Abstract

A major Russian operator has encountered operational risks and challenges in oil production due to the highly diverse reservoir properties of Siberian fields. The majority of the operator's east and west Siberian fields include heterogeneous sandstones with low to high permeability, complicated geological and stratigraphic cross-sections and an active bottom water aquifer. In some areas, a gas cap is one of the drive mechanisms.

Horizontal wells tend to become more popular in both green and brown fields because of improved recovery efficiency due to increased reservoir drainage area. However, unbalanced inflow profiles along horizontal sections can result in early water/gas breakthrough which shortens well life and decreases overall profitability.

This paper will describe the application of inflow control technology in two Siberian fields (one with a sand control issue), addressing early water and gas breakthrough caused by intensive water injection and a massive gas cap. Production is optimized by ensuring uniform inflow profile along lateral sections and minimizing annular flow. The setting selection process for inflow control devices and the integration of reservoir analysis with well completion are detailed. The resulting delay of water/gas breakthrough in these horizontal wells leads to enhanced recovery efficiency and improved productivity.

Introduction

Inflow control devices which delay and control early water and gas breakthrough, minimize annular flow and equalize inflow across the reservoir have been used successfully in the UK and Norway sectors of the North Sea, West Africa, Australia, Abu Dhabi and Saudi Arabia. This paper will document the first applications of in-flow control devices in Siberian fields.

The applications to be discussed are designed for horizontal completions ranging in length from 600 meters to 1,000 meters. In some cases reservoir information was limited; however, despite this lack of information, the decision was taken to run the completions that incorporate premium sand control technology for added assurance against potential - and where applicable - real sand production issues. The authors will discuss the inflow control device and sand control technology selection process, integrated completion and reservoir analysis, and an operations summary. The successful deployment and application of inflow control devices in western and eastern Siberia highlights the introduction of new reservoir management and sand control technology into Russia. These field developments clearly illustrate how new technology and paradigm changes to completion methodologies can be used to overcome the technical and operational challenges inherent in working in remote locations under demanding geological and geographic conditions.

Two Siberian fields were selected for ICD installations. Komsomolskoe, a mature field in western Siberia was established in 1986 in the Yamalo-Nenets Autonomous District of Western Siberia, near the town of Gubkinsky. In 2006, the operator began utilizing new drilling technology which resulted in a move from traditional vertical drilling to horizontal drilling. As a result, horizontal wells between 600 and 700 meters are now being drilled in the field. Horizontal drilling enabled the company to achieve an increase in the average flow of new wells to over 100 tons per day and also allowed production to start from previously undeveloped strata at the Komsomolskoe field. The Komsomol BP-2 layer was selected for completion in the Komsomolskoe field.

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