Improving Economics of Hard-to-Recover Reserves Development. Case Study of Achimov Formation at Prirazlomnoe Oil Field.
Authors: Serdyuk Alexander , Valeev Sergey , Frolenkov Andrey , Lushnikov Alexey , Overin Alexander , Yudin Alexey , Kuznetsov Alexander , Gorlushko Anna 
Published: October 2018

The Achimov formation in Western Siberia has considerable potential for oil production, but development of these hard-to-recover reserves often is not profitable. This paper focuses on successful experience of the Achimov development in the Prirazlomnoye field in Western Siberia, where a new technology of hydraulic fracturing was applied, which allowed us not only to increase the oil inflows, but also to significantly reduce costs of hydraulic fracturing.

The main geological properties of the Achimov formation of the Prirazlomnoye field are high heterogeneity, high gross thickness (exceeding 100 m in some cases), and water-saturated layers in the bottom section. Under these conditions, the hydraulic fracturing design should provide effective inclusion of all sublayers; therefore, a significant amount of fracture materials is required. In addition, there should be a mechanism to prevent proppant settlement in the lower part of the fracture. Channel fracturing treatment made it possible to achieve significant progress in solving the problems of reservoir development in the Achimov. Due to the features of the technology, the required amount of proppant and fluid was minimized, thus reducing the cost of hydraulic fracturing. High concentrations of fiber material in the hydraulic fracturing fluid fixed the proppant in the upper part of the fracture, significantly reducing the water-cut of well products.

The paper describes the details of the development of the Achimov on the Prirazlomnoye field using hydraulic fracturing. Statistical results show the optimal parameters of the hydraulic fracture. A comparative analysis of hydraulic fracturing using the standard and channel technologies was made. The well completion and production data from several pads were used, and a comparison was made of 47 wells that had channel technology applied with 39 offset wells fractured using standard technology. The average fracturing job size was more than 300 tons of proppant. The comparison reveals the advantage of a new method of fracturing on accumulated oil production (more than 10%); the increased production was mainly due to reduction of the water cut. At the same time, channel fracturing costs are lower by 12% compared to standard fracturing. Such a significant reduction in costs for large-tonnage jobs was achieved by decreasing of material volume for fracturing. The required proppant amount is decreased by 45% due to the specificity of the channel technology. In addition, due to the aggressive proppant concentration, increasing the volume of the required fracturing fluid is avoided, so costs for its delivery and heating are minimized. The application of the new fracturing technology significantly increased the profitability of the Achimov development.

The Achimov formation has been well explored geologically, but there have been few projects that demonstrably increased the profitability of development of these hard-to-recover reserves. This paper presents in detail an effective method for increasing the economic component in the development of hard-to-recover deposits. The potential of the Achimov formation in Western Siberia is significant, and the experience of channel fracturing at the Prirazlomnoye field can be applied to many other oil fields due to the reliability and adaptability of this fracturing technology.