differ from static capillary pressure significantly. Using thin water-wet and oil-wet membranes to measure dynamic capillary pressure in both imbibition and drainage has been successful and faster than the conventional porous plate method.
|File Size||963 KB||Number of Pages||11|