"Roughly 35 per cent of all "in situ" production in the Alberta oil sands uses a technique called high pressure cyclic steam stimulation (HPCSS), which cycles between two phases: first, steam is injected into an underground oil sands deposit to fracture and heat the formation to soften the bitumen just like CSS does, excepting at even higher pressures; then, the cycle switches to production where the resulting hot mixture of bitumen and steam (called a "bitumen emulsion") is pumped up to the surface through the same well, again just like CSS, until the resulting pressure drop slows production to an uneconomical stage. The process is then repeated multiple times." An Alberta Energy Regulator (AER) news release explained the difference between high pressure cyclic steam stimulation (HPCSS) and steam assisted gravity drainage (SAGD). "HPCSS has been used in oil recovery in Alberta for more than 30 years. The method involves injecting high-pressure steam, well above the ambient reservoir pressure, into a reservoir over a prolonged period of time. As heat softens the bitumen and water dilutes and separates the bitumen from the sand, the pressure creates fractures, cracks and openings through which the bitumen can flow back into the steam-injector wells. HPCSS differs from steam assisted gravity drainage (SAGD) operations where steam is continuously injected at lower pressures without fracturing the reservoir and uses gravity drainage as the primary recovery mechanism."