Which flow regime describes bilinear flow due to finite conductivity vertical fracture?

Which flow regime describes bilinear flow due to finite conductivity vertical fracture?

• A. Wellbore Storage
• B. Infinite Acting Radial Flow
• C. Bilinear Flow
• D. Spherical Flow

Answer: (C)

Bilinear flow appears when a vertical fracture has finite conductivity. In this situation the pressure field around the fracture cannot be described by simple radial flow into the formation. Instead, the flow pattern becomes effectively two-dimensional in the fracture plane: fluid enters the fracture from the surrounding matrix and spreads along two principal directions within the fracture region. Because the pressure variation along these two directions can be approximated as linear, the overall pressure response can be described by a product of two linear profiles, giving a bilinear pressure distribution. This regime captures the influence of the fracture’s finite conductivity on the transient flow, sitting between the very early wellbore storage effects and the later radial flow behavior. Wellbore storage dominates at the earliest times when the fluid is primarily in the wellbore. Infinite acting radial flow describes a scenario without fracture-imposed limitations, where flow radiates outward in three dimensions. Spherical flow refers to a different geometric situation altogether, not the two-dimensional fracture-dominated flow around a vertical, finite-conductivity fracture.

Bilinear flow appears when a vertical fracture has finite conductivity. In this situation the pressure field around the fracture cannot be described by simple radial flow into the formation. Instead, the flow pattern becomes effectively two-dimensional in the fracture plane: fluid enters the fracture from the surrounding matrix and spreads along two principal directions within the fracture region. Because the pressure variation along these two directions can be approximated as linear, the overall pressure response can be described by a product of two linear profiles, giving a bilinear pressure distribution. This regime captures the influence of the fracture’s finite conductivity on the transient flow, sitting between the very early wellbore storage effects and the later radial flow behavior.

Wellbore storage dominates at the earliest times when the fluid is primarily in the wellbore. Infinite acting radial flow describes a scenario without fracture-imposed limitations, where flow radiates outward in three dimensions. Spherical flow refers to a different geometric situation altogether, not the two-dimensional fracture-dominated flow around a vertical, finite-conductivity fracture.