https://doi.org/10.3311/PPch.17236 462|Creative Commons Attribution b Periodica Polytechnica Chemical Engineering, 65(4), pp. 462–475, 2021 Recent Approaches, Catalysts and Formulations for Enhanced Recovery of Heavy Crude Oils Umar Gaya1,2* 1 Department of Pure and Industrial Chemistry, Faculty of Physical Sciences, Bayero University, 700241 Kano, 1 Gwarzo Road, Nigeria 2 Directorate of Science and Engineering Infrastructure, National Agency for Science and Engineering Infrastructure (NASENI), Idu Industrial Layout, 900104 Garki, Abuja, Nigeria * Corresponding author, e-mail:
[email protected] Received: 20 September 2020, Accepted: 04 December 2020, Published online: 16 August 2021 Abstract Crude oil deposits as light/heavy form all over the world. With the continued depletion of the conventional crude and reserves trending heavier, the interest to maximise heavy oil recovery continues to emerge in importance. Ordinarily, the traditional oil recovery stages leave behind a large amount of heavy oil trapped in porous reservoir structure, making the imperative of additional or enhanced oil recovery (EOR) technologies. Besides, the integration of downhole in-situ upgrading along with oil recovery techniques not only improves the efficiency of production but also the quality of the produced oil, avoiding several surface handling costs and processing challenges. In this review, we present an outline of chemical agents underpinning these enabling technologies with a focus on the current approaches, new formulations and future directions. Keywords in-situ upgrading, enhanced oil recovery, aquathermolysis, heavy oil, catalyst 1 Introduction The world is caught up in the ever-increasing need for Table 1 Selected definitions of heavy crude oil at 15 °C.