Magnetic bailer

A bailer is configured to remove particulate solids from fluid passing through the bailer. The bailer preferably includes a housing that includes an intake and an outlet to permit the flow if well fluids through the housing. The bailer also includes a magnetic plate that includes at least one aperture that provides a path for the fluid flow. The bailer optionally includes one or more elongate magnetic bars that extend along the longitudinal axis of the bailer housing. The bailer can be used in conjunction with other components in a downhole pumping system, a surface pumping system or a transport system.

FIELD OF THE INVENTION

This invention relates generally to the field of downhole pumping systems, and more particularly to an apparatus for filtering particulate solids.

BACKGROUND

Submersible pumping systems are often deployed into wells to recover petroleum fluids from subterranean reservoirs. Typically, a submersible pumping system includes a number of components, including an electric motor coupled to one or more pump assemblies. Production tubing is connected to the pump assemblies to deliver the petroleum fluids from the subterranean reservoir to a storage facility on the surface. Each of the components in a submersible pumping system must be engineered to withstand the inhospitable downhole environment.

The efficient recovery of oil and gas from wells depends on maintaining clean formations, casing perforations, lines and pumping equipment. Despite these efforts, many oil wells produce fluids that contain large amounts of particulate solids that can damage downhole components. Various forms of iron sulfide are frequently present in produced fluids and are very hard (6–6.5 Mohs Scale). These hard particles exacerbate wear on downhole components as they are carried through the downhole pumping system with the produced fluid.

It would therefore be desirable to prevent iron sulfide particles from contacting expensive downhole components. Despite the recognition of these problems, prior art attempts to protect downhole components from iron sulfide have been unsuccessful. It is to these and other deficiencies in the prior art that the present invention is directed.

SUMMARY OF THE INVENTION

In a preferred embodiment, the present invention provides a bailer configured to remove particulate solids from fluid passing through the bailer. The bailer preferably includes a housing that includes an intake and an outlet to permit the flow if well fluids through the housing. The bailer also includes a magnetic plate that includes at least one aperture that provides a path for the fluid flow. The bailer optionally includes one or more elongate magnetic bars that extend along the longitudinal axis of the bailer housing.

The bailer can be used in conjunction with other components in a downhole pumping system. In a first preferred application, the bailer is installed in an offset intake pipe that extends through a packer. In a second preferred embodiment, the bailer is installed at the open end of a shroud that encapsulates the motor and pump assembly. In a third preferred embodiment, the bailer is positioned in the production tubing downstream from the pump assembly. In addition to downhole applications, the bailer of the present invention can be used with surface pumping operations and in fluid transport systems. These and various other features and advantages that characterize the present invention will be apparent from a reading and review of the following detailed description, appended claims and associated drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with a preferred embodiment of the present invention,FIG. 1shows an elevational view of a pumping system100attached to production tubing102. The pumping system100and production tubing102are disposed in a wellbore104, which is drilled for the production of a fluid such as water or petroleum. As used herein, the term “petroleum” refers broadly to all mineral hydrocarbons, such as crude oil, gas and combinations of oil and gas. The production tubing102connects the pumping system100to a wellhead106located on the surface. Although the pumping system100is primarily designed to pump petroleum products, it will be understood that the present invention can also be used to move other fluids.

The pumping system100preferably includes some combination of a pump assembly108, a motor assembly110and a seal section112. The seal section112prevents the entry of well bore fluids into the motor110and shields the motor assembly110from mechanical thrust produced by the pump assembly108. The motor assembly110is provided with power from the surface by a power cable114. Although only one pump assembly108and one motor assembly110are shown, it will be understood that additional pumps and motors can be connected within the pumping system100to meet the requirements of particular applications.

Turning toFIG. 2, shown therein is a partial cutaway view of a bailer116constructed in accordance with a preferred embodiment of the present invention. The bailer116preferably includes a housing118(shown partially removed), one or more plates120, one or more bars122, an inlet124and an outlet126. The bailer116optionally includes a check valve128. Although a simple “flapper” style check valve128is depicted inFIG. 2, it will be understood that alternative valves could be employed alone or in combination with a flapper valve.

The housing118is preferably cylindrical and constructed from a rigid, corrosion-resistant material, such as steel or other suitable metal alloy. In a preferred embodiment, the portion of the housing proximate the outlet126tapers to a frustroconical end and includes vents130that permit increased flow through the bailer116. Although the housing118is preferably sized and configured to be placed inside a larger fluid conduit, the housing118can also be configured for end-to-end attachment to equipment or fluid conduits of varying size.

In the presently preferred embodiment, the bailer116includes a plurality of plates120. As shown inFIG. 2, the bailer116includes six plates120that are laterally oriented and connected at their peripheries to the inside surface132of the housing118. In this way, each of the plates120is substantially perpendicular to the direction of fluid flow through the bailer116. In an alternative embodiment, one or more of the plates120is connected to the inside surface132in a non-perpendicular relationship to the direction of fluid flow through the bailer116. Although six plates120are depicted inFIG. 2, it will be understood that the use of fewer or greater numbers of plates120may be used to accommodate the requirements of specific applications. To permit fluid flow through the bailer116, each plate120includes at least one aperture134that extends completely through the plate120.

The bailer116also preferably includes one or more elongate bars122that extend substantially along the direction of fluid flow through the bailer116. In a particularly preferred embodiment, the bars122extend through one or more plates120. It will be understood that different numbers, sizes, shapes and configurations of bars122are encompassed within the scope of the present invention. As an example, the bailer116shown inFIG. 2includes four lower bars122that extend through five lower plates120and six upper bars122that extend from an upper plate120.

In presently preferred embodiments, one or more of the plates120and bars122is constructed from a material that exhibits a magnetic field. Suitable materials include rare-earth metals, including but not limited to neodymium iron boron and samarium cobalt alloys. In a particularly preferred embodiment, the plates120and bars122are nickel-plated to prevent corrosion. The collective and separate magnetic fields provided by the plates120and bars122attract magnetically permeable solids entrained in the stream of fluid passing through the bailer116. In this way, iron sulfide particles are strained from the stream of well fluid and captured by the plates120and bars122.

If magnetic, the plates120are preferably removably connected to the inside of the housing118through magnetic attraction. In the preferred embodiment, the bars122are held in position relative to the plates120through magnetic attraction. In this way, the plates120and bars122can be easily removed from the bailer116for cleaning, separation, modification or replacement.

Turning toFIGS. 3–6, shown therein are top views of several plates120and bars122constructed in accordance with various preferred embodiments.FIG. 3depicts a plate120athrough which four large diameter bars122aand 14 small diameter bars122bpass. The plate120aalso includes 18 apertures134that permit fluid flow across the plate120. It will be understood that the determination of the size, number and configuration of bars122and apertures134on the plate120ais made after considering a number of factors, including flow characteristics, pressure drop, pump requirements and fluid properties. For example, in the preferred embodiment, the plates120and bars122are preferably configured to produce magnetic fields and fluid flow profiles that are conducive to trapping magnetically permeable solids despite opposing velocity drag, buoyancy and pressure forces. As such, the size, number and configuration of bars122and apertures134are application specific and non-limiting to the preferred embodiment.

FIGS. 4–6respectively depict a lower magnetic plate120b, an upper magnetic plate120cand a preferred configuration of the lower magnetic plate120brelative to the upper magnetic plate120c. The lower magnetic plate120bincludes four large-sized apertures134in a “cross” pattern. The upper magnetic plate120cincludes eight medium-sized apertures134in a square orientation. It is believed that offsetting the apertures134in the lower plate120bfrom the apertures134in the upper plate120cenhances the performance of the bailer116by increasing the turbulence and residence time of fluids passing through the bailer116. Although no bars122are shown inFIGS. 5–6, it will be understood that one or more bars122could be added to the plates120to adjust the performance of the bailer116.

It will be understood that the bailer116is generally configured to remove particulate solids from fluids passing through the bailer116. For the purposes of disclosing the preferred embodiment, the bailer116is described in conjunction with downhole equipment used to recover petroleum products from a subterranean formation. The bailer116is equally suited, however, for use in alternative applications or systems. For example, it may be desirable to use the bailer116in surface pumping systems, fluid transport systems and fluid storage systems.

In a first preferred application shownFIG. 7, the bailer116is used in combination with a downhole pumping system100that includes a packer136, a y-tool138and an offset intake pipe140. In this application, well fluids are drawn into an upper zone142from a lower zone144defined by the packer136through the offset intake pipe140. The bailer116is operably positioned within the offset intake pipe140to remove iron sulfide particles entrained in well fluid drawn from the lower zone144. Through use of the y-tool138, the bailer116can be easily retrieved and deployed with wireline tools lowered through the production tubing102.

In a second preferred application shown inFIG. 8, the bailer116is used in combination with an encapsulated pumping system146. The encapsulated pumping system146preferably includes a shroud148that substantially encases the pump108, motor110and seal112. The shroud148preferably includes an open end150that conducts the flow of well fluid into the pump assembly108. In this application, the bailer116is preferably located below the motor110toward the open end150of the shroud148. In this way, iron sulfide particles are trapped in the bailer116before coming in contact with the motor110, seal112or pump assembly108.

In a third preferred embodiment, the bailer116is installed in a discharge conduit152above the pump assembly108. The discharge conduit152is preferably connected between the pump assembly108and the production tubing102(not shown). Alternatively, the bailer116can be installed directly within the production tubing102, thereby obviating the need for the separate discharge conduit152. In this configuration, the bailer116removes solids, such as iron sulfide particles, before the well fluid reaches downstream components.