How To Apply the Flow Velocity as a Design Criterion in RPM Treatments

Abstract

Summary The effect of water control using relative permeability modification (RPM) depends strongly on the well's flow rate because the permeability reduction decreases as the flow velocity increases. This will affect the volume and the properties of the injected RPM fluid. This paper discusses how the velocity-dependent permeability reduction can be accounted for in the job design. The approach is to introduce a velocity-dependent permeability reduction and to solve the Darcy law for non-Newtonian flow. Coreflood experiments report permeability reduction as residual resistance factors (RRFw and RRFo). In scaling up to field situations, the reduction in productivity is a better measure. Designing an RPM treatment to a fixed reduction in water productivity demonstrated that low-volume, high permeability reduction is better than larger volumes with lower permeability reduction. In highly productive wells, there may be situations where certain RPM systems fail to reduce the water productivity adequately. By including pressure constraints on the injection of the RPM fluid, the planned pumping schedule is derived. The criteria for increased oil production are reported as a balance between (1) increased drawdown based on the water-cut reduction and improved lift and (2) reduction in oil productivity. The critical oil productivity depends on the water productivity, initial water cut, density difference between the water and the hydrocarbon phases, and true vertical depth (TVD). It is clearly demonstrated that the potential for increased oil production increases by increasing the ratio between the oil- and the water-productivity reduction (M). In addition, M increases as RRFw increases and the treatment volume decreases. The time to restore the productivity from the oil zone, the cleanup time, can be understood through the fractional-flow theory. In theory, the cleanup time can be derived from relative permeability curves or the saturation profiles during the oil back production. Also, the cleanup time was reduced by the use of low-volume, high water-permeability reduction.

New Insights into the Mechanism of Mobility Reduction by Associative Type Copolymers

“…14. These results are in agreements with previous work (Stavland 2010) reporting that water based polymers will selectively reduce the water permeability and not the oil permeability. …”

A Multiscale Investigation of Cross-Linked Polymer Gel Injection in Sandstone Gas Reservoirs: Implications for Water Shutoff Treatment

“…However, the efficiency of cross-linked polymers (gels) was found to vary with gas, oil, and water flow rates. − In addition, the relative permeability modifier (RPM) performance decreases as the fluid flow rate increases, posing a risk of overestimating the water-cut reduction potential. Therefore, the influence of fluid flow rate needs to be included in the RPM design …”

“…Therefore, the influence of fluid flow rate needs to be included in the RPM design. 27 Furthermore, it was previously shown that the efficiency of a water shutoff treatment strongly depends on the gel quality (i.e., the gel's rigidity and stability). 28−31 Moreover, while there have been recent insights into the mechanism of gel deformation and the associated disproportionate permeability reduction (DPR), 25,32−35 further scientific understanding of gel behavior in relation to injection rates is required to guarantee successful gel placement in gas wells.…”

Disproportionate Permeability Reduction of Water-Soluble Silicate Gelants - Importance of Formation Wettability

“…Many researchers use the term relative permeability modification (RPM) interchangeably, and relative permeability modifier for the treatment fluid. Sydansk and Seright (2007) have presented an extensive overview of the history and applications of DPR/RPM treatments in petroleum reservoirs, and Liang et al (1995), Stavland and Nilsson (2001), Stavland (2010), and Sydansk and Romero-Zerón (2011) discussed the DPR mechanisms.…”