Effect of reservoir heterogeneity on improved shale oil recovery by CO 2 huff-n-puff

Cheng Chen, Matthew Balhoff, Kishore K. Mohanty

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

60 Scopus citations

Abstract

An equation-of-state based compositional reservoir simulator, UT-COMP, is used to simulate the improved oil recovery by CO2 huff-n-puff in a shale matrix typical of the Bakken Formation. Non-aqueous components are carefully lumped into seven pseudo components. Permeability fields with various heterogeneity and correlation lengths are generated. UT-COMP is able to solve the compositional model, despite the permeability difference between the fracture and matrix being six orders of magnitude. Multiple cycles of CO 2 huff-n-puff are simulated and compared with production by primary depressurization. The oil is first contact miscible with the injected CO 2 under the reservoir pressure. Simulations show that primary recovery outperforms CO2 huff-n-puff in an ideally homogenous reservoir because injected CO2 moves deep into the reservoir without much increase in near-well pressure, while CO2 huff-n-puff outperforms primary recovery if there exists a low-permeability region which keeps CO2 in the near-well bore injection region. In the latter case, the final recovery using CO2 huff-n-puff is higher than that from primary depressurization; the recovery in a single cycle is about 3.3%, which increases to 3.5% in about 3 cycles. The recovery factor after 1000 days by primary depressurization with production pressure of 1000 psi is 11.6%, which is in agreement with existing studies. The recovery increase can be fit by a two-parameter exponential function and the rate coefficient is found to be insensitive to correlation length, while depends mainly on reservoir heterogeneity. A linear relationship between heterogeneity and rate coefficient is obtained. This work is the first to investigate the effect of heterogeneity on improved hydrocarbon recovery by CO2 huff-n-puff, and will be valuable in understanding the coupling between shale properties and oil recovery.

Original languageEnglish
Title of host publicationSociety of Petroleum Engineers - SPE USA Unconventional Resources Conference 2013
Pages410-425
Number of pages16
StatePublished - 2013
EventSPE USA Unconventional Resources Conference 2013 - The Woodlands, TX, United States
Duration: 10 Apr 201212 Apr 2012

Publication series

NameSociety of Petroleum Engineers - SPE USA Unconventional Resources Conference 2013

Conference

ConferenceSPE USA Unconventional Resources Conference 2013
Country/TerritoryUnited States
CityThe Woodlands, TX
Period10/04/1212/04/12

Fingerprint

Dive into the research topics of 'Effect of reservoir heterogeneity on improved shale oil recovery by CO 2 huff-n-puff'. Together they form a unique fingerprint.

Cite this