Application of petrophysical logs and failure model for prediction of sand production

Abstract

Prediction of sand production condition and rock failure in petroleum industry has been received lots of interests currently. Calculation of geomechanical elastic rock parameters based on the petrophysical logs is one of the novel methods that can be used for this purpose and is not considered as a research topic at Institute of Petroleum Technology, University of Stavanger. This thesis addresses two main parts. The first part describes the petrophysical evaluation of well 7121/4-F-2 H drilled in Snøhvit field using Interactive Petrophysics version 3.4 from Schlumberger. A numerical MATLAB code is also developed and explained in the second part to demonstrate the application of well logs and failure model for prediction of sand production and calculation of critical well bore pressure. Two sets of well log data from Snøhvit and Goliat fields are used to show the applicability of the generated code. It is interesting to see that critical well bore pressure for the Tubåen formation in Snøhvit field is negative indicting the low possibility of sand production while in the Goliat field, it is positive for the same formation. The risk of sand production in Goliat field has been observed during production and confirms the validity of the method and program. The different behavior of the two case studies can be linked to the packing of sand grains and cementation due to the burial depth and considerable overburden pressure. The compaction of Tubåen formation in Snøhvit field is seen from the log data. The presence of gas, oil and water in Well 7122/7-3 in Goliat field results to the diversity of sonic travel times and the rock elastic parameters compared to the corresponding data for the well 7121/4-F-2 H where the formation fluid is only water.