Wells – With below and above ground modification – With receptacle for insertion into well
Reexamination Certificate
2000-02-04
2002-03-12
Schoeppel, Roger (Department: 3672)
Wells
With below and above ground modification
With receptacle for insertion into well
C166S154000, C166S370000, C166S372000, C166S374000, C417S171000, C417S172000, C417S177000, C417S178000, C417S198000
Reexamination Certificate
active
06354371
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to downhole pump for subterranean wells and more particularly to fixed (conventional) hydraulic jet pump assemblies. More specifically this invention relates to a fixed jet pump having nozzle and throat which may be removed from the well without pulling the well tubing and having pressure sensors integrated into the pump assembly.
BACKGROUND OF THE INVENTION
Hydraulic jet pumps have been a recognized and accepted tool for artificial lift in oil and gas wells for many years. When a well no longer has sufficient reservoir pressure to flow under its own power either to the surface or to flow to the surface at a satisfactory production rate, hydraulic pumping may be an option for lifting the fluid from the wellbore to the surface and through the surface facilities. Hydraulic pumping systems transmit stored potential energy contained in a pressurized source of power fluid to stored potential energy in produced fluids and ultimately to kinetic energy in produced fluids. The power fluid may be part of an open system and originate from the well, such as produced oil or produced water, or the power fluid may be confined to a closed loop system.
A popular hydraulic pump is the jet pump which operates by transferring the energy from a pressurized high velocity jet of power fluid directly to produced fluids drawn into the jet stream by a venturi effect created by the high velocity stream. Produced fluids are mixed with the power fluid and the mixture is lifted to the surface by the hydrostatic energy remaining in the mixture after mixing. Hydraulic jet pumps substantially involve no downhole moving parts. If the pressure drop on the produced fluid stream into the jet pump is sufficiently great, a suction may actually be created upon the face of the producing formation at the wellbore. Therefore, jet pumps may also be known as formation suction pumps.
Hydraulic jet pumps are dynamic pumps, as are electric submersible pumps and are to be distinguished from hydrostatic pumps such as reciprocating rod pumps. The objective in jet pumping is to create as much bottom hole pressure draw-down as possible in order to obtain maximum production rate. By altering the variable sizes of component parts, power fluid rate and pressure, jet pumps are capable of producing wells at produced fluid rates from less than 50 barrels of fluid per day (BFDP) to in excess of 10,000 BFPD. As such, in order to optimize system efficiency or resize pump components to adjust to changing well capabilities, it may be necessary to remove a pump rather frequently to make these adjustments. Cavitation, turbulence and friction may become excessive and result in operating inefficiencies in improperly designed jet pump systems, leading to excessive horsepower requirements and component wear. Depending upon the installation design, these problems may require pulling the power fluid tubing string from the well, and/or a production tubing string, and/or the jet pump assembly. In some installation designs the entire pump may be pumped to the surface by reversing flow of the produced and power fluid streams.
There are basically two distinct types of jet pumps. The first may be known as “fixed pump” installations and the second may be known as “free pump” installations. In “fixed pump” installations, the jet pump is run in the wellbore affixed to the power fluid tubing string. There are substantially two basic designs of fixed pump installations. In the first fixed pump installation, the jet pump is attached to the power fluid tubing string and the pump and power fluid tubing string are run inside of a larger tubing string, referred to as the production tubing string, and the pump is landed on a seating shoe which is attached near the bottom of the production tubing string. In this “insert” type installation, power fluid may traverse down the inner power fluid tubing string, pass through the pump and the mixture of power fluid and produced fluid may be transmitted to the surface through the annulus between the two tubing strings. Alternatively, the fluid directions may be reversed. In this insert type, fixed jet pump installation, free gas may be vented up the annulus between the outer production tubing string and the casing. In addition, this installation may allow a larger diameter pump to be run in relatively small casing sizes. Power fluid strings in this installation may typically range in size from ¾ inch to 1¼ inches, depending upon rate, pressure and production tubing size.
In the second fixed pump installation, the jet pump may be run in the wellbore on the power fluid tubing string and include a pack-off device, such as a packer, to seal between the power fluid tubing string and the well casing. Power fluid may typically travel down the power fluid tubing string, pass through the pump and return to the surface with the produced fluid, up the tubing/casing annulus. In this installation, produced gas must be handled by the pump. Therefore, this installation may typically be most applicable to well having low gas volumes and to wells having a relatively high production capacity.
In “free pump” installations, a relatively large tubing string may be run into a wellbore. A bottom hole assembly including a packer and standing valve may be run into the wellbore, concentrically through the larger tubing string, either on a smaller diameter, power fluid tubing string or on wireline. The packer may then be set in the annulus between the tubing strings and above the casing perforations. The “free pump” may then be circulated into the wellbore through the inner, power fluid tubing string and landed on the standing valve. Mixed power fluid and production fluid may then be produced to the surface through the annulus between the two tubing strings. The jet pump may be circulated out of the wellbore as desired to change or resize components in the pump by reversing the fluid directions, causing the standing valve ball to seat in the standing valve.
A free pump may also be retrieved by wireline operations. The free pump type casing installation may also be advantageous where production or power fluid may be transmitted through the wellbore casing, in that this installation only requires the purchase of one tubing string. A significant difference in the free pump casing installation and the fixed pump casing installation is that in the fixed pump casing installation the jet pump is attached to the power fluid tubing string and in the free pump installation the jet pump fits inside of the power fluid tubing string allowing the free pump to be circulated up and down the power fluid string.
In either the free pump installation or the fixed pump installation, the direction of flow for the power fluid and the mixed power and produced fluids may be in either direction such that the power fluid may be selectively transmitted down either the inner tubing string, or down the annulus between tubing strings or between the tubing casing annulus. However, internal components of the jet pump must be directionally oriented to properly accommodate the selected operating practice.
Technical references to jet pumps are known as far back as 1852, however, the first suggestion of an application to pumping oil wells, with a mathematical approach, was first disclosed in 1933. In 1864 Anger and Crocker were granted U.S. Pat. No. 44,587, on a jet pump. McMahon received six patents on oil well pumps beginning in 1930 with U.S. Pat. No. 1,799,483. Jet pumps began to achieve more accepted usage and with emphasized marketing in the oil patch in the 1970's. U.S. Pat. No. T961,006 was granted to Brown in 1977, disclosing a method of controlling cavitation in jet pumps by high pump submergence below the producing formation, in a wellbore. A significant drawback to this invention is that it may require additional cost to drill, case and complete additional rat hole below the producing formation. In 1980, Roeder was granted U.S. Pat. No. 4,183,722, disclosing a jet pump including a conical defl
Browning Bushman
Schoeppel Roger
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