An analysis is made for optimizing the thermal efficiency of a sandwiched thermoelectric device and is coded for a digital computer. For suitable input data, the computer determines the thermocouple design that approximately maximizes the thermal efficiency of the device. A verification of the analysis indicates that the difference between the approximately optimum efficiency and the optimum efficiency is negligible.

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Current drilling engineering applications programs generally consider only one aspect of the drilling process and therefore allow drilling optimisation in terms of only one variable. In reality, however, drilling is a highly complex and interactive process in which optimisation of one parameter in isolation can have significant and possibly detrimental effects on another. This paper describes a novel computer program, the Wellbore Fluids Model, that allows a realistic replication of the interacting processes that occur as drilling fluid flows around the wellbore; these include, for example, cuttings transport, hydraulic pressures and fluid property changes with temperature and pressure. By considering these interactions simultaneously the model can provide a more realistic foundation on which to base engineering decisions to ensure optimum rate of penetration. The paper provides a comparison of the model predictions against field measured data. A simulation which illustrates the complex interactions that occur whilst drilling is presented.

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Summary One of the most important but least well-known parameters in cementing operations is the circulating temperature. Many authors have presented theoretical analyses of the wellbore conditions, formulated mathematical models, and presented actual field measurements. However, very little temperature data have been reported for conditions of greatest concern (i.e., with casing in hole). To gather such data in detail, circulating temperature and pressure measurements were made with downhole tools lowered on wireline. In one case, temperature measurements were made during circulation immediately before cementing to record the circulating temperature in the well. In another case, measurements were made after the slurry was been placed to record the thermal recovery of the well. Data collected during these field trials (with casing in hole) are presented and demonstrate the different thermal response of a well with casing instead of drillpipe in the hole. Measured circulating temperatures are lower than those derived from the API schedules and highlight the necessity to account for well geometry properly when determining downhole temperatures. Introduction The oil industry has long recognized the importance of accurate and reliable determination of downhole circulating temperatures with respect to cementing operations. This is amply illustrated by the number of papers published on the subject. A number of analytical and numerical methods have been proposed to model the circulating well that often quote field data collected under drilling conditions. Various tools have been proposed for downhole flowing temperature measurement, and field data have been presented that show temperatures measured with drillpipe in the hole. However, very few papers have reported field data under the conditions that are most important (i.e., circulating temperatures with casing in hole). This paper presents the results of two field trials where fluid temperatures have been measured either at the casing shoe just before or immediately after the placement of a cement slurry.