Well and Reservoir Parameters Estimation (K and Skin) Using the Statistical Diagnostic Approach….Part II

摘要

In pressure transient analysis, the derivative, typecurve and semi-log pressure curve is used to estimate wellbore and reservoir parameters. How accurate are this figures which solely depend on the extent of the transient period as interpreted by the derivative plot considered for reservoir characterization. Though this approach is universally accepted by welltest analysts, reservoir engineers and the academia in the oil and gas industry but the possibility of over or under estimating wellbore and reservoir parameter is not in doubt, hence there is need to checkmate such interpretation using alternative approach This paper focus on permeability and skin estimation using the statistical approach to checkmate the quantitative interpretation of the derivative method. Part 1 of this work focus on flow regime identification using the statistical method. Result from channel sand, low and high permeability reservoir, infinite acting and closed boundary indicates that the estimated permeability for both approach is much closed. Maximum difference of about 13% is notice in closed boundary model while the minimum difference is about 1% in infinite acting reservoir response. Generally, the best match for K and S estimate is seen in channel sand and high K, acidized model. Also in all cases considered, lower slope is obtained from the Statdev approach which is responsible for lower estimated permeability. Invariably the Statdev depict larger extent of transient flow regime as compare with the derivative, making it applicable even where data whose fingerprint for the transient period are insufficient for the analysis.