Wells – Processes – Assembling well part
Reexamination Certificate
1998-05-01
2001-05-15
Tsay, Frank S. (Department: 3672)
Wells
Processes
Assembling well part
C166S117500
Reexamination Certificate
active
06230812
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to side pocket mandrels for use in well tubing strings or production tubing in a well bore. More particularly this invention relates to side pocket mandrels and methods of construction thereof for use in coupling one or more electrical conductors from a side pocket mandrel to the earth's surface for obtaining real time downhole measurements and data.
BACKGROUND OF THE INVENTION
Side pocket mandrels are typically installed in a string of production tubing in a well bore. The mandrel is provided with a full opening bore which is aligned with the bore of the production tubing and with a laterally offset side pocket bore which receives a side pocket well tool. Side pocket well tools can be passed through the production tubing and are retrievably seated in the side pocket bore to perform or to monitor operations in the well bore or production tubing. A side pocket well tool is retrievable and can be seated and recovered from the offset bore by use of a kickover tool, or similar tool. Side pocket well tools heretofore typically have included flow control devices, gas-lift devices, chemical injection devices and so forth, for use in conventional production operations.
In a typical construction, the side pocket mandrel has a mandrel body section with the full opening bore and the body section is connected to forged upper and lower body sections by butt welds. To latch a tool in an offset side pocket bore, a valve latching lug or clamp is located in the mandrel body to cooperate with the side pocket well tool. Welding usually requires that the assembly be heat treated to relieve stress.
In some instances, a desire has been expressed to have an single wire electrical take out from a side pocket mandrel for data transmission to the earth's surface. This can be difficult because of welding and heat treatment which can destroy or adversely affect any electrical components. Further, even when separately installed, a bottom located electrical take out is difficult because the wire is easily damaged when the production string is moved through a well bore.
In the present invention the system for manufacturing a side pocket mandrel and its construction permits an electrical takeout at the top of the mandrel and/or the bottom of the mandrel and permits installation of an inductive coupling device in the lower end of the mandrel.
One purpose of an electrical takeout on a side pocket tool is to monitor the pressure of the fluids over a period of time as a function of real time by connection of a downhole pressure measurement tool with an electrical conductor extending to the earth's surface for data transmission. In present systems to obtain a real time pressure measurement, a pressure gauge is attached to the exterior of the string of tubing. The gauge, the tubing and an attached electrical conductor wire are located in a well bore. Should a problem arise with the tool or for any other reason which might require removal of the tool, the well must be killed and the gauge retrieved with the string of tubing. Obviously, this is expensive and time consuming.
A proposed system, such as described in the OTC paper 5920, 1989 entitled “A Downhole Electrical Wet Connection System For Delivery and Retrieval of Monitoring Instruments by Wireline” uses a side pocket mandrel and pressure gauge with a downhole “wet connector” for coupling power to a tool and for read out of data. “Wet connectors” in a high pressure, corrosive environment ultimately corrode. In making up the connection, it is often difficult to make connections because of mud or debris in the well bore. Moreover, brine in the fluid causes electrical shorting of circuits. In short, an electrical wet connector is not reliable and this is particularly true over a period of time.
In another type of system known as a “Data Latch” system, a battery powered pressure gauge is installed in a mandrel which has a bypass. A wireline tool with an inductive coil is latched in the bore of the mandrel while permitting a fluid bypass. The inductive coil on the wireline tool couples to a magnetic coil in the mandrel for obtaining a read out of real time measurements. The system does not provide downhole power to the tool and battery failure requires killing the well and retrieving the tool with the well string.
Inductive coupling devices are difficult to construct for a downhole environment and yet are extremely desirable devices for downhole tools as a replacement for the above systems. Moreover, a system for real time measurement and monitoring of pressure, flow velocity, and temperature on a more or less permanent basis is highly desirable.
SUMMARY OF INVENTION
In the present invention a side pocket mandrel is an integral assembly with a lower end section, a side pocket housing section, and an upper takeout section where said sections are seelingly interconnected and define a full opening bore in alignment with a longitudinal axis of a production tubing. The side pocket housing section has a full opening bore and an offset side pocket bore which is laterally offset with respect to the full opening bore. The side pocket bore is constructed and arranged to receive a side pocket well tool with a tool inductive coupling member and includes a guide channel above the side pocket bore.
The assembly includes a side pocket inductive coupling member fixed in the lower end of the offset side pocket bore to receive the tool inductive coupling member and to provide an inductive coupling relationship so that electrical power can be provided to a well tool in the side pocket bore and data transmission can be made from the well tool to the side pocket inductive coupling member. The full opening bore in the side pocket housing section is continued through the lower end housing section by a tubular member which defines a chamber between the outer wall of the tubular member and the inner wall of the end housing section.
The side pocket induction coupling member has an electrical wire disposed in a pliable tubing conduit which extends into the chamber and through a longitudinal bore in the side pocket housing. The longitudinal bore in the side pocket housing is coupled by a tubular longitudinally extending pipe member to a take out bore in the upper take out section. The tubing conduit extends through the pipe member and the take out bore and is connected to an electrical pressure connector at the upper end of the side pocket mandrel.
In assembly, the tubing conduit in the side pocket mandrel and the connected side pocket inductive coupling member are jointly shifted to move the side pocket inductor coupling member into the side pocket offset bore while moving the tubing conduit exterior to the take out housing. When the tubing conduit is exterior to the take out housing, the electrical pressure connector can be connected up to the tubing conduit. Then the tubing conduit and the connected side pocket inductive coupling member are jointly shifted to a position where the electrical pressure connector is pressure connected in the take out housing and the inductive coupling member is located in its operative position in the side pocket bore. The electrical connector is enclosed in a chamber by a tubular member which is located in the lower housing section. A threaded end member is sealingly attaches to the lower housing section and provides a continuation of the full opening bore with the tubular member.
The various sections of the side pocket mandrel can be connected by welds which can be heat treated independently of installation of the inductive coupling member so that the coupling member is not adversely affected by a heat treatment. In forming the welded joints, the adjacent ends to be welded are provided with an exterior welding chamfer and internal wall recesses. When welded together, the mating recesses provide a full flushing recess at each welded connection.
REFERENCES:
patent: 3939705 (1976-02-01), Glotin et al.
patent: 4105279 (1978-08-01), Glotin et al.
patent: 4333527 (1982-06-01), Higgins
patent: 4416330
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