Canada’s heavy oil reserves, estimated a 1.7 to 2.5 trillion bbl of oil in place, are an increasingly important source of supply, in part because technology advances have significantly reduced production costs and increased recovery. Bornemann multiphase pumps have been used successfully to help meet these goals by collecting gas from the wellbore annulus to reduce back pressure and provide additional revenue.
Steam injection processes are used as both primary and secondary recovery methods for heavy oil deposits around the world.
The most common methods are steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS). Both processes subject equipment to high temperatures, acid gases and steam.
The cyclic steam, or “huff and puff,” stimulation process requires only one wellbore. Each cycle consists of two phases. Steam is first injected for several weeks to heat the oil. Then during the production phase, the oil will flow into the wellbore where it is lifted to the surface, typically with beam pumping units.
Another injection cycle is begun when reservoir cooling causes production to fall below an acceptable level.
Steam assisted gravity drainage (SAGD) requires two horizontal wellbores spaced closely in the reservoir. Steam is injected continuously into the upper wellbore, mobilizing the oil to drain to the lower wellbore where it is pumped to the surface. A typical well stream includes saturated steam and condensed water; small amounts of bitumen; and gas, including methane, CO2 and H2S.
When multiphase pumps are used to collect wet gas from the casing annulus:
- Gas composition can shift from an 80/20 CO2/methane ratio to a ratio of 20/80;
- Inlet temperature is near that of saturated steam, about 130 °C.;
- 20-30 wells are drilled from a single pad, and total gas production from the pad may reach 30,000 sm3/d (1 MMscf/d);
- A multiphase pump can also be used to transfer total production from the pad.