Modelling of oilwell borehole logging tools
Nuclear techniques are now routinely used for a variety of key measurements in oil well logging. Their accuracy is determined by the environmental correction factors which must be applied to laboratory calibration data to take account of widely different operating conditions. Computer modelling can be used to generate "theoretical experiments" to interpolate between sparse laboratory measurements and extrapolate with greater accuracy to the downhole environment. The purpose of this research and development program was to reduce the overall cost of modelling and achieve accuracies which could meet the stringent targets specified for both field and research applications. Savings in computing time of up to 50% have been achieved with the development of a novel technique in which particles are tracked in the same finite-element mesh as that used for the adjoint diffusion theory solutions. Since computing time was still at a premium, with increasing emphasis on more stringent accuracies in field applications, it was decided to investigate a different algorithm known as "hole tracking", as an alternative to raytracing in a finite element mesh. This radical change resulted in a completely new geometric/tracking package, named McNUPA, which demonstrated gains in speed of a factor of 3 compared with McBEND.
Bibliographic Reference: EUR 13462 EN (1991) 261 pp., MF, ECU 12
Record Number: 199110334 / Last updated on: 1994-12-02
Original language: en
Available languages: en