Method for controlling fluid interface level in gravity drainage oil recovery processes with crossflow
In a method for controlling interface level between a liquid inventory and an overlying steam chamber in a subterranean petroleum-bearing formation, an inflow relationship is developed to predict the vertical position in a gravity field of the interface between the two fluids (liquid and steam) with a density contrast relative to a horizontal producer well. The inflow relationship is applied to producer well completions by designing the completion to raise or lower sand face pressures according to mobility variations over the horizontal length of the well. This pressure distribution will affect liquid levels according to the inflow relationship. The completion can include tubing-conveyed or liner-conveyed flow control devices to create flow network that provides a customized sand face pressure distribution. Axial flow relationships between adjacent locations along the producer well may be modeled in order to develop an axial flow network to facilitate estimation of liquid levels at selected locations.
1. A method for characterizing an axial flow relationship relating the conditions at two axial locations along a horizontal producer well disposed within a petroleum-bearing formation to the axial flow rate through a liquid inventory surrounding the producer well, comprising the steps of:
(a) characterizing the gravity inflow performance relationship (IPR) at two axial locations along the producer well;
(b) evaluating the axial hydraulic conductivity of the liquid inventory at both locations;
(c) interpolating to approximate the axial hydraulic conductivity of the liquid inventory between the two locations; and
(d) calculating the axial flow rate through the liquid inventory as the product of the axial hydraulic conductivity, effective axial hydraulic gradient, and mean flow area.
2. A method as in claim 1 wherein the axial hydraulic conductivity of the liquid inventory between the two locations is taken as the average of the axial hydraulic conductivity at the first location and the axial hydraulic conductivity at the second location.
3. A method as in claim 1 wherein when conditions other than the liquid level are approximately equal at the two locations, the axial hydraulic conductivity of the liquid inventory at the first location is assumed to equal the axial hydraulic conductivity at the second location and, in turn, the axial hydraulic conductivity between the two locations.
4. A method as in claim 1 wherein the effective axial hydraulic gradient between the two locations is taken as the difference between the liquid level at the first location and the liquid level at the second location, divided by the axial distance between the two locations.
5. A method as in claim 1 wherein the gravity IPR is characterized at plurality of axial locations along the producer well, and an axial flow relationship is characterized for each pair of adjacent locations to create a system of axial flow relationships.