Study on Heat Self-generated Mixed-gas Assisted Steam Huff-n-Puff for Enhance Heavy Oil Recovery

Abstract

ABSTRACT In this paper, based on the in-situ generation technology and the advantage of non-condensate gas (N2 and CO2)-assisted steam huff-n-puff, a new technology of heat self-generated mixed-gas (HSGMG)-assisted steam huff-n-puff is proposed, which can further enhance heavy oil recovery by using different gas-assisted steam huff-n-puff. Based on the optimization of HSGMG agent solution, the reliability and relative error of the experimental results and calculated pressurization effect were evaluated, and its heavy oil viscosity reduction rate (HOVRR) was investigated. Results showed that the experiments were reliable, and its relative error was small. The calculated pressurization effect indicated that formation energy could be supplemented. Its HOVRR was very significant above 90°C. The oil displacement efficiency of this technology was further examined by sand-pack huff-n-puff test under different conditions. The results indicated that a higher total molar concentration, a larger slug size, and a faster pressure depletion rate contributed to improved oil displacement efficiency, but the economic indicator was reduced. When the total injection volume was constant, this efficiency of huff-n-puff with different injection patterns was little different. Abbreviation: DDTFW: diluted different times formation water; EHOR: enhanced heavy oil recovery; HOVRR: heavy oil viscosity reduction rate; HSGMG: heat self-generated mixed-gas; HTPR: high temperature and pressure reactor; IFP: initial formation pressure; IP: initial pressure; IOR: incremental oil recovery; L-P: lipid molar proportion; PDR: different pressure depletion rate; PST: pressure stabilization time; RT: reaction temperature; TIOR: total incremental oil recovery; TMC: total molar concentration.