An Emperical Method To Correct Pulse-Test Results For Wellbore Storage At The Pulsing Well
Authors: Mondragon Julius J. , Menzie Donald E. 
Published: December 2007

In the analysis of pulse-test theory, it has been shown that wellbore storage in the response well will cause the time lag to increase and the maximum pressure amplitude to decrease. Also it has been shown pressure amplitude to decrease. Also it has been shown that wellbore storage at the pulsing well reduces the maximum pressure amplitude of the pulse and increases the time lag. The net result is that the transmissibility is kh/mu, is underestimated, and the storativity, beta h, is overestimated.

Although there is no general correlation to correct for wellbore storage at the pulsing well, wellbore storage in the response well can be eliminated by placing a bottomhole packer around the pressure bomb. pressure bomb. The object of this paper is to show how emperically developed equations can correct pulse-test results for the case with wellbore storage at the pulsing well. A group of correction equations were pulsing well. A group of correction equations were developed that would correct pulse-test results from an average 33% error to an average 3% error for values of transmissibility, and would correct the storativity from an average 14% error to an average 5% error.

Introduction

Two wells are used to conduct a pulse test. The two wells are termed the pulsing or active well and the responding or observation well. A series of flow disturbances is generated at the pulsing well and the pressure response is recorded at the responding well. pressure response is recorded at the responding well. Alternate periods of production and shut-in, or injection and shut-in are used to generate the flow disturbance. The pressure response is recorded using a highly sensitive differential pressure gauge.

It has been shown that wellbore storage at the observation well will cause a delay in the time lag at which the maximum pressure is observed and a reduction in the maximum observed pressure response.

Wellbore storage at the pulsing well can cause an underestimation of the transmissivity and an overestimation of the storativity when analyzing pulse-test data. pulse-test data.

REVIEW OF LITERATURE

Pulse Testing Pulse Testing Pulse testing was first introduced in 1966 by Johnson et al. Brigham developed some approximate equations that describe the theoretical rationale behind pulse testing. Vela and McKinley studied the effects of areal heterogeneities on pulse-test results. In 1970, Woods developed a pulse-test results. In 1970, Woods developed a mathematical model to study pulse-test results in a two-zone reservoir. In 1972, Odeh and McMillen presented a theoretical analysis of pulse presented a theoretical analysis of pulse propagation in linear cores saturated with air based on propagation in linear cores saturated with air based on solving the diffusivity equation for flow in porous media. In 1975, Prats and Scott showed the effects of wellbore storage at the response well on a pulse test. Jargon, in 1976, showed that wellbore storage at the pulsing well will cause an underestimation of transmissivity and an overestimation of storativity.

Wellbore Storage

The effect of wellbore storage was considered originally by van Everdinger and Hurst in 1949. In 1955, Gladfelter et al. presented a method for correcting pressure buildup data for wellbore storage. In 1970, Agarwal et al. examined the wellbore storage and skin-effect problem end presented dimensionless pressure vs dimensionless presented dimensionless pressure vs dimensionless time plots for a well in an infinitely large reservoir, producing at constant surface production rate. An investigation of the effect of wellbore storage and skin effect on transient flow was conducted using a finite-difference solution to the basic partial differential equation by Wattenbarger et al. in 1970. Ramey and Agarwal concluded (in 1972) that annulus unloading and wellbore storage to be an important physical effect that often controls the behavior of early pressure data taken during a well test.