Efficiency is a key factor on any operation. In this paper, we introduce the heterodyne Distributed Vibration Sensing (hDVS), which is an innovative technology based on fiber optic system to improve the duration of borehole seismic operations. We designed a survey aimed at comparing standard downhole geophone accelerometers measurements to i) optical fiber seismic installed inside the hybrid Wireline cable and ii) optical fiber clamped permanently to the well completion tubing. This comparison was conducted using a standard rig source VSP in association to advanced Offsets VSP. The purpose of the study was to evaluate this innovative technology and to assess the feasibility of drastic operation time reduction without compromising output data quality. To better evaluate the readiness of the technology, we decided to compare three distinct types of downhole measurements and designed a specific advanced acquisition which allowed us to compare various configurations. Consequently, the borehole seismic acquisition performed in the MR-SE1 well located in Makhrouga field (Tunisia) was split into two phases. Phase #1: during open-hole Wireline logging, using the standard downhole geophone accelerometers (VSI) and fiber optic seismic cable (single-mode cable) installed inside the Wireline logging cable (called hybrid Wireline cable). Phase #2: at the departure of the drilling rig, using a fiber optic seismic cable (single-mode cable) installed permanently along the intelligent completion. The results highlight the effectiveness of the hDVS technology with a proven decrease on operation timing, with reliable and good SNR recorded data. Nowadays, efficiency is a key requirement for any data acquisition process. The heterodyne Distributed Vibration Sensing (hDVS) is an innovative technology designed to achieve such effectiveness by making the Vertical Seismic Profile (VSP) a matter of minutes instead of hours, as using standard downhole equipment, without compromising output data reliability and allowing the measurements repeatability (no well interventions required). Finally, based on the quality of the dataset acquired, further analysis can be conducted for imaging purpose by analyzing the reflected waveforms, which could bring additional information and could change the way we are operating.

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The composite liner is made of a Glassfibre Reinforced Epoxy (GRE) resin, inserted in Carbon Steel tubing and it can be used in both production and water injection wells. Different laboratory tests performed either by manufacturers and by operators, have been carried out in order to confirm and verify the material characteristics and reliability. In particular, Eni in 2009 tested GRE in sour environment with CO2 and H2S to investigate the capability and service limits of the resin liner at different temperatures. According to the positive results of the tests, Eni has firstly applied GRE in 2005 in Tunisia where it was successful in reducing onshore workover costs and extending the life of Carbon Steel tubing in oil producer wells with high CO2 and water cut. The latest application was in Norway where it has been installed on water injector offshore wells, where, due to high corrosiveness of the injection fluid (raw seawater with antifouling chlorination), the liner was selected as cost effective alternative to high alloyed materials. More recently, Eni was involved in particularly challenging deepwater development projects with highly productive gas wells in sour and harsh environment. Typically, these applications require high grade Corrosion Resistant Alloys (CRA) production tubing with an important impact on the completion costs and operative run in hole issues. Following the positive experiences gained in the last 15 years in the application of glassfibre liner, it was evaluated the possibility to deploy the material as a corrosion barrier in well production tubings under more critical conditions. Eni decided to perform some additional laboratory tests in collaboration with Milan Polytechnic. Direct impact test and straight pipe test were performed in order to characterize the erosion behaviour of GRE composite material, supplied by two different manufacturers, and simulating the case of wells with high erosion rate risk. The results demonstrated GRE to have a good resistance to the solid particles erosion in comparison to very similar tests on Inconel Nickel Alloy material and confirmed the potential use of GRE as a corrosion resistance material when combined with Carbon Steel tubulars as an alternative to the usual high CRA materials in producer wells. This paper will present the characteristics of the technology, the laboratory tests performed with their results and the acceptable range of field conditions. Additionally, the paper will provide Eni field experiences, including feedback, lessons learned and economic evaluations.

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.