As early as 1928, reservoir engineers were giving serious consideration to gas-energy relationships and recognized the need for more precise information concerning physical conditions in wells and underground reservoirs. Early progress in oil recovery methods made it obvious that computations made from wellhead or surface data were generally misleading. Sclater and Stephenson described the first recording bottom-hole pressure gauge and a mechanism for sampling fluids under pressure in wells.3 It is interesting that this reference defines bottom-hole data as measurements of pressure, temperature, gas-oil ratio, and the physical and chemical natures of the fluids. The need for accurate bottom-hole pressures was further emphasized when Millikan and Sidwell described the first precision pressure gauge and pointed out the fundamental importance of bottom-hole pressures to reservoir engineers in determining the most efficient oil recovery methods and lifting procedures.4 With this contribution, the engineer was able to measure the most important basic data for reservoir performance calculations: reservoir pressure. *Taken from : http://www.informit.com/articles/article.aspx?p=2241145&seqNum=2
In the practise of reservoir engineering, the reservoir engineer determines the properties of the reservoir matrix and of its fluids, interprets these data in terms of reservoir-fluid behaviour, and recommends the development and production program that will result in maximum economic recovery of hydrocarbons – spacing of wells, gas-oil and water-oil ratios, rate of prduction, stimulation procedures, pressure control program. An important side function of reservoir engineer is the prediction of hydrocarbon recovery that can be anticipated under recommended conditions of development and production, including secondary recovery and artificial lifts.. The application of information for increasing recovery of oil and gas provides the reservoir engineer with the oppurtunity to make his greatest contribution to the industry.