Blasingame Typecurve Analysis

Boundary-Dominated Match

Transient Match

Blasingame represents the first of the modern typecurve methods (SPE 028688, 1994). It features pressure normalized rates, and introduces the concept of material balance time (i.e. boundary-dominated superposition time) to generate fully analytical constant rate typecurves featuring a single depletion stem, regardless of the reservoir structure (shape and size) or drive mechanism. Blasingame analysis results include skin factor, formation permeability, in-place fluid volumes, and reservoir drainage area. The flow rate integral and flow rate integral derivative functions allow for more accurate decline typecurve matches than would be possible using flow-rate data alone. These integral functions also eliminate problems associated with the analysis of field production data with erratic production rate and bottomhole pressure behaviour. Blasingame analysis is particularly useful in the modeling of suspected elliptical drainage patterns and open-hole horizontal wells, which have transitioned into boundary-dominated flow.

Note:   For information on the Blasingame typecurve theory and equations, see Blasingame Typecurve Analysis Theory.

The Blasingame typecurve analysis method uses the following models:

Boundary-Dominated Match

To obtain information about reserves and drainage area, we recommend that you focus on the boundary-dominated (depletion) stems of the typecurves. These are located on the right-side of the plot, where each set of typecurves converges to a single line. The Blasingame typecurve analysis does not require hyperbolic exponent values. Instead, the data is matched on the single depletion stem. As the data is moved about the plot, the OGIP / OOIP is continuously updated on the Analysis tab. 

For gas reservoirs whose fluid properties are strongly a function of pressure, the data points appear to "stretch" and "contract", as they are moved around the screen. This is because of the pseudo-time effect. Harmony recalculates gas properties at average reservoir pressures based on the calculated OGIP from the typecurve match. As the match is modified, OGIP, average reservoir pressure, and material balance pseudo-time are automatically recalculated, and the data points are repositioned accordingly.

Transient Match

To obtain information about permeability and skin, you should focus on the transient stems of the typecurves. On the Blasingame typecurve plot, these appear on the left-side of the plot as a “fan” of different reD values for the radial and water-drive models, re / xf values for the fracture and finite conductivity fracture models, b/xf values for the elliptical flow model, and LD for the horizontal model. You can select the best matching typecurve, which provides an associated reD (or re / xf, b / xf, LD) value.

From the selection, Harmony calculates: