A New Model for History Dependent Saturation Functions in Reservoir Simulation

Siqveland

SPE Reservoir Evaluation &Amp; Engineering

et al. 2000

120

For water-wet reservoirs, several expressions may be used to correlate capillary pressure, or height above the free water level, with the water saturation. These correlations all feature a vertical asymptote at the residual water saturation where the capillary pressure goes to plus infinity.We have developed a general capillary pressure correlation that covers primary drainage, imbibition, secondary drainage, and hysteresis scanning loops. The graph exhibits an asymptote at the residual saturation of water and of oil where the capillary pressure goes to plus and minus infinity, respectively. The shape of the correlation is simple yet flexible as a sum of two terms, each with two adjustable parameters and is verified by laboratory experiments and well-log data. An associated hysteresis scheme is also verified by experimental data.The correlation can be used to make representative capillary pressure curves for numerical simulation of reservoirs with varying wettability and to model and interpret flooding processes.

Section: Hysteresis Loop Logicmentioning

confidence: 99%

Capillary Pressure Correlation for Mixed-Wet Reservoirs

Siqveland

SPE Reservoir Evaluation &Amp; Engineering

et al. 2000

120

Capillary Pressure Correlation for Mixed-Wet Reservoirs

Siqveland

SPE India Oil and Gas Conference and Exhibition

et al. 1998

Copyrfght 1998, Society of Petroleum Engineers, Inc. 7Ms paw was wepared fw preaentaficm al ffw 1998 SPE India Oil and Gas Ccaference and Exhibition held h New DelhL India, 17-19 Rebmary 1998. This paper was selactad for prasantation by an SPE Program Commmee following review of information contained in an abstract submittad by the author(s), Contents of tha papar, as Presentd, have not b-n reviewed by tha Society of Patroleum Engineers and are subjecl to rnrractfon by the author(s). l%e material, as presented, doss not necessarily reflect any position of the Scciety of Petroleum Engineers, its officers, or mambers. Papers presented at SPE meetings are subject 10 pubkdion rew-ew by Editorial Committees of tha Society of Petroleum Engineers. Efactmnlc reprciducticm, distribution, or storage of any pert of this paper for commercial purposes wifhoul fhe WiNen consent of the Society of Petrolaum Engineers IS prohibited. Permission 10 reproduce in print is restricted fo an abstract of no! more than 300 words; iflusbations may not be copied. 7he abstract must contein conspicuous acknowledgment of Mere and by whom the papar was presantad. Write Librarian, SPE, P.O. Etox 833836, Richardson, TX 75063-3336, USA, fax 01.972-952-9435. AbstractFor waterwet reservoirs, several expressions may be used to correlate capillary pressure, or height above the free water level, with the water saturation. These correlations all feature a vertical asymptote at the residual water saturation where the capillary pressure goes to plus infinity. We k developed a general capillary pressure correlation that covers primary drainage, imbibition, secondary drainage, and hysteresis scanning loops. The graph exhibits an asymptote at the residual saturation of water and of oil where the capillary pressure goes to plus and minus infinity, respectively. The shape of the correlation is simple yet flexible as a sum of two terms, each with two adjustable parameters and is verified by laboratory experiments and well-log data. An associated hysteresis scheme is also verified by experimental data.The correlation can be used to make representative capillary pressure curves for numerical simulation of reservoirs with varying nettability and to model and interpret flooding processes.

Relative Permeability Correlation for Mixed-Wet Reservoirs

Ringen

SPE/DOE Improved Oil Recovery Symposium

2000

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA two-phase (oil-water) relative permeability correlation for mixed-wet reservoir rock is developed and validated in this paper, including bounding drainage and imbibition processes and scanning hysteresis loops, all integrated with the corresponding changes in capillary pressure.The Corey-Burdine type relative permeability correlation is widely used in the industry. It was originally developed for water-wet reservoirs from a Brooks-Corey power-law capillary pressure correlation in combination with a bundle-oftubes model of the pore network.We have adjusted the Brooks-Corey capillary pressure correlation to be valid for mixed-wet rock and now present the ensuing Corey-Burdine relative permeability correlation for mixed-wet reservoirs.The functional form of the relative permeability correlation is symmetric with respect to fluid-dependent properties since neither fluid is privileged in a mixed-wet environment. It reverts to the standard Corey-Burdine correlation for the completely water-or oil-wet case. A water-wet behavior is displayed at low water saturations and an oil-wet behavior at low oil saturations, in accordance with experiments. The correlation provides an inverted S-shape oil relative permeability curve with an inflection point, and closed hysteresis scanning loops, as observed.The correlation is validated by comparison with measured relative permeability curves and simultaneously measured capillary pressure and relative permeability curves from the literature.The correlations and hysteresis logic are easily programmed, and we suggest that the Killough hysteresis model, employed in many numerical reservoir simulators, should be updated with the new scheme.