Field scale in-situ combustion ISC modelling of a heavy oil field of Western Onshore, India

Field scale in-situ combustion ISC modelling of a heavy oil field of Western Onshore, India

Crude oil

Viscosity

Temperature

Recovery

Thermal oil recovery

In situ combustion

Kinetic parameters

Heavy oil production

Oil fields

Petroleum reservoirs

Aquifers

Kinetic theory

Thermooxidation

Indium compounds

Field-scale reservoir simulation of In-Situ Combustion (ISC) process has been a grey area worldwide, due to the complexities of reactions involved and availability of kinetic model that can cover every aspects of an ISC process properly i.e. Pyrolysis/Cracking, Low Temperature Oxidation (LTO) & High temperature oxidation (HTO) reactions. The present paper is an endeavour to model ISC, using an Kinetic Model containing 6 reactions in one of the Heavy oil field located in Western Onshore, India. Selection of Pseudo-components plays a pivotal role in modelling of ISC simulation and should represent the burning characteristics/Oxidation behaviour of oil along with the chemical & physical changes it undergoes during different phases of a combustion process. As such a kinetic model comprising of 2 pseudocomponents Maltenes & Asphaltenes, was used for ISC simulation in Thermal simulator considering the above requirements & computational run time. To validate the kinetic model, Combustion-tube experiment and Pilot area performance were history matched. Finally, the results and understanding acquired were used for full field ISC simulation. The ISC process as a thermal recovery technique has been instrumental in enhancing the oil recovery from the field. The viscosity of the crude changes from ~ 150 cP to 400 cP as we move from south to north. The field is supported by an active edge water aquifer from the east. The ISC pilot was implemented in southern part of the field in 1990, followed by semi-commercialization in 1992, and full field implementation in 1997 onwards. The efficacy of the process can be judged from the fact that the recoveries from the southernmost part of the field stands around ~55% of STOIIP. A field scale simulation was performed in the remaining area where the recoveries are around ~30-35 % and there is still scope of improvement. Dynamic model incorporating areal viscosity variation & improved kinetic model was used for ISC simulation. After achieving satisfactory History match, a revised scheme was formulated with an objective to improve overall recovery from target area. The scheme comprises of 7 additional oil producers & 4 additional air injectors for better air distribution & shifting of present injector row. The envisaged gain over base scenario is ~ 4 % additional recovery from the target area. The methodology outlined in this paper is able to capture the complexities of ISC process and offers a reliable approach for field scale simulation. Additionally, it also aids in improving insights of the process by deconstructing the hitherto esoteric underlying mechanisms of arguably the most challenging EOR process and enable us to better design the process. The understanding based on above simulation has been helpful in improving the performance of the ongoing ISC process. Copyright 2019, Society of Petroleum Engineers.

SPE Oil and Gas India Conference and Exhibition 2019, OGIC 2019, April 9, 2019 - April 11, 2019

2019

Meena, Rakesh Kumar

Singh, Ravi Shekhar

Upadhyay, Sandeep Kumar

Mitra, Sujit

conferencePaper

10.2118/194615-ms