Prospects Of Eor Techniques In Saskatchewan Oil Reservoirs

Abstract

Abstract The heavy oil deposits of the Lloydminster area of Alberta and Saskatchewan represent a vast resource (3.5 billion m3 or 20 billion barrels) of great importance to Canada. Unlike the oil sands of Alberta, these oils are mobile at reservoir conditions, and thus more easily recoverable. However, these pose problems of their own: the reservoir quality is inferior the oil recovery technology is yet to be proven for the great majority of the fields, and as yet facilities for upgrading of the produced oil are non-existent. It is believed that variations of steam injection and wet in-situ combustion and immiscible carbon dioxide flooding will help produce a sizable fraction of heavy oil in Saskatchewan. However, a great deal of laboratory research and field-testing will be needed in order to double the present heavy oil production over the next ten years, which was the goal set in 1980. Development of enhanced oil recovery is a slow process, which cannot be speeded up simply by infusion of capital. It is clear that the present pace of EOR activity in Saskatchewan, while encouraging, is too slow to meet Saskatchewan Energy and Mines' (SEM) 1982 projections. Introduction The heavy oil deposits of the Lloydminster area have an everincreasing importance in Canada's energy picture. The inplace oil is estimated at about 3.5 million m3 (20 million barrels) – possibly three times as much. Unlike the oil sands of Alberta, the oil in these reservoirs is mobile at the prevailing conditions. The primary recovery is 5% to 10% of the in-place oil, with an additional few per cent by waterflooding. As a result, unlike the oil sands of Alberta, fluid injectivity and productivity and inter-well communication are not problems in the Lloydminster reservoirs. In recent years, both the success in the Lloydminster pilots and the limited success in the oil sands projects have served to underscore the importance of the Lloydminster deposits. It is certain that with increased field activity and laboratory research, very large volumes of oil can be produced from these reservoirs. Canada's conventional oil reserves are about 1.2 million m3 (8 billion barrels); the current oil production is about 200 000 m3/day, while the consumption is 260 000 m3/day. The impact on the Canadian economy is about $12 billion per year – some three times the actual cost of the imported oil. The Lloydminster heavy oil is playing a vital role in reducing this deficit. General Features of the Lloydminster Reservoirs Numerous fine papers by Vigrass(1) and others have discussed the geology and the basic characteristics of the Lloydminster area reservoirs. These reservoirs are usually small in size, and have been described as "islands of sand in a sea of shale". The oil gravity varies from a high of 22 – 23 API (Wainwright, Taber W) to 14 – 16 API (Bonnyville) to 9 API (Onion Lake). The in-place oil viscosity varies from 150 to 4000 mPa.s, with 2000 average. The oil saturation is usually very high about 80% and the porosity is 35%.