Abstract

Near well-bore electromagnetic heating is a relatively new process designed to reduce oil viscosity and result in improved well productivity. To date most of the tests have been conducted in widely spaced vertical wells.

The Texaco Frog Lake Project will determine the applicability of this technology in three closely spaced wells, drilled from a central pad which deviate up to 60 degrees from the vertical. The test is expected to yield sufficient data on production rates and probable ultimate recovery to permit a reliable economic assessment of commercial expansion. A numerical simulator which has the capability of modelling the temperature effects of electromagnetic heating has been used to predict production rates for the test wells. It is also expected that this test will provide valuable operational data for the design of electrical heating systems for horizontal wells which could further improve production rates and ultimate recovery.

Introduction

The Frog Lake Lease covers an area of 40,907 acres and is located about 50 miles northwest of Lloydminster, Alberta in the southeastern portion of the Cold Lake Oil Sands deposit (Figure 1). The lease contains a number of heavy oil producing horizons within the Mannville Group of the Lower Cretaceous (Figure 2.). There are currently seven wells on primary production: four in the lower Waseca, two in the Dina and one In the McLaren. These horizons typically exhibit localized net pay zones of 3 to 5 meters in thickness; however, primary production rates are generally restricted to less than 5 m3/d/well due in large part to the high viscosity of the oil. The Viscosity problem Is exacerbated in the near well-bore region as the gas comes out of solution in response to the pressure sink near the well. To offset this "visco-skin" effect, operators have usually employed steam to reduce the oil viscosity in the near well-bore region. During the 1960's steam stimulation treatments were carried out on several wells on the Frog Lake lease but based on these tests it was concluded that conventional thermal recovery methods using steam are hampered by the thermal inefficiency associated with the thin sands.

Texaco is now preparing to apply electromagnetic heating to stimulate three Lower Waseca wells at Frog Lake. The electromagnetic heating process to be applied was patented by Bridges et al of the IT Research Institute, Chicago Illinois in 1983. Initial field tests were undertaken at Ardmore, Oklahoma in 1985 and during the past two or three years several additional tests have commenced in the U.S.A., Canada, the Netherlands, and Brazil.

The Alberta Oil Sands Technology and Research Authority (AOSTRA) has agreed to participate in the project which will utilize three closely spaced devialed wells drilled Irom a central pad. The wells were placed on production in late November 1990 and electromagnetic heating is scheduled to commence by mid 1991 when sand cuts in the wells are expected to have declined and construction of the required three phase power supply lines will be complete.

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