Analysis of Pressure-Buildup Data From a Well in a Multiwell System

Abstract

Summary This work investigates the buildup response of a well located in a system of producing wells completed in a closed, bounded reservoir. Using an analysis method based on the pressure derivative, we show that the drainage area of the well (at the instant of shut-in) and the flow-capacity (permeability-thickness) product can be computed directly from the derivative of pressure-buildup data even in cases where conventional semilog straight lines are not well defined. The analysis methods assume that the buildup-surveyed well has established its own drainage area before shut-in. For a system of wells located in a closed, bounded reservoir, this means that pseudo-steady-state flow prevails at the instant of shut-in. We also present a second method for estimating a well's drainage area from pressure-buildup data. The second method relies on the fact that during buildup, the well's shut-in pressure increases to a maximum and then decreases as a result of interference from neighboring producing wells. It is shown that the maximum shut-in pressure, and the time at which it occurs, often can also be used to compute the well's drainage area at the instant of shut-in and the average pressure in this drainage area.