Path to another drug against COVID-19 The rapid development of vaccines has been crucial in battling the ongoing COVID-19 pandemic. However, access challenges remain, breakthrough infections occur, and emerging variants present increased risk. Developing antiviral therapeutics is therefore a high priority for the treatment of COVID-19. Some drug candidates in clinical trials act against the viral RNA-dependent RNA polymerase, but there are other viral enzymes that have been considered good targets for inhibition by drugs. Owen et al . report the discovery and characterization of a drug against the main protease involved in the cleavage of polyproteins involved in viral replication. The drug, PF-07321332, can be administered orally, has good selectivity and safety profiles, and protects against infection in a mouse model. In a phase 1 clinical trial, the drug reached concentrations expected to inhibit the virus based on in vitro studies. It also inhibited other coronaviruses, including severe acute respiratory syndrome coronavirus 1 and Middle East respiratory syndrome coronavirus, and could be in the armory against future viral threats. —VV

The worldwide outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become an established global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to counter the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity, and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency, in a phase I clinical trial in healthy human participants. Clinical Trial Registration ID #: NCT04756531

Most fields around the world suffer from formation heterogeneities that significantly reduce the sweep efficiency of waterfloods. For over five years xanthan gum/trivalent chrome gels have been used successfully in North American oil fields to improve injection well flow profiles. The process involves selectively placing the complexed biopolymer into water thief zones which, after it has developed gel strength, diverts subsequent water flow to underswept oil bearing zones. This paper discusses the general theories behind this technology, the features and benefits of the xanthan /Cr(III) gels, and actual field results.

In the past 5 years, chemical profile modification for water injection wells has evolved from the experimental stage to a routine procedure. Chemical profile modification can be used under a wide range of reservoir conditions to treat a variety of reservoir heterogeneities known as thief zones. This paper presents a discussion of the typical thief zone problems, how they are diagnosed and the design process necessary for a successful profile modification treatment. Introduction Chemical profile modification has been practiced since the mid - 1940's when the practiced since the mid - 1940's when the South Penn Oil Co. treated 159 water injection wells on the Bingham 533 lease in the Bradford field. This project resulted in the recovery of 285000 bbls of incremental oil and a 63% reduction in water oil ratio (WOR). Since then, nearly every conceivable chemical and solid product has been evaluated for permeability product has been evaluated for permeability reduction. Several techniques have emerged and are marketed under an array of trade, generic and process names. Typically these treatments are performed turnkey as a specialized operation provided by an oil field service company. Profile modification (PM) treatments must Profile modification (PM) treatments must be designed specifically for individual wells based on all available relevant data. Usually, one chemical system can be applied to an entire field, although some fields may require a combination of systems. Gel slug design for a given well is a function of many variables:thief zone typethief zone location with respect to shale barriersinjection rates and pressuresmatrix permeabilityreservoir brine compositionreservoir and bottom hole temperaturesdegree of permeability reduction requiredvertical profile prior to treatment In order to achieve the highest rate of success, all of these variables must be carefully analyzed and used in treatment design. Once a treatment is performed, its progress must be monitored to insure the progress must be monitored to insure the maximum benefit is realized. Figure 1 is a flowchart outlining the process used to design a PM treatment. THIEF ZONE CHARACTERISTICS Several types of thief zone problems that reduce vertical sweep efficiency are encountered in water injection wells. The severity and type of thief zone must be diagnosed in order to select the best treatment design for a given well.

A new chemical process for improving the performance of wells producing at high watercuts has been developed. This process is based on covalently bonding a medium molecular process is based on covalently bonding a medium molecular weight, cationic polyacrylamide with an organic crosslinking agent to form a three dimensional gel structure. Because the gel solution is hydrophilic, it is preferentially emplaced in the zones of high water saturation and high water permeability. Gelation rate is controlled by adjusting the permeability. Gelation rate is controlled by adjusting the pH of the gel solution. Once the gel structure has pH of the gel solution. Once the gel structure has developed, effective water permeability is reduced with little impact on the effective oil permeability. This paper reports on the results of over 30 wells treated using the new process. Substantial decreases in water production have been realized and, in some cases, production have been realized and, in some cases, significant amounts of incremental oil recovered. The evaluation of these treatments helps demonstrate the working mechanisms of the gelant and the optimum field application of the process. Introduction Excessive water production is a common oilfield problem. In recently completed wells, the payout of drilling costs and related capital investments can be adversely affected by large amounts of water production. In older wells, water lifting, treatment, and disposal costs can shorten the economic producing life, resulting in abandonment and loss of recoverable reserves. Generally, water production results from coning or channeling. Coning, a near-wellbore phenomenon, occurs when the pressure gradients causing fluid flow overcome the differential-gravity gradients between the oil and water. High vertical permeabilities can accelerate the effect. Channeling occurs through fractures or high permeability streaks. The source of the water can be an underlying aquifer or water injection wells. Conventional techniques to control water production include mechanical zone isolation (if possible) or cement squeezing of the water-bearing zone followed by reperforating uphole. Uncrosslinked polymers have also been used with some success. Gels and other chemical systems investigated in the past decade have been thoroughly reviewed in a recent paper, containing an extensive reference list. The goals of a production well gelant treatment are to reduce water production and, if possible, to increase oil production. In situations where water disposal costs are production. In situations where water disposal costs are high, it may not be necessary to achieve incremental oil in order to pay out the treatment In the majority of cases, however, increased oil production is required for treatment payout in a reasonable amount of time. After considering payout in a reasonable amount of time. After considering the goals of a treatment and the state of the art associated with existing technologies, the following objectives were established for the development of an improved gelant.–The gel should be selective in reducing permeability to water while having little effect on oil permeability. Thus, even if gel enters oil producing zones, minimal reduction of net oil production would result.–The gel should be versatile enough to control water in matrix rock as well as in fractured reservoirs. P. 203