During pseudo steady state flow, the slope of the pressure change is 1 during which type of well test?

• A. Build-Up
• B. Drawdown
• C. Shut-In
• D. Final Test

Answer: (B)

In a constant-rate drawdown test, the flow around the well reaches a pseudo steady state where the reservoir pressure near the well declines at a steady, roughly linear rate with time. Because you’re pumping at a fixed rate, the pressure drop accumulates uniformly, so the pressure history p(t) shows a straight-line change over time. That linear, steady decline corresponds to the slope being unity in the standard representations used for pseudo steady state analysis. In buildup, shut-in, or final-test scenarios, the boundary conditions create different pressure responses (pressure rising after shutdown, or more complex transient behavior), so they don’t exhibit that same linear, constant-slope behavior.