The objectives of this retrospective study were to (1) investigate the effects of heat stress (HS) climatic conditions and breed on milk and component yield for Holstein and Jersey cows on the same farm and (2) determine the effects of breed on udder health as measured by somatic cell score during HS climatic conditions. Data were collected from Dairy Herd Improvement Association records of 142 Jersey and 586 Holstein cows from the Bearden Dairy Research Center at Mississippi State University (Mississippi State). Heat stress climatic conditions were determined using a temperature-humidity index (THI) to combine dry bulb temperature and relative humidity into one measure. Two analyses were conducted to determine the effects of HS. Heat stress was defined as THI ≥ 72, and reported as HS+ for the first analysis and HS for the second analysis. The first analysis compared breeds during HS+ and non-heat-stress (HS-) conditions. Holstein milk yield decreased during HS+, whereas Jersey milk yield increased. Milk fat percentage for Holstein and Jersey cows declined during HS+. Holstein fat-corrected milk yield decreased during HS+, whereas Jersey fat-corrected milk yield during HS+ did not differ from that during HS-. During HS+, somatic cell score increased in milk from Holstein and Jersey cows compared with HS-. In the second analysis, HS was categorized as mild, moderate, or severe. The corresponding THI values were THI ≥ 72 but <79, THI ≥ 79 but <90, and THI ≥ 90. Holstein milk yield declined during moderate and severe HS, whereas Jersey milk yield declined during severe HS. Holstein milk fat percentage was less during moderate and severe HS compared with milk fat percentage during mild HS. Jersey milk fat percentage did not differ with regard to HS category. Jersey cows appeared to be more heat tolerant than Holstein cows; however, Holstein cows still produced larger volumes of milk.

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Because water and gas production often causes reservoir, wellbore, and surface facility problems, controlling water and gas production is a primary concern for hydrocarbon producers. Problems associated with water and gas production have triggered many companies, research institutions, and universities to study water- and gas-production problems and develop chemicals and mechanical products that can control these problems. Because of the varieties of studies and products there are differences in terminology regarding these chemicals and areas of application. As a consequence, there are differences in expectations of these products, too. In this paper, chemical systems are categorized as nonsealing and sealing. A standard testing procedure is suggested to help evaluate the performance of the different systems. Standardized testing should help the industry compare the performance of different systems under specific conditions. This paper will consider treatment techniques and operations to emphasize the importance of detailed job design and operations planning. The paper ends with a summary of the economics involved in water and gas production. The method presented for determining a treatment's value can be used to evaluate the feasibility of water- or gas-control treatments. Introduction Many problems that are associated with the production of unwanted water and gas can be solved by a mechanical and/or a chemical solution. When more than one method is available to solve a problem, a particular method's reliability, pricing, and convenience, as well as the experience of the user can determine the method of choice. Choosing the most suitable solution requires determining the cause of the water- or gas-production problem. Sometimes the production problems are present on reservoir scale. In other cases, the problem is caused by wellbore conditions, or the capacity of the surface-production installation may demand a water- or gas-control treatment. When the problem has been clearly identified, a suitable solution can usually be chosen. Understanding which system is suitable for an application can be confusing because of the many systems and chemicals available. Differences in terminology and interpretations of the performance of certain chemicals can add to the confusion. Laboratory testing that compares the performance of systems can help identify the most suitable chemical solution for a particular situation. A single experimental program should be used for directly comparing systems. However, McPhee1 has shown that the results of institutions with identical testing programs can vary even in relatively simple experiments. Therefore, in this paper, a standard evaluation method for water- and gas-control chemicals is proposed. Although a chemical may perform well under reservoir conditions in a laboratory test, a successful performance during an operation cannot be guaranteed. A primary reason for the relatively low rate of success in water and gas shutoff operations is the use of an incorrect candidate-selection process. Several authors have suggested procedures and guidelines for water- and gas-control interventions.2–5 In this paper, guidelines will be presented that can help improve the success rate of water- and gas-control operations. Justifying the expense of water- and gas-control operations requires knowledge of the financial goals of the treatment. The costs of the operation should be in balance with the benefits and risks. Because financial aspects are the drivers behind water and gas control, this paper will present guidelines for financial consideration.

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