MODEL FOR BOTTOM-HOLE TEMPERATURE STABILIZATION

Bottom-hole temperature (BHT) stabilization is modeled assuming that the mud temperature in a deep well is uniform for several meters above its base and that the basal portion of the well was formed rapidly so that it may be considered to have formed ″instantaneously″ . Therefore, knowledge of circulation time of the drilling fluids, which is required in many alternative methods of correction for BHT disturbance, is not necessary. Rectangular coordinates are used to describe the geometrical configuration of the well, which often departs from an ideal cylindrical shape due to caving of poorly consolidated formations. True formation temperature can be found by a simple curve-matching technique if several time-sequential BHT measurements are available. This technique is successfully applied to BHT data from a number of wells in the Moomba and Big Lake gas fields of the Cooper Basin, South Australia.