Over the last few years, ADNOC has systematically investigated a new polymer-based EOR scheme to improve sweep efficiency in high temperature and high salinity (HTHS) carbonate reservoirs in Abu Dhabi (Masalmeh et al., 2014). Consequently, ADNOC has developed a thorough de-risking program for the new EOR concept in these carbonate reservoirs. The de-risking program includes extensive laboratory experimental studies and field injectivity tests to ensure that the selected polymer can be propagated in the target reservoirs. A new polymer with high 2-acrylamido-tertiary-butyl sulfonic acid (ATBS) content was identified, based on extensive laboratory studies (Masalmeh, et al., 2019, Dupuis, et al., 2017, Jouenne 2020), and an initial polymer injectivity test (PIT) was conducted in 2019 at 250°F and salinity >200,000 ppm, with low H2S content (Rachapudi, et al., 2020, Leon and Masalmeh, 2021). The next step for ADNOC was to extend polymer application to harsher field conditions, including higher H2S content. Accordingly, a PIT was designed in preparation for a multi-well pilot This paper presents ADNOC's follow-up PIT, which expands the envelope of polymer flooding to dissolve H2S concentrations of 20 - 40 ppm to confirm injectivity at representative field conditions and in situ polymer performance. The PIT was executed over five months, from February 2021 to July 2021, followed by a chase water flood that will run until December 2021. A total of 108,392 barrels of polymer solution were successfully injected during the PIT. The extensive dataset acquired was used to assess injectivity and in-depth mobility reduction associated with the new polymer. Preliminary results from the PIT suggest that all key performance indicators have been achieved, with a predictable viscosity yield and good injectivity at target rates, consistent with the laboratory data. The use of a down-hole shut-in tool (DHSIT) to acquire pressure fall-off (PFO) data clarified the near-wellbore behaviour of the polymer and allowed optimisation of the PIT programme. This paper assesses the importance of water quality on polymer solution preparation and injection performance and reviews operational data acquired during the testing period. Polymer properties determined during the PIT will be used to optimise field and sector models and will facilitate the evaluation of polymer EOR in other giant, heterogeneous carbonate reservoirs, leading to improved recovery in ADNOC and Middle East reservoirs.

Recent appraisal drilling undertaken by ADNOC in offshore Abu Dhabi has focussed on evaluation of the Middle Jurassic to Permian Deep Gas reservoir sequences. These formations are characterised by low porosity and permeability and typically contain either dry gas or gas condensate fluids. These appraisal activities form part of a larger program leading to development of these resources. Principal uncertainties addressed by appraisal drilling include determining fluid characteristics, reservoir properties and ultimately well deliverability. This paper uses one such recently drilled (typical) appraisal well as an example of the workflow employed. Exploration drilling of the Middle Jurassic to Permian reservoirs in this field dates back to 1984 and utilised available logging tools and techniques of the time. The current appraisal drilling program built on the results of this work and utilizes the latest available technology and interpretation techniques to both quantify reservoir and fluid properties and minimise subsurface development uncertainties. Typical data acquisition programs includes: conventional coring, advanced mud log data acquisition, triple-combo wireline data, borehole image data, elemental spectroscopy, azimuthal dipole sonic data and formation pressure measurements/samples. The formation evaluation program involved careful analysis and integration of this data to decide at first on formation sampling points and then subsequently testing zones. This approach necessitated the involvement of multiple stakeholders (end-users as well as people performing the interpretation) and required close communication to facilitate rapid, informed, decision making at key stages of the project execution. These different types of data become available at differing times during the course of drilling a well with the earlier acquired data informing the decision-making process on subsequent data acquisition. The first data to come in were the "mud logs" which includes drilling parameters (such as Rate of Penetration) and gas chromatography. This data provides an initial indication of potential zones of interest, along with fluid type. Following acquisition of wireline data, a "quicklook" formation evaluation was integrated with earlier geological analysis to determine the formation pressure and fluid sampling points. Combined together, these results formed the basis of an integrated reservoir and saturating fluid interpretation leading to the selection of perforation intervals for well testing. Effective implementation of this work flow requires a collaborative approach combined with ongoing data integration. This process of consultation across multiple subsurface disciplines and stepwise evaluation guiding future data acquisition requires a certain degree of evaluation flexibility but ultimately results in better decisions. The philosophy of integrating multiple data sources and disciplines in a collaborative evaluation and decision-making work flow is an essential enabler for the exploitation of the Deep Gas resource in Abu Dhabi. In the example well, test results are in accord with the log interpretation work and provide a path forward towards field development and gas production.