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CHAPTER FOURTEEN




              Other enhanced oil recovery
              methods




              Abstract

                 This chapter briefly presents other enhanced oil recovery (EOR) efforts. The efforts
                 include using sequential method of huff-n-puff gas injection and spontaneous imbibi-
                 tion, chemical blends, air foam drive, branched fractures, zipper fracture, refracturing,
                 diversion technology in fracturing, energized fluids, thermal recovery, and microbial
                 EOR.


              Keywords: Air foam; Microbial EOR; Branched fractures; Chemical blend; Diversion
              technology; Energized fluids; Refracturing; Thermal recovery; Zipper fracture.



                   14.1 Introduction
                   In addition to the enhanced oil recovery (EOR) methods described in
              the preceding chapters, additional efforts were made to enhance oil recovery
              from shale and tight reservoirs. This chapter briefly presents those efforts.
              The efforts include using sequential method of huff-n-puff gas injection
              and spontaneous imbibition, chemical blends, air foam drive, branched
              fractures, zipper fracture, refracturing, diversion technology in fracturing,
              energized fluids, thermal recovery, and microbial EOR.


                   14.2 Sequential method of huff-n-puff CO 2 injection
                   and surfactant-assisted spontaneous imbibition
                   As we have seen in earlier chapters, huff-n-puff gas injection can
              improve oil recovery, but the oil production rate will decline with injection
              cycle; at later cycles, the process may lose economic advantages. During this
              late time, water may be injected to activate spontaneous imbibition with
              surfactants added in the water which is called surfactant-assisted spontaneous
              imbibition (SASI). Zhang et al. (2018) first conducted huff-n-puff CO 2
              injection followed by SASI using sidewall cores. Fig. 14.1 shows the recov-
              ery factors (RF) from huff-n-puff CO 2 injection and surfactant-assisted


              Enhanced Oil Recovery in Shale and Tight Reservoirs  © 2020 James Sheng.
              ISBN: 978-0-12-815905-7                  Published by Elsevier Inc.
              https://doi.org/10.1016/B978-0-12-815905-7.00014-1  All rights reserved.  457 j
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