Massive Hydraulic Fracturing – A Case History in Western Siberia, Russia

Abstract

Hydraulic fracturing has been the choice for well stimulation in Russia to enhance production for quite some time now. It was not until recently the treatment design has increased in size and magnitude in order to heed the country's aggressive production enhancement strategy to meet the local and international demand. The focus of this paper is to discuss the technical and operational applicability of Massive Hydraulic Fracturing (MHF) strategy to enhance production in the Russian oil fields. A case history of the first well that was treated with MHF is provided. The well reflects the large majority of Russian oil wells, especially in the Western Siberian region, which have tremendous potential to enhance production via this strategy. The well falls in the low to intermediate permeability category (less than 1 to 50 md), which can often be converted to be excellent high producing wells by effective hydraulic fracturing technology coupled with proper artificial lifting system. A comprehensive technical analysis of the well before and after the treatment is provided. This includes production analysis using decline and/or type curve analysis before and after treatment, formation evaluation, well performance analysis to estimate the incremental gain, and forecasting. The design and operational aspects of the hydraulic fracturing treatment is also discussed. The results were encouraging. The production increased by more than double after the hydraulic fracturing treatment with relatively low water cut to date. The well was able to flow naturally after the treatment for a few months before artificial lift is installed. Introduction Hydraulic fracturing has been an established choice for well stimulation in Russia to enhance production. Recently, the size and magnitude of fracturing treatments have increased in order to keep pace with the country's aggressive production enhancement strategy. In Sibneft, the fracturing treatment size has increased from an average of 22 tons up to more than 80 tons of proppant. The treatment size is increasing steadily from small to medium scale for the last three years, and recently, to the point of massive. The definition of Massive Hydraulic Fracturing (MHF) is rather arbitrary as reported in several published literatures pertaining to the subject.1–8 In general, MHF simply refers to very large treatments, typically an order of magnitude larger than the conventional fracturing procedures. In Russia, MHF is referred to as having a treatment of more than 150 tons of proppant. The main goal of MHF is to expose larger surface area of the low-permeability formation, compared to the conventional procedures, to flow into the wellbore, thereby significantly increase well productivity. This paper discusses the technical applicability, including the operational feasibility of deploying massive fracturing strategy, to aggressively enhance production in the Russian oil fields. The main focus is to demonstrate via case history that MHF can strategically be adopted as one of the techniques to stimulate wells and rapidly enhance production in Russia; especially for the oil fields in the Western Siberian region. A documented case history of one of the first wells treated with MHF in Russia is provided in order to show the applicability of the strategy. Well 1102 from Pad 153 of Vyngayakhinskoe field, BP12 formation, has been selected in this analysis. The well is one good example to reflect the characteristics of large majority of Russian oil wells, which falls in the low to intermediate permeability category of less than one up to 50 md. A comprehensive and systematic well performance analysis using production type curve and analytical transient solution models, before and after the treatment is discussed. This includes discussions of fracture design and issues associated with the workover and optimization operations. Field and Formation Descriptions Vyngayakhinskoe field is located in the Western Siberian region. It is an upper cretaceous undersaturated reservoir, which comprised of three major productive formations, BP11, BP12, and BP16. The main focus of this paper is on the BP12 formation, where production development and enhancement activities have been quite active recently. The map and the regional location of the wells producing from BP12 formation are shown in Figure 1. There is only one injector in the region, which is located 400 m to the north of Well 1102. All other wells in the vicinity are oil producers.

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