Channel Fracturing Applied in Mature Wells in Western Siberia
Authors: Carpenter Chris 
Published: February 2015

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 159347, ’First Channel Fracturing Applied in Mature Wells Increases Production From Talinskoe Oil Field in Western Siberia,’ by Rifat Kayumov, SPE, Artem Klyubin, SPE, Alexey Yudin, SPE, and Philippe Enkababian, SPE, Schlumberger, and Fedor Leskin, SPE, Igor Davidenko, SPE, and Zdenko Kaluder, SPE, TNK-BP, prepared for the 2012 SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition, Moscow, 16-18 October. The paper has not been peer reviewed.

The new channel-fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude. The channel-fracturing technique allows development of an open network of flow channels within the proppant pack, enabling fracture conductivity by such channels rather than by flow through the pores between proppant grains in the proppant pack. The successful implementation of the channel-fracturing technique in brownfield development is described in detail with the case study of the Talinskoe field in Russia.

Introduction

The Talinskoe section (for simplicity, referred to herein as the Talinskoe field) is part of the medium-sized, mature Krasnoleninskoe field, located near Nyagan, Russia. Exploration of this section began in 1982. It has more than 5,000 wells completed either in the Middle Jurassic Tyumenskaya suite (Formations JK2 through JK9) or the Early Jurassic Sherkalinskaya suite (Formations JK10 through JK11). More than 1,500 wells have been fractured hydraulically. Approximately 60% of all wells are idle, mainly because of water breakthrough (the average water cut throughout the field is 90%). Most hydrocarbons are found in the Sherkalinskaya suite, but, currently, water cut in many wells producing from the JK10 and JK11 formations already exceeds the economic limit. These wells are recompleted to produce from shallower formations in the Tyumenskaya suite.

The Tyumenskaya suite is characterized by a complex geology. It is an argillaceous facies with sandstone sublayers and lenses. Because of low permeabilities in the Tyumenskaya suite, most of the wells cannot be produced commercially without stimulation. To enhance well productivity in such conditions, the greatest possible fracture length is required, but it is not always possible to achieve targeted half-length because of geological limitations and formation mechanical properties. While designing for the greatest length possible, the engineer is frequently limited by low-to-moderate stress contrast between the target formation and the barrier separating the target interval from the possibly watered-out formation.

It is usually not a problem in low-permeability reservoirs to achieve target dimensionless fracture conductivity (DFC) greater than 2. But this does not always provide the best productivity results. Thorough analysis of the 3-year fracturing campaign in Nyagan showed that a DFC greater than 15–20 should be targeted for this region. Lower DFC values result in lower productivity. Lack of control over fracture-height growth (with the subsequent reduction in fracture width) is a possible reason for production underachievement.