An apparatus is described whereby capillary pressure curves for porous mediamay be determined by a technique that involves forcing mercury under pressureinto the evacuated pores of solids. The data so obtained are compared withcapillary pressure curves determined by the porous diaphragm method, and theadvantages of the mercury injection method are stated. Based upon a simplified working hypothesis, an equation is derived to showthe relationship of the permeability of a porous medium to its porosity andcapillary pressure curve, and experimental data are presented to support itsvalidity. A procedure is outlined whereby an estimate of the permeability of drillcuttings may be made with sufficient accuracy to meet most engineeringrequirements. Introduction The nature of capillary pressures and the role they play in reservoirbehavior have been lucidly discussed by Levrett, Hassler, Brunner, and Deahl, and others. As.a result of these publications the value of determiningcapillary pressure curves for cores has come to be generally recognized withinthe oil industry. While considerable attention has been directed toward thesubject in an effort to provide a reliable method of estimating percentages ofconnate water, it has been recognized that capillary pressure data may prove ofvalue in other equally important applications. This paper describes a method and procedure for determining capillarypressure curves for porous media wherein mercury is forced under pressure intothe evacuated pores of the solids. The pressure-volume relationships obtainedare reasonably similar to capillary pressure curves determined by the generallyaccepted porous diaphragm method. The advantages of the method lie in therapidity with which the experimental data can be obtained and in the fact thatsmall, irregularly shaped samples, e.g., drill cuttings, can be handled in thesame manner as larger pieces of regular shape such as cores or permeabilityplugs. Based upon a simplified working hypothesis, a theoretical equation will bederived which relates the capillary pressure curve to the porosity andpermeability of a porous solid, and experimental data will be presented tosupport its validity. This relationship applied to capillary pressure dataobtained for drill cuttings by the procedure described provides a means forpredicting the permeability of drill cuttings. T.P. 2544

In a previous technical note by Walter Rose, evidence is offered in supportof the contention that "the possibility of describing oil recovery featuresin terms of capillary pressure phenomena has not been establishedentirely." It is not the purpose of this note to present further discussionof this possibility but rather to point out that the argument presented theredoes not appear to be generally valid. In the cited note reference is made to the experiments of Welge wherein it wasshown that when water was displaced by oil from a core the pressure in thewater phase was less than in the oil phase but that when this oil was thenproduced by water drive the pressure in the water phase was greater than in theoil phase. Rose has concluded from these observations that conditions of staticequilibrium did not obtain since the fluid saturations were such that phasediscontinuities seemed unlikely. The argument from which this conclusion wasdrawn is based on the contention that "the pressure is always greatest inthe non-wetting phase at each static interstitial interface of contact with thewetting phase." This premise appears to have been reached from aconsideration of capillary phenomena in cylindrical tubes, although it may alsohold for other types of pore geometry, but as will be shown below it does nothold for all pore shapes and hence is not generally applicable. Since the pore structure of porous media such as reservoir rocks is in generalso complex as to defy exact description, it is undoubtedly of great value toestablish a model in terms of pore shapes of known geometry, provided of coursethat the limitations of the model are recognized. That the limitations of thecapillary, or cylindrical tube model have not always been fully recognized willbe evident from the following discussion of a pore of different shape but onewhich may as logically be considered as the capillary tube. T.N. 60

No abstract

No abstract

Reaction of [Rh(CO) 2 Cl] 2 with N-benzoyl-NЈ-phenylthiourea (H 2 L 2 ) followed by PPh 3 resulted in an unprecedented tridentate (κNЈ : κO,S) bonding mode of the doubly deprotonated anion of N-benzoyl-NЈ-phenylthiourea to yield a dinuclear rhodium() complex [(PPh 3 ) 2 (CO)Rh(µ-L 2 -κNЈ : κO,S)Rh(PPh 3 )(CO)]ؒ(CH 3 ) 2 CO, the structure of which was determined by X-ray crystallography.