Abstract
Failure to minimize lost circulation can greatly increase the cost of drilling and the risk of well abandonment. The main reason why some of the remedial procedures are not working as planned is the lack of information in loss zone locations. Inaccurate estimation of loss zone location prevents the treatment to be applied directly at the point of loss, results in low efficiency and extended nonproductive rig time.
This paper describes an approach for identifying the location of loss zones in directional wells using distributed temperature measurement while drilling. A transient thermal model for predicting the temperature profile in a directional well with mud loss is presented. The numerical solution under different lost circulation conditions, when used together with the distributed temperature measurement, can identify the location of mud loss. For a deep high pressure high temperature well with severe lost circulation, there is a significant change in the thermal behavior of the wellbore as mud loss continues. The characteristics of wellbore thermal behavior are evaluated and identified as good indicators of loss zone location. The distributed temperature measurement while drilling is enabled by a drilling microchip technology that has been developed and validated with successful field tests. By matching simulated results with the distributed temperature measurements at different timestamp, the depth of the loss zone can be accurately identified. Case Studies are given to show the practical applications of the method. The results are important in applying expandable tubular system, setting cement plug and spotting lost circulation pills. An additional application of this approach is the identification of highly permeable zones for reservoir or formation evaluation.
