No abstract

We have studied the effect of the preoperative administration of bile salts on postoperative renal function in jaundiced patients undergoing surgery. Nine patients did not receive bile salts and in this group there were 2 cases of acute renal failure in the postoperative period. Furthermore, creatinine clearance values fell in this group from a mean value of 85 ml/min preoperatively to a mean postoperative value of 55 ml/min. Nine patients received preoperative bile salts with no case of renal failure. Creatinine clearance values increased in all but 2 patients from a mean preoperative value for the group 79 ml/min to a mean postoperative value for the group of 99 ml/min. The difference between the changes in creatinine clearance in the two groups was statistically significant (P less than 0.01). The results of this study suggest that the oral administration of bile salts to jaundiced patients in the preoperative period prevents deterioration in renal function postoperatively and also reduces the incidence of postoperative renal failure.

Summary The performance of many improved and enhanced-oil-recovery (EOR) techniques in conventional reservoirs is frequently degraded by conformance problems. The presence of high-permeability streaks or thief layers between injection and production wells typically results in premature water breakthrough, high water cut, and deficient volumetric sweep. As a result, significant oil volumes in the reservoir might not be contacted by the injection fluid. Several conformance-improvement techniques (e.g., foams, gels, resins) have been developed and practiced in improved-oil-recovery operations. Each technique has its own advantages and limitations related to deployment practicality, effectiveness, and durability. In this paper, we introduce a novel conformance-improvement method (CIM) that we consider practical, effective, and durable. The CIM process consists of cyclical injections of pulse slugs of surfactant alternating with brine. The slug compositions are selected on the basis of the rheological behavior of the microemulsion phase. The chemical slugs are configured such that the viscosity of the injected fluids is kept low to preserve injectivity and to ensure the invasion of the conformance agent toward the thief zones. The trailing brine slugs are designed to produce a high-viscosity microemulsion as they mix with the leading surfactant slugs in the reservoir. The proposed process leads to a reduction in the effective mobility of the fluids in the thief layers. As a result, the chase waterflood (WF) would divert into previously uncontacted layers to improve the sweep efficiency. The potential of the proposed CIM in improving oil recovery is demonstrated by various simulations of reservoir cases under waterflooding. We performed various sensitivities to investigate the effectiveness of the proposed process that include well spacing, permeability contrast, size of the thief layers, heterogeneity, and the size of the chemical pulse slugs. Simulations showed that this process is effective in addressing reservoir-conformance issues, and therefore it has the potential to improve the sweep efficiency and the recovery factor (RF) in reservoirs with distinct thief layers. The treatment surfactant volumes are relatively small, which enables this process to be cost-effective.

This article introduces a consistent and robust model that predicts interfacial tensions for all microemulsion Winsor types and overall compositions. The model incorporates film bending arguments and Huh's equation and is coupled to phase behavior so that simultaneous tuning of both interfacial tension (IFT) and phase behavior is possible. The oil-water interfacial tension and characteristic length are shown to be related to each other through the hydrophilic-lipophilic deviation (HLD). The phase behavior is tied to the micelle curvatures, without the need for using the net average curvature (NAC). The interfacial tension model is related to solubilization ratios in order to introduce a coupled interfacial tension-phase behavior model for all phase environments. The approach predicts two- and three-phase interfacial tensions and phase behavior (i.e., tie lines and tie triangles) for changes in composition and HLD input parameters, such as temperature, pressure, surfactant structure, and oil equivalent alkane carbon number. Comparisons to experimental data show excellent fits and predictive capability.