GEOT 464 Disk used No. pages 24, DTD=4.3.1 Version 7.51e ARTICLE IN PRESS Application of modern well test analysis techniques to pressure transient tests in Kizildere geothermal field, Turkey Mustafa Onur a, *, Ayse Donmez Zeybek b , Umran Serpen a , Ihsan Murat Gok a a Department of Petroleum and Natural Gas Engineering, Faculty of Mines, Istanbul Technical University, Istanbul 80626, Turkey b Al-Mutlaq Compound, Villa No.10, PO Box 2139, Al-Khobar 31952, Saudi Arabia Received 21 February 2002; accepted 8 October 2002 Abstract The analyses of two build-up tests and one interference test in the Kizildere geothermal field, Turkey, are presented. Modern well test analysis methods based on pressure-derivative (logarithmic time rate of pressure) and non-linear regression, as well as conventional log–log and semi-log straight-line methods, have been used in the interpretation of these field pressure tests. Pressure transient models based on both homogeneous reservoirs and fractal reservoirs without matrix participation are considered in the analysis. It is shown that the use of con- ventional analysis methods alone can lead to an inaccurate interpretation of these field tests, and the use of modern analysis techniques in conjunction with conventional analysis techni- ques provides a more reliable and accurate interpretation of the well test data in the Kizildere geothermal field. The information obtained (e.g., estimates of permeability thickness and fractal dimensions) from analyses of these tests should prove useful for reservoir character- ization studies in the Kizildere field, where reinjection is scheduled to begin soon. Finally, the modern interpretation methods described in this paper are recommended for analysis of well test pressure data from geothermal reservoirs. # 2003 CNR. Published by Elsevier Science Ltd. All rights reserved. Keywords: Reservoir; Pressure transient testing; Pressure-derivative; Non-linear regression; Fractal; Kizildere; Turkey Geothermics 32 (2003) www.elsevier.com/locate/geothermics 0375-6505/02/$30.00 # 2003 CNR. Published by Elsevier Science Ltd. All rights reserved. doi:10.1016/S0375-6505(02)00068-8 * Corresponding author. Tel.: +90-212-285-6269; fax: +90-212-285-6263. E-mail address: onur@itu.edu.tr (M. Onur).