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→Mechanical failures
==Mechanical failures==
==Mechanical failures==
[[file:production-problems_fig4.png|thumb|{{figure number|4}}Examples of mechanical failure.]]
Mechanical failures can occur in a well for a variety of reasons. They are usually related to one of the following: (1) the corrosion of downhole equipment, (2) the collection of debris or scale in the wellbore, (3) the production of formation sand or collapse of the formation, (4) insufficient cement protection, or (5) the use of equipment that is not designed to withstand the depth, temperature, or pressure of a well.
Mechanical failures can occur in a well for a variety of reasons. They are usually related to one of the following: (1) the corrosion of downhole equipment, (2) the collection of debris or scale in the wellbore, (3) the production of formation sand or collapse of the formation, (4) insufficient cement protection, or (5) the use of equipment that is not designed to withstand the depth, temperature, or pressure of a well.
The type of equipment normally prone to such failure is the tubing, casing, rod string, downhole pumps, packers, gas lift valves, and plugs in the wellbore (Figure 4). After long-term exposure to downhole conditions, breakage or wear can occur in any of this equipment. Extensive workovers (specifically, [[fishing]] operations) can be prevented by regular maintenance of the downhole equipment (see “[[Workovers]]”). A proper maintenance schedule can be established for any field once one has properly analyzed the produced fluids and conditions of the reservoir.
The type of equipment normally prone to such failure is the tubing, casing, rod string, downhole pumps, packers, gas lift valves, and plugs in the well bore ([[:file:production-problems_fig4.png|Figure 4]]). After long-term exposure to downhole conditions, breakage or wear can occur in any of this equipment. Extensive workovers (specifically, [[fishing]] operations) can be prevented by regular maintenance of the downhole equipment (see “[[Workovers]]”). A proper maintenance schedule can be established for any field once one has properly analyzed the produced fluids and conditions of the reservoir.
Specific diagnostic techniques can be applied in an effort to determine where a failure has occurred. For example, a casing leak can be detected by running a packer in the well and pressure testing the casing at various intervals in the hole. Problems with rod pumping equipment can be diagnosed through the use of an instrument called a ''dynamometer''. This instrument analyzes the strain on the polish rod at the surface as the pump goes through an upstroke and downstroke cycle. Other diagnostic methods are available, and in some instances, it may be necessary to perform several tests before mechanical problems can be pinpointed.
Specific diagnostic techniques can be applied in an effort to determine where a failure has occurred. For example, a casing leak can be detected by running a packer in the well and pressure testing the casing at various intervals in the hole. Problems with rod pumping equipment can be diagnosed through the use of an instrument called a ''dynamometer''. This instrument analyzes the strain on the polish rod at the surface as the pump goes through an upstroke and downstroke cycle. Other diagnostic methods are available, and in some instances, it may be necessary to perform several tests before mechanical problems can be pinpointed.