Text 8 Facility Layout
Onshore
Onshore wells are normally drilled vertically, so their wellheads are scattered over the field’s surface. Flowlines radiate inward, connecting each well to a manifold at the central tank battery. Wellhead pressure, either naturally occuring or generated by artificial lift equipment, moves the produced fluids through the flowlines and tank battery.( Figure 8.1 )
The manifold valves are opened and closed to send one well at a time through the well test system, where the well’s production rate of oil, gas, and water is measured. Production of all the other wells is directed through the normal production system.
The oil, gas, and water are separated by gravity segregation. Emulsion-breaking measures are usually required.
The oil is metered and sold, usually through an ACT, into the purchaser’s pipeline or tank truck.
The gas is sold by metering its volume through an orifice meter and its composition is periodically checked to determine the content of ethane and heavier hydrocarbons. The unit price of the gas is then adjusted to reflect the additional heat content.
This rich (high content of heavier hydrocarbon vapor) and wet (high water vapor content) gas cannot be transported very far before it cools and condenses liquid out in the pipeline or forms gas hydrates. From the tank battery, the gas is therefore pipelined to a nearby natural gas processing plant where the hydrocarbon liquids and water are removed and the residue gas is compressed into the sales pipeline.
The produced water, which is usually too salty to be dumped into surface waters, must be disposed of into subsurface formations. If there is a waterflood in the vicinity, the water can be put to valuable use.
Figure 8.1 Onshore tank battery.
Glossary
Gravity segregation. Separation of fluids by the force of gravity, which draws the denser material downward, forcing the lighter material upward.
Orifice meter. Determines gas flow rate by measuring the pressure drop incurred by the gas in passing through an orifice.
8.2 Comprehension questions:
Why are onshore wells drilled vertically?
What moves the produced fluids through the flowline and tank battery?
Where is the well’s production rate of oil, gas, and water measured?
What is the oil sold through?
What is the gas sold through?
Can rich and wet gas be transported very far?
8.3 Give Ukrainian correspondences:
wellhead pressure; produced fluids; tank battery; manifold; emulsion-breaking; ACT; hydrocarbons; rich gas; wet gas.
8.4 Make 3 sentences using the above mentioned words.
8.5 Fill in the blanks using the following:
subsurface completions, flow lines, tension-leg platforms, individual jackets, the development scheme, individual flowlines, bottom-supported platforms, pipelines.
1 _________________ in shallow water is identical to onshore.
2 ______________ are set and the wells are drilled vertically.
3 Long ____________ connect them to a central platform where processing takes place.
4 With _________________, the wells are remote from the facilities but connected by ______________ or by __________ serving several wells.
5 The surface facilities can be mounted on ___________________ or floaters such as __________________ or FPSOs.
8.6 Translate into Ukrainian:
Whether on land or offshore, all flowlines come together at the “ manifold ”- the first segment of the central processing train; this piping and valving station switches the flow from any well or group of wells into one of multiple “ headers ”.
Three-phase separators that divide the production into three streams - oil, water and gas - are sometimes used with high-gravity oils that readily separate from the water.
Wash tanks, or gunbarrels, are large tanks used to provide a great deal of quiet retention time for the water to settle out of the crude and be drawn off the bottom.
Tanks are large vessels used for volume storage of oil or water or to provide retention time for gravity segregation; although storage tanks are not constructed to contain pressure, a few ounces of gas pressure is normally maintained to exclude air.
Vapor recovery units capture the low pressure gas that continues to vaporize out of crude oil as it passes through gun barrels, stock tanks, etc.
8.7 Retell Text 8
9.1 Read and translate Text 9