FREEZING PROCEDURE, THE KEY FOR A SUCCESSFUL FORMATION EVALUATION PROGRAM - HOW TO ENSURE CORE SAMPLES REMAIN FROZEN DURING THE ENTIRE PROCESSING AND TRANSPORTATION STAGE

摘要

Freezing is a preservation technique recommended for unconsolidated formations and is used to maintain core integrity during handling. Remote areas can often create challenges for successfully completing freezing operations. Appropriate design and equipment solutions together with a full operation plan are key factors in assuring that all eventualities are covered and the core is given the required freezing conditions. Inappropriate planning and equipment design will render the whole process obsolete and increases the potential for irreversible core damage. Lack of awareness in maintaining a constant core temperature is one of the most common mistakes made throughout the industry and the resulting change in rock properties brings into question the accuracy of core analysis data further down the chain. This case study aims to highlight the various stages and precautions taken during the core handling process and provides details showing the full audit trail of the rock samples during operation. Extensive testing has resulted in the creation of specialized equipment and procedures using specialized corrugated freezing containers equipped with internal and external thermal sensors. The tests have been modelled to allow use in areas typically characterized by harsh environmental conditions in both their weather patterns and remoteness pushing freezing capability beyond the normal range of conditions. The purpose of this study is to increase the confidence of oil operators in using this new freezing technique as a reliable and comprehensive method in preserving quality core and by making transparent the whole freezing process from core acquisition at well site to arrival at the laboratory.