To complete the well for oil or gas recovery production, casing is set and cemented at the bottom of the well in contact with the oil-bearing sediments. Shell-shaped explosives perforate the casing and cement allowing oil and gas to flow into the wellbore in primary recovery. Natural pressure forces the hydrocarbons up the wellbore to the surface. When the pressure drops it is bolstered by the injection of gas or water in what’s known as secondary recovery. In even the best-run oilfields it is not possible to recover all of the hydrocarbons trapped in the reservoir. Up to ninety percent of gas and forty-five percent of oil is collected in the wellhead area. On a production platform can contain numerous combinations of Valve’s pipes and gauges called Christmas trees. These represent individual production wells drawing oil and gas from one large field the world’s may extend up to five kilometers from the wellhead the well can be turned off by high-powered valves.