Workable and economical equipment is available today to give automation from the wellhead to the pipeline. This automation can be most readily divided into three groups of equipment: Group 1, "Flowing and Production Controls";Group 2, "Well Testing"; and Group 5, "Custody Transfer". Let us examine each of these groups separately to determine the requirements of each.
These controls are required to regulate flow from the wellhead to the flowline, pressure control in the flow line and production equipment, level control in the production equipment, and temperature control where required. Access from wellhead to pipeline is provided through valving on flowing wells and through the pumping unit for wells on pump. The automation controls require dare used to shut-in the well when required by a preset program or in response to an alarm condition. The normal pressure, level, and temperature controls used on the production equipment are included in the alarm system.
An automated lease usually consists of several wells being produced into a central production facility. For ease of handling it is usually expedient to locate several flow diverter valves connected together into a manifold for the purpose of routing the fluids from the wellhead to either production or test facilities. Where flowing wells are manifolded together, it is often practical to use three-way, three-position valves for the purpose of shutting in the well.
It is an exception for this three-position valve to be the only shutoff between the wellhead and the production equipment. It is more common to close both of the outlets of the three-position valve to cause pressure to build up in the flow line. A two-way valve, installed at the wellhead and controlled by a hi-lo pressure pilot, senses this rising pressure and shuts in the well. For leases with relatively short-distance flow lines, a low pressure signal to the hi-lo pressure pilot may be used to indicate a ruptured line, and will cause the pilot to shut-in the well. Thus, the pilot acts as a high and low safety device as well as the means of shutting in the well in accordance with programming or in response to an alarm shut-in condition.
