Determination Of Gas Well Stabilization Factors From Surface Flow Tests And Build-Up Tests
Authors: McMahon James J. 
Published: December 2007

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The stabilization factor can be defined as the ratio of a well's performance under psuedo-steady state conditions to the well's performance at the end of a given length of flowing time. For the purposes of using pressure build-up analyses in the Hugoton Field, it has been convenient to use the ratio of pressure build-up at the end of 72 hours compared to the maximum pressure build-up. In highly permeable reservoirs, the stabilization factor is approximately unity, but in the tighter, lower permeability reservoirs it can decrease to 0.25 or even lower values.

In general, stabilization can be considered an unsteady-state or transient flow phenomena. Therefore, it should be studied using the mathematical analyses developed for this type of flow. Most of the theoretical work has been completed by previous workers and the present study is mainly one of applying their work to field data, and very little new theory is introduced.

The data for this study is surface recorded information on a large number of wells in the Hugoton Fields of Kansas, Oklahoma and Texas. The results of analyzing surface pressure buildup information are compared with results of analyzing flow tests on the same wells, and from these analyses an attempt is made to predict the expected future performance of Hugoton Field gas wells.

The study concludes that the analyses of the pressure buildup data will accurately reflect the conditions necessary to predict stabilization factors for use in availability studies, that the analyses of flow data which is more difficult and expensive to obtain can often lead to erroneous conclusions, and a reasonable comparison between flow and build-up data can be realized if sufficient care is used in collecting and analyzing the basic data.

Introduction

Without an accurate knowledge of stabilization factors and other formation characteristics, future planning of operating facilities, future availabilities of gas, and future gas contracting requirements become difficult to anticipate.