In the last decades, the major oil companies have moved aggressively toward challenging targets such as deep and ultra-deep water environments to increase their hydrocarbon reserves portfolio. To deal with these new targets, attractive but located in harsh environments, technology has to improve significantly as well as the attention to be paid to operate under safe conditions. Operational daily costs are generally huge, sometime in excess of 1 million US$. As a consequence, the goal is to achieve a satisfactory balance between the value of information about the reservoir to be investigated and the ability to operate in a cost-effective manner. The option of capturing real time downhole P&T data by using electric cables when testing an exploration well is considered less and less attractive due to intrinsic safety risks. This has triggered significant developments in the wireless technology in recent years. Real time data are transmitted acoustically, removing the need for wireline operations. This wireless technology proved to be very effective increasing the test efficiency, optimizing the test sequence to acquire the well/reservoir response, minimizing costs and operating in a totally safe way. A real field application on an offshore exploration gas well is presented in this paper. The test offered the opportunity to assess both benefits and limitations of the technology.

In a global context aiming to unlock a low carbon future by industry decarbonization, developing the infrastructure for capturing and storing CO2 emissions is a key target of countries, energy companies and regulatory bodies. Injection for geological storage in suitable reservoirs is an advantageous option which presents challenges related to the completion accessories and string exposed to the injected fluid and the thermodynamical loads during injection and the well life. The purpose of this work is to simulate by numerical analysis and full-scale test, the behavior of a gas-tight Metal-to-Metal OCTG premium dope-free connection when subjected to low temperatures and loads generated by the effect of a sudden CO2 high pressure drop during injection in depleted reservoirs. Extreme temperature drop down caused by the Joule-Thompson (J-T) effect between injection conditions (P-T) inside the tubular and those in the annulus, may expose tubing connections to a thermal shock reaching a temperature near the theoretical figure of -78.5°C. This temperature drop assumed as worst-case scenario is also explored. The analysis is performed considering estimated loads for a CO2 injection case study. The numerical analysis and full-scale test performed confirm the structural and sealability performance of the connection is not affected by the exposure to such low temperatures. Additionally, transient thermal loads, with a drop of approximately 100°C, appears to be not critical for the metal-to-metal dope-free seal integrity and also not affecting the structural integrity of the connection. The challenges setting up of a prototype testing frame, simulating the cooling by thermal shock, lead to a methodology for assessing CCS projects premium connection able to define a robust testing protocol for cryogenic temperatures. The numerical and full-scale results collected on the tested connection size, together with the ones previously tested, allow extrapolation to near sizes of the same premium thread family. The results achieved by testing a premium connection which has been subjected to a thermal shock approaching -78.5°C represent a forefront in the industry, demonstrating the reliability of the product not only in operative conditions during CO2 injection, but also after an extreme event, assessing performance for the CCUS storage projects.

In the need for world decarbonization, the idea of utilizing available, suitable and/or depleted oil and gas reservoirs to inject CO2 has become a new objective for energy companies, this is the so-called Carbon Capture and Storage (CCS) application. Though injecting CO2 is not new for the industry as Enhanced Oil Recovery (EOR) has been thoroughly used around the globe, the particularities of injecting CO2 at a greater scale impose new challenges from the metallurgical and mechanical perspectives. During the injection of CO2, the string will be subjected to loads and pressures that will be generally low when compared to the performance of the pipes and modern gas-tight Metal-to-Metal seal OCTG premium connections. The main concern of this application is typically associated with the CO2 behavior and the thermodynamic loads produced during the injection. In a steady state condition and depending on the reservoir pressure, temperatures could drop as low as -20/-35°C. In a less probable scenario of a sudden exposure of the CO2 in the well to the atmospheric pressure, the expansion could produce a further reduction in temperature due to Joule-Thomson (J-T) effect reaching a theoretical limit of approximately -78°C. The purpose of this experimental activity is to evaluate by means of numerical analysis and physical full-scale test, the behavior of a gas-tight dope-free premium connection when subjected to low temperatures and loads generated by CO2 expansion during injection in depleted reservoirs. In particular, the extreme reduction in temperature in case of an uncontrolled release into the atmosphere is investigated. For this purpose, a connection is exposed to a temperature of around -78°C, and both its structural and sealing responses are verified. The analysis is performed considering estimated loads for a CO2 injection case study. The results of the evaluations demonstrate that neither the structural capacity nor the sealing response are affected by the sudden temperature drop. Additionally, these results are also confirmed by the numerical evaluations. In the simulation, well loads affected by the additional tensile stresses produced by the contraction of the constrained string remain well inside the connection service envelope. The combination of these two tools defines a state-of-the-art methodology for assessing premium connection under cryogenic temperatures in CCS projects. The results achieved by the premium connection subjected to a thermal shock of nearly -78°C represent a forefront in the industry. The experiment, demonstrated that the product maintains its full reliability in operative conditions after being subjected to an extreme event related to the application risks, confirming its adequate performance in CO2 injection and storage projects.