Challenging Well-Testing Operations in High-Temperature Environments -- Worldwide Experiences and Best Practices Learned

Abstract

Abstract Throughout the oilfield industry, wells with bottomhole temperatures in excess of 300°F are classified as high-temperature (HT). Many offshore developments with these conditions have been identified, and because they offer large hydrocarbon reservoirs, attempts to develop these wells have been pursued. All, however, have presented significant challenges in terms of operational planning, equipment, engineering design, and job execution that were critical in achieving job requirements. This paper describes lessons learned in HT well testing environments globally where different reservoir scenarios required changes in procedures, equipment configuration, and safety requirements. All jobs had to consider environmental criteria in addition to the operator's testing policies; therefore, different methods for achieving job goals were required. The lessons learned and presented will be applicable to today's scenarios and will be discussed to help determine proper testing procedures for current jobs. Well tests are conducted using many different downhole tools and procedures. An overview of these topics will include:Efficiency gains and operational advantagesNew technologies for more accurate well testing evaluationsCollection of downhole samples in PVT conditions to provide valuable data for future development. These new technologies are an excellent example of how technical advances in the oil industry (gauges, Downhole equipment, samplers, etc.) have been applied to operations in the oilfield to improve the decision-making capabilities of the oil and gas industry and increase well-testing evaluation success, even in extreme environments. These enhancements result in improved economic and operational efficiency as well as greater safety, both for the involved personnel and the environment. Introduction Traditionally, well testing has been used for many years as a reliable, dynamic method to retrieve a variety of information from the reservoir, including permeability, formation damage, bottomhole pressure and temperature, fluid samples, and production quantification. Over time, methods and equipment have evolved, expanding well-test capabilities to different scenarios and adapting to more demanding environmental and safety constraints. Nevertheless, in recent years, high-pressure and high-temperature (HPHT) drilled wells have become more common; thus, required techniques to meet industry challenges must be implemented. It is not necessary to mention that proper planning, people, and qualified equipment will be always the key factor a successful well test, especially considering that well and reservoir conditions could change from one region to another. In addition, previous documented experience in similar cases will be always well received because they can provide relevant information that will help us to make appropriate decisions. High-temperature (HT) wells are normally defined as having bottomhole temperatures in excess of 300°F, and extreme HT wells are defined as having bottomhole temperatures between 350°F and 400°F.