Abstract

The Alberta Oil Sands comprise the bulk of Canada's petroleum reserves. The bitumen in these deposits is too viscous to flow naturally and cannot be produced by conventional oilfield techniques. Where the deposits are close to the surface, mining can be employed to recover the Oil Sands. In many areas, however, the over burden thickness is such that in-situ recovery techniques provide the only means of recovering bitumen.

This paper describes the drilling details of a well which will be used in an in-situ recovery pilot at Cold lake. The well, Imp 78 Horizontal Leming Ex 9-6-65-3 was spudded conventionally and then deviated so that its final wellbore path was horizontal in the Clearwater formation. Over 1000' of pay section was contacted by this well in a zone which is only 160' thick. Details about the well planning, drilling equipment, drilling fluid, survey program, casing and problems encountered are discussed.

Introduction

The Alberta Oil Sands are one of the world's largest known reserves of petroleum. The main deposits. Athabasca, Cold Lake, Peace River and Wabasca contain about 900 × 109 barrels, 95% of the petroleum discovered to date in Canada.

The heavy oil in the sands is very viscous and cannot be recovered in its natural state by conventional production methods. The two commercial plants presently in operation surface mine the oil sands and upgrade the bitumen recovered into light oil.

The reserves in the Cold Lake deposit (Figure 1) cannot be recovered by mining techniques because l000' of over burden overlies the oil bearing sands. Here, in-situ recovery methods provide the only means of extracting the heavy bitumen. There are many recovery pilots in operation in the area and most involve the application of external energy, such as steam, to reduce the viscosity of the heavy crude and allow production.

To introduce heat into, the oil sands, vertical or moderately deviated wells are drilled into the oil bearing formation. Because the wells have limited drainage capabilities, the well spacing is closer than in conventional producing fields and large numbers of wells are required.

A well ill which a large section of oil sand can be contacted may provide increases in both production rates and recovery levels. The only means by which such lengths of reservoir can be reached is with a highly deviated well which enters the reservoir at a near horizontal inclination.

Imp 78 Horizontal Leming Ex 9-6-65-3 is such a well. It was spudded conventionally on March 21, 1978 and then deviated so that its final wellbore path was horizontal, 1558 below the surface. This paper discusses the methods and techniques employed to drill this well.

PLANNING
(a) Pre-Program

Esso Resources (formerly Imperial) has operated pilot studies in the Cold Lake area since 1964. Over 100 evaluation wells and 190 pilot related wells have been drilled to date. The initial pilot wells were vertically drilled but more recent wells have been deviated up to 35 ° from vertical.

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