Characterization of operative mechanisms in gravity drainage field projects through dimensional analysis

Document Type

Conference Proceeding

Publication Date

1-1-2006

Abstract

The Gas-Assisted Gravity Drainage (GAGD) process is being developed through a joint effort between the U.S. DOE and LSU, to examine the effectiveness of improving gravity drainage of oil to horizontal producers by injecting gas through existing vertical wells. To facilitate fair and effective performance comparisons between the conventional water-alternating-gas (WAG) and the GAGD process, and decipher the controlling operational multiphase mechanisms in gas injection EOR processes, the dimensional analysis approach was employed. Nine gravity stable and eight WAG field applications in the U.S., Canada, and rest of the World were studied for this purpose. A newly defined 'index of productivity' and five dimensionless groups, namely Capillary (NC), Bond (NB), Dombrowski-Brownell (NOB), Gravity (N G), and Grattoni et al.'s 'N' group were calculated for these gravity stable field projects. Dimensional analysis results for all gravity drainage field projects indicated that these dimensionless numbers can be classified into two groups: (i) petrophysical parameter(s) dependent groups: NB, NDB and N, and (ii) operational parameter(s) dependent groups: NC and NG. NC and NB groups effectively envelope the interplay of the dominant reservoir forces, namely gravity, viscous, and capillary forces. These groups coupled with the microscopic Bond number (NDB) aid in characterizing the flow regimes and governing forces in the field as well as laboratory displacements. The NG and N groups provide useful augmentation for scale-up and displacement characterizations. This paper provides the results of step-by-step dimensional analyses for all the field cases studied and attempts to characterize the controlling multiphase mechanisms in gas injection EOR processes. Additionally, this work attempts to characterize the fluid dynamics associated with gravity drainage processes through existing (namely, capillary number, bond number, gravity number etc.) and newly defined ("gravity drainage" number) dimensionless groups. Copyright 2006, Society of Petroleum Engineers.

Publication Source (Journal or Book title)

Proceedings - SPE Annual Technical Conference and Exhibition

First Page

4512

Last Page

4530

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