Title: Development and evaluation of fracture gradient curve model: a case study of south-central Kazakhstan

Authors: Branimir Stanisavljevic; Vesna Karovic Maricic; Irena Isakov

Addresses: Faculty for Mining and Geology, University of Belgrade, Belgrade, Serbia; Drilling and Workover Engineer, PM Lucas, Ostroska 8, Kac – Novi Sad, Serbia ' Department of Petroleum Engineering, Faculty of Mining and Geology, University of Belgrade, Belgrade, Serbia ' Faculty for Mining and Geology, University of Belgrade, Belgrade, Serbia; NTC NIS-Naftagas, Narodnog Fronta 8, Novi Sad, Serbia

Abstract: An accurate fracture gradient value is one of the most important issues in oil and gas well design and drilling. The value of a fracture gradient is a critical parameter for determining the drilling mud weight and selecting the proper depths for setting the casing in the planning process of drilling operations. This paper proposed the new curve model of fracture gradient for the south-central Kazakhstan (central Asia) region based on the analysis of leak-off test and format integrity test results. Data from more than 400 tested wells were analysed and compared with the results of existing methods for predicting the fracture gradient and with the results from previous drilling projects in that region. By using the new curve model, the more precise values of fracture gradient are determined. Besides an improved fracture gradient model development and validation, the model's analytical expressions are presented. The article's most important results are determining the model's values of fracture gradient and providing a more accurate calculation of mud weight, less mud losses, more precise evaluations of cementing operations, better selection of the casing setting depth and improved drilling safety. [Received: February 13, 2022; Accepted: June 2, 2022]

Keywords: fracture gradient; new curve model; oil well design; drilling; Kazakhstan.

DOI: 10.1504/IJOGCT.2023.128042

International Journal of Oil, Gas and Coal Technology, 2023 Vol.32 No.2, pp.126 - 140

Received: 11 Feb 2022
Accepted: 02 Jun 2022
Published online: 04 Jan 2023 *

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