Performance of 15 Years of Hydraulic Fracturing of Oil Wells in South of Oman

Abstract

The first application of Hydraulic Fracturing in the South Oman started in 2000 to enhance water disposal wells. In 2004 the first oil wells were frac'ed. Although the technology was deployed many times, it never grew into a conventional practice. From 2004 to 2017 on average 5 Oil Wells were hydraulically fractured on yearly basis. In November 2017, a Hydraulic Fracturing Maturation & Expansion Workshop was conducted with the vision of growing the application by applying new frac concepts. A focused effort was initiated to drastically reduce cost, and simultaneously increase the scope by executing larger frac campaigns. The first hydraulic fracturing campaign introducing the frac new concepts, started end 2018 and a rapid growth from 5 wells per year to 45 wells per year was anticipated in the next three years. This large growth of scope relied on a steady supply of frac candidates and needed to be supported by screening and selecting processes that are fit for purpose in finding candidates. Although more than a hundred wells had already been frac'ed wells, selection of the most appropriate wells for stimulation was and remains one of the greatest challenges. A frac performance database was created for over 100 wells that had been hydraulically fracture stimulated to date. Recognizing that the frac performance depends on many variables ranging from subsurface properties to surface execution of the frac job, the size of the dataset proved to be too small to find correlations using sophisticated multivariable regression methods. Instead, the dataset was analyzed through careful investigation and evaluation of each frac job. In this paper the net oil gain will be used as the key success criteria i.e., value driver to demonstrates how effective the frac is achieving its business objective. Some 40% of the producers had been producing from the same zone before the hydraulic fracture stimulation. This provided the opportunity to understand the efficiency of the stimulation in terms of the "stimulation ratio" i.e., measuring the net oil gain. This paper will focus on investigating the suitability of frac'ing the reservoir based on the initial production variables; Gross Rate and BS&W. Also, this paper will discuss benefits and impacts of Hoist versus Coiled-Tubing clean-out on the frac delivery process and compare the frac performance. To date, the project demonstrated that hydraulic fracturing at low cost, can be applied as a viable development concept for producing oil wells, with the potential unlock additional and new reserves. Significant folds in production increase are possible from 2x to 7x.