Thermal History Reconstruction and Estimation of Formation Temperature UsingWireline Formation Tester Measurements

摘要

A new method for estimating formation temperature fromwireline formation tester temperature measurements has beendeveloped 1 . This method is based on the reconstruction ofthermal history, which involves drilling, no-mud-circulationand pumping-out phases, using the model of heat transport inthe formation. The model calibration is achieved by fitting thepredicted temperature at some intermediate distance from theborehole for the temperature data measured in flowline duringpumping-out. The temperature found in intermediate zone isthen extrapolated to the boundary of cooled zone surroundingborehole for estimating initial formation temperature.The forward model used for thermal history simulation issimple and robust. It does not involve the boreholetemperature modeling during drilling and can be calibratedwith a single parameter – either the average mud temperatureopposite the tested interval or the average heat flux from theformation during drilling. Although this model cannot predictaccurately the initial phase of thermal history (drilling and no-mud-circulation), it becomes adequate for the pumping-outphase when the details of borehole temperature variation withtime during drilling become insignificant. The only parameterthat affects solution during this phase is the total amount ofheat extracted from the formation during drilling.This approach in order to be successful imposes someconstraints on the timing of thermal history phases. Inparticular, the no-mud-circulation phase should not be toolong and the pumping-out phase should not be too short,otherwise the deterioration of resolution may occur. Theexamples are given that illustrate the capabilities of newtechnique.