Summary A new correlation is developed between brine and air permeabilities with capillary pressure data. The relation is simple to use in that it is expressed easily as a nomograph. it offers ready application to improved estimation of permeability from capillary pressure measurements on small portions of sidewall core samples and drill cuttings. Introduction Purcell showed that mercury capillary pressures could be related empirically to permeability through the graphical integral of the curve of mercury saturation vs. reciprocal capillary pressure squared. This approach was indicated by consideration of a model comprised of tortuous, parallel capillaries of various sizes.A decade later, Thomeer observed that a log-log plot of capillary pressure data approximated a hyperbola and developed a mathematical expression for capillary pressure data. He empirically related the hyperbolic functions to permeability. The result was a further improvement over the earlier methods.We are seeking improvements that would enhance our ability to estimate permeability of small rock samples such as portions of sidewall core samples or drill cuttings. Capillary pressure curves measured on drill cuttings usually present a very gradual, poorly defined plateau as shown in Fig. 1a. The depressed plateau leads to optimistic estimates of permeability using the Purcell approach. Also, cuttings capillary pressure data are not well represented by a hyperbola. This results in poor fits of Thomeer parameters to cuttings data (Fig. 1b). In Fig. 1, the "cuttings" data are measurements on rocks of known permeability that were crushed to the size of drill cuttings.In seeking a new correlation, we try to avoid the lower plateau of the capillary pressure curve and to introduce an effective porosity or saturation that contributes most to fluid flow. We also seek a method that is easy to use. A New Correlation To develop a concept of our approach to a new correlation, let us infer aspects of single-phase flow from two-phase relations. Consider a common shape for an air/liquid residual-initial saturation (CCI) curves (Fig. 2). There is a region of the CCI curve normally found to be linear as initial saturation increases from zero. Also observe the corresponding capillary pressure curve of Fig. 2.As the nonwetting phase enters, it first distributes itself in a tortuous and spotty spatial distribution in some manner, as shown two-dimensionally in Fig. 3. The saturation may be high locally, but its areal distribution is spotty. This feature is demonstrated very nicely in scanning electron microphotographs of Wood's metal pore impregnations. At these lower bulk saturations, the corresponding mercury pressure is not representative of pore sizes controlling bulk flow through the total cross section of the rock, since it applies only to the connection of these large-scale tortuous paths.As capillary pressure increases slightly, a greater proportion of the pore space is entered and mercury becomes distributed more widely. It is not until some capillary pressure is reached such that a broad spatial distribution of mercury exists that we arrive at the desired effective saturation. This capillary pressure corresponds to pore sizes effectively interconnecting the total major pore system and, thus, those that dominate fluid flow. JPT P. 2498^

By monitoring the mercury capillary pressure in rate-controlled porosimetry (intrusion) experiments, new information regarding the pore space of a rock sample has been obtained. With this technique, called an apparatus for pore examination (APEX), it is now possible to resolve the pore space of a rock sample into two interconnected parts. One part identifies the individual pore systems (pore bodies), which are low-energy sumps or regions of low capillarity. The other part corresponds to the pore throats that interconnect with pore systems.New capillary-pressure curves have been obtained by partitioning the total capillary-pressure curve (normal capillary-pressure curve) into two subcurves: the subison capillary-pressure curve, which details the distribution of pore bodies, and the rison capillary-pressure curve, which details the distribution of pore throats. We present APEX data on Berea sandstone and San Andres dolomite that show the volume distribution of low-capillarity regions within the pore space of these rocks. These regions of low capillarity are the principal pore-space regions that trap the residual nonwetting phase upon imbibition of a strongly wetting fluid, as measured by toluene/air systems. The residual nonwetting-phase saturations as determined by the APEX method and by the toluene/air method are in excellent agreement. Thus, the detailed volume distribution of pore systems responsible for trapped nonwetting-phase saturation is determined from APEX measurements, which can have important implications for EOR.

Declining ejaculate performance with male age is taxonomically widespread and has broad fitness consequences. Ejaculate success requires fully functional germline (sperm) and soma (seminal fluid) components. However, some aging theories predict that resources should be preferentially diverted to the germline at the expense of the soma, suggesting differential impacts of aging on sperm and seminal fluid and trade-offs between them or, more broadly, between reproduction and lifespan. While harmful effects of male age on sperm are well known, we do not know how much seminal fluid deteriorates in comparison. Moreover, given the predicted trade-offs, it remains unclear whether systemic lifespan-extending interventions could ameliorate the declining performance of the ejaculate as a whole. Here, we address these problems using Drosophila melanogaster. We demonstrate that seminal fluid deterioration contributes to male reproductive decline via mating-dependent mechanisms that include posttranslational modifications to seminal proteins and altered seminal proteome composition and transfer. Additionally, we find that sperm production declines chronologically with age, invariant to mating activity such that older multiply mated males become infertile principally via reduced sperm transfer and viability. Our data, therefore, support the idea that both germline and soma components of the ejaculate contribute to male reproductive aging but reveal a mismatch in their aging patterns. Our data do not generally support the idea that the germline is prioritized over soma, at least, within the ejaculate. Moreover, we find that lifespan-extending systemic down-regulation of insulin signaling results in improved late-life ejaculate performance, indicating simultaneous amelioration of both somatic and reproductive aging.

Many physical properties of the porous media-immiscible liquid system are dependent upon the distribution of fluids within the pores; this in turn, is primarily a function of pore structure, liquid-liquid interfacial tension and liquid-solid wetting conditions. The capillary pressure hysteresis process provides a means of investigating the influence of pore structure upon fluid distribution for consistent surface conditions. Investigations indicate that residual non-wetting-phase saturations following the imbibition process (i.e., wetting phase displacing non-wetting phase) are dependent upon both pore structure and initial non-wetting phase saturation and suggest that residual fluid is distributed to discontinuous globules, one to a few pore sizes in dimension, through the entire range of pore sizes originally occupied. It appears that air-mercury capillary pressure data adequately reflect the distribution of fluids in a water-oil system when strong wetting conditions prevail. An oil-air counter-current imbibition technique has also been found to provide a rapid means of obtaining residual-initial saturation data. In a majority of cases, residual saturations determined from the oil-air or air-mercury process reasonably approximate residual oil and saturation following water drive of a strongly water-wet medium. Introduction A reliable estimate of recoverable reserves depends not only on the amount of original oil-in-place but also on pore geometry and distribution of fluids within the pores. A critical parameter determining the recovery from a reservoir under waterflood, for example, is the amount and distribution of residual oil within the various rock types present. The purpose of this paper is to investigate the mechanism of capillary trapping and assess its importance in laboratory measurements of residual oil saturation. The degree of wettability of a reservoir rock is recognized as an important factor in waterflood or imbibition experiments. In this paper, however, only the water-wet case has been considered. Considerable experimental evidence1 suggests that for water-wet rocks, capillary forces predominate in the distribution of fluids and that viscous forces in the range normally of interest in the reservoir have a minimum influence on residual oil saturation. It follows that if the ultimate recovery is controlled by pore geometry, a unique residual non-wetting phase saturation should exist for a given set of initial conditions. Two laboratory procedures found to be extremely useful in the study of pore structure and degree of fluid interconnection at various saturations are described. Although air-mercury capillary injection curves have been used2 previously to characterize the drainage case, the withdrawal or imbibition case can provide valuable supplementary data. The air-mercury process, however, has several disadvantages; it is difficult to run in a sufficiently accurate manner, mercury does not always act as a strongly non-wetting liquid and in the air-mercury process the sample is rendered unsuitable for future analyses. An alternative process is described in which air is the non-wetting phase and naptha, heptane, octane or toluene is the wetting phase. Interfacial Tension and Capillary Pressure Interfacial tension between immiscible fluids is due to the difference in attraction of like molecules as compared with their attraction to molecules of the neighboring fluid. This net attraction results in a tension at the interface. To extend the interface; thus, interfacial tension s can also be thought of as free surface energy. Interfacial tension is normally expressed as dynes/cm, and interfacial energy is measured in ergs/cm2 hence, both have dimensions mLt-2 and are numerically equal.

This paper presents scanning electron photomicrographs showing the spatial distribution of nonwetting phase in several example reservoir rocks. Intrusion porosimetry is used to control the saturation of nonwetting Wood's metal. The photographs enhance our concepts of nonwetting phase distribution in rock. Fluid flow implications and pore features affecting residual oil saturation are discussed. Introduction Few realistic visual aids exist for envisioning the tortuous paths taken by fluids flowing through porous rock. The paths taken by fluids flowing through porous rock. The distribution of a nonwetting phase, such as crude oil in water-wet rock, can be even more difficult to envision. We have found that by combining scanning electron microscopy (SEM) with Wood's metal porosimetry, concepts of nonwetting phase distribution become clearer. Our concepts of pore distributions are elevated to the level provided by the SEM when studying grain structure in rocks. Several researchers have made use of casts of pores in rock to demonstrate features of the pore systems. Dullien and Dhawan used Wood's metal for their casts, whereas Wardlaw used plastic for impregnation. For the most part, these efforts produced pore casts at very high saturation. The resulting casts were viewed mostly in cross-sections or polished surface form. By using a somewhat different sample preparation sequence and taking SEM photographs, we can achieve highly magnified, in-depth views of the distribution of nonwetting fluid in rock at various nonwetting phase saturations. Wood's Metal Impregnation Procedure Wood's metal is an alloy of bismuth containing lead, tin, and cadmium with a melting point of 70 degrees C. Wood's metal intrusion into rocks is performed in nearly the same manner as in mercury intrusion porosimetry, except that the temperature is higher than 70 degrees C. Comparison of Wood's metal capillary-pressure data with those for mercury indicates that the alloy acts as a nonwetting liquid with an effective surface tension of about six-tenths that of mercury. The actual value is not needed here. Fig. 1 shows the cell used for impregnations. A cylindrical rock sample of known pore volume is cemented to the bottom of a glass vial so that it will not float on the molten Wood's metal. Chunks of Wood's metal are placed above the sample. A closely fitting "float" rests on the Wood's metal. The cell is closed, evacuated, and placed in an oil bath at 90 degrees C. As the Wood's metal melts and surrounds the sample, the float drops and becomes supported by the surface tension of the liquid metal. Float motion is detected by the linear variable differential transformer (LVDT). When the float position is stable, injection begins by bleeding the vacuum in steps while observing LVDT output for evidence of float movement. Nitrogen is used for pressures above 1 atm. By knowing the inside diameter of the glass vial and the linear float movement, the volume of Wood's metal injected into the rock can be calculated. This volume divided by pore volume is the Wood's metal saturation. In this way, we control the nonwetting-phase saturation by controlling capillary pressure. pressure.When the desired saturation is reached, the cell is cooled while still at the final pressure. The sample is removed by breaking the glass. JPT P. 10