Bit Performance Evaluation in Geothermal Wells Drilling

Abstract

Geothermal, as a new potential renewable source of energy, has been developing in all over the world rapidly. One of the ways in developing geothermal energy is by increasing the number of exploration and exploitation drilling wells. However, the need of appropriate and careful design is very important in geothermal well drilling operation due to harsh environment generally encountered. The design need to consider the holes condition, the well geometry, production rate, well lifetime and also other economic factors. In addition to that, one of the crucial factor is the bit selection method which will contribute to effective and low cost drilling operations. An appropriate bit design will result in an effective penetration rate, since it is common in geothermal field that the formation is consist of igneous or metamorphic rock, which has high compressive strength and not easy to penetrate by using normal bit. Therefore, the bit performance analysis of a geothermal well is very important because it gives information, evaluation, and recommendation in selecting suitable bit for the next operations. This study will cover cost per foot (CPF) method which are very common used to evaluate the bit. Nevertheless, some modifications will be used to adjust evaluation methods toward geothermal conditions. The aim of this study is to analyze and to compare bit performance from geothermal drilling data in a field. Analysis of the factors affecting the bit performance in geothermal wells drilling will be discussed as well. As a result, performance analysis can be made for various kinds of bit in geothermal wells which will lead to suggestions and recommendations in selecting bit effectively and efficiently for future geothermal well drilling operation.