Experimental Investigation on Microscopic Residual Oil Distribution During CO 2 Huff-and-Puff Process in Tight Oil Reservoirs

Kun Qian, Shenglai Yang, Hongen Dou, Qian Wang, Lu Wang and Yu Huang
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Kun Qian: State Key Lab of Oil and Gas Resources and Engineering, China University of Petroleum, Beijing 102249, China
Shenglai Yang: State Key Lab of Oil and Gas Resources and Engineering, China University of Petroleum, Beijing 102249, China
Hongen Dou: Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China
Qian Wang: State Key Lab of Oil and Gas Resources and Engineering, China University of Petroleum, Beijing 102249, China
Lu Wang: State Key Lab of Oil and Gas Resources and Engineering, China University of Petroleum, Beijing 102249, China
Yu Huang: State Key Lab of Oil and Gas Resources and Engineering, China University of Petroleum, Beijing 102249, China

Energies, 2018, vol. 11, issue 10, 1-16

Abstract: The determination of microscopic residual oil distribution is beneficial for exploiting reservoirs to their maximum potential. In order to investigate microscopic residual oil during the carbon dioxide (CO 2 ) huff-and-puff process in tight oil reservoirs, several CO 2 huff-and-puff tests with tight sandstone cores were conducted at various conditions. Then, nuclear magnetic resonance (NMR) was used to determine the microscopic residual oil distribution of the cores. The experiments showed that the oil recovery factor increased from 27.22% to 52.56% when injection pressure increased from 5 MPa to 13 MPa. The oil recovery was unable to be substantially enhanced as the injection pressure further increased beyond the minimum miscible pressure. The lower limit of pore distribution where the oil was recoverable corresponded to relaxation times of 2.68 ms, 1.29 ms, and 0.74 ms at an injection pressure of 5 MPa, 11 MPa, and 16 MPa, respectively. Longer soaking time also increased the lower limit of the oil-recoverable pore distribution. However, more cycles had no obvious effect on expanding the interval of oil-recoverable pore distribution. Therefore, higher injection pressure and longer soaking time convert the residual oil in smaller and blind pores into recoverable oil. This investigation provides some technical ideas for oilfields in design development programs for optimizing the production parameters during the CO 2 huff-and-puff process.

Keywords: tight oil reservoir; enhanced oil recovery; phase behavior; nuclear magnetic resonance; microscopic residual oil distribution (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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