Production methods Made by Kauynbay Aiganym 2 nd year student FOGI Checked by Nadir A. T.
The hydrocarbon fluids are under pressure because of their depth. Depending on the original characteristics of hydrocarbon reservoirs, the type of driving energy is different.
Types of reservoir energy: Energy of compression of the water and rock within the reservoir Energy of compression of oil within the reservoir Energy of compression of gas within the reservoir Energy of compression of waters contiguous to and in communication with the petroleum reservoir Gravitational energy that causes the oil and gas to segregate within the reservoir
1. Solution Gas Drive Reservoirs Crude oil under high pressure may contain large amounts of dissolved gas Recoveries are low, on the order of 1015 % of the original oil in place (OOIP). Usually good candidates fro waterflooding
Distribution of water, oil, and gas in a solution-gasdrive reservoir: (a) before production and (b) during depletion.
2. Water drive reservoir Most oil or gas reservoirs have water aquifers. The pore spaces vacated by oil or gas produced are filled by water. Recovery efficiencies of 70 to 80 % of the original oil in place (OOIP) are possible in some water drive reservoirs.
Distribution of water and oil and position of water/oil contact (WOC) in a water drive reservoir (a) before production and (b) during depletion.
3. Gas-cap reservoir In gas cap drive reservoirs, wells are drilled into the crude oil producing layer of the formation. As oil production causes a reduction in pressure, the gas in gas cap expands and pushes oil into the well bores.
Distribution of water, oil, and gas and position of gas/oil contact (GOC) in a segregating-gas-cap reservoir: (a) before production and (b) during depletion.
Gravity drainage reservoir Gravity drainage is a slow process because gas must migrate up structure or to the top of the formation to fill the space formerly occupied by oil. Gas migration is fast relative to oil drainage so those oil rates are controlled by the rate of oil drainage.
When the natural pressure within the reservoir has dissipated, the drive can be maintained by injecting (a) gas into the gas cap at the top of the reservoir, or (b) water into the aquifer beneath the oil. In some reservoirs both techniques are used at the same time.
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