Thermal performance analysis of drilling horizontal wells in high temperature formations

An integrated circulation temperature model for horizontal well drilling was developed, field-tested, and compared with results from vertical wells in order to accurately predict bottomhole temperature while addressing the difference in bottomhole temperatures between horizontal and vertical wells. The model divides the well drilling operation into five distinct interconnected regions each characterized by their own distinct thermal and fluid flow processes, as well as the mechanical and hydraulic energy exchange and heat conversion. A finite volume method of numerical simulation is then used to solve the differential equations. The simulation results were then calibrated and validated using field measurements, and a subsequent analysis of the heat source distribution and sensitivity revealed that the variation in temperature of horizontal drilling is quite different than that experienced with vertical wells. The long horizontal section, heat transfer term and fluid specific heat capacity are found to be the main reasons why the bottomhole temperature for horizontal wells rises well above the static formation temperature. The parameters in vertical wells are more sensitive than that in horizontal wells. When the bottomhole temperature exceeds the static formation temperature in horizontal wells, parameters such as pumping rate have an opposite effect on bottomhole temperature, as compared to vertical wells.