WO2004099560A1

WO2004099560A1 - Erosion resistant sand screen

Info

Publication number: WO2004099560A1
Application number: PCT/GB2004/001804
Authority: WO
Inventors: Christopher George Osborne
Original assignee: Bp Exploration Operating Company Limited
Priority date: 2003-05-07
Filing date: 2004-04-28
Publication date: 2004-11-18
Also published as: GB0310458D0

Abstract

A sand screen comprising a perforated base pipe and an erosion resistant microporous sleeve. The erosion resistant microporous material of the sleeve is preferably selected from the group consisting of microporous polymeric foams, microporous metal foams, microporous carbide monoliths, and microporous nitride monoliths.

Description

EROSION RESISTANT SAND SCREEN

EROSION RESISTANT SANDSCREEN

The present invention relates to an erosion resistant sand screen having a sleeve or cover formed from an erosion resistant microporous material.

In the course of completing an oil and/or gas well, it is common practice to run a string of casing into the well bore and then to run the production tubing inside the casing. The casing is perforated across one or more hydrocarbon bearing zones

(hereinafter "producing zones") to allow produced fluids to enter the casing bore. After the well is completed and placed in production, formation sand from unconsolidated formations may be swept into the flow path along with produced fluids. This sand is relatively fine and causes erosion of tubing, downhole equipment and surface equipment. In some completions, however, the well bore is uncased, and an open face is established across the producing zone, in particular, in horizontal well completions. Similarly, after the well is completed and placed in production, formation sand from unconsolidated formation may be swept into the flow path along with produced fluids. With either cased or uncased well bores, one or more sand screens may be installed in the flow path between the production tubing and the producing zone(s). A packer may be set above and below the sand screen to seal off the annulus in the producing zone from non-producing zones of the formation. The annulus around the screen may be packed with a relatively coarse sand or gravel which acts as a filter to reduce the amount of fine formation sand reaching the screen. Nethertheless, the remaining sand contained in the produced fluids may impinge on a screen with sufficient velocity so as to cause erosion of the screen. As the velocity of the flow of the produced fluids is increased the rate of erosion also increases. Where the fluid flow rate from one portion of the formation is greater than the fluid flow rate from another portion of the formation, the screen will erode more rapidly opposite the high flow rate portion than it will opposite the lower flow rate portion.

EP 0 999 345 relates to a tortuous path sand control screen for filtering particles out of fluid produced from a wellbore that is capable of withstanding severe downhole conditions during installation and production and that experiences low rate of erosion during gravel packing, frac packing or production. The tortuous path sand control screen comprises a base pipe and a screen wire wrapped around the base pipe such that the turns of the screen wire extend along at least a portion of the length of the base pipe and form gaps therebetween. The screen wire has a profile that reduces the velocity of particles travelling through the gaps. The profile of the screen wire channels the particles to loose energy and velocity. For example, the profile of the screen wire may channel the particles in an arcuate path. Alternatively, the profile of the screen wire may channel the particles in a multi-arcuate path.

US 5,829,522 describes a screen provided with a tubular base pipe and a filtering portion. The filtering portion is externally disposed relative to the base pipe and outwardly overlaps an opening formed radially through the base pipe. The filtering portion, thus, filters fluid flowing radially though the opening. The filtering portion may be a tubular filtering portion made of, for example, spirally wrapped and generally triangular cross-sectioned wire. The screen also includes a support material positioned between the base pipe and filtering portion and, thus helps prevent the filtering portion from being radially inwardly collapsed by radially inwardly flowing fluid. The screen also includes a coating exteriorly applied to the filtering portion. The coating may perform one or several functions including preventing erosion of the filtering portion. According to a preferred embodiment of US 5,829,522, the filtering portion is partially or completely exteriorly covered with a coating. This coating is preferably a hard and abrasion resistant material, such as flame sprayed metal, chromium, metal plasma, carbide, or other suitable material. The coating is preferably applied after the screen is otherwise completely assembled.

US 4,064,938 relates to a sand screen assembly for oil and gas wells. The assembly has a heavy-walled, erosion resistant deflector around the wire screen to deflect the stream of fluid entering the wellbore, thereby substantially reducing the erosion of the wire screen. The assembly comprises an inner section of perforated pipe, at least one layer of wire screen positioned around the pipe, and a stream deflecting means having an erosion resistant wall at least one-fourth inch thick positioned around the layer of wire screen. The stream of fluid entering the wellbore is deflected to prevent impingement on the layer of wire screen. Preferably, the outer surface of the^* stream-deflecting means is made of a resilient elastomeric material. The screen deflecting means comprises an inner sleeve position around the layer of wire screen and an outer sleeve positioned around and spaced from the inner sleeve. Both sleeves have plurality of opening, with the opening in the inner sleeve being offset from the opening in the outer sleeve such that the stream of fluid is defected and the stream of fluid entering the wellbore is prevented from directly impinging upon the layer of wire screen. The smallest dimension of the openings in the stream-deflecting means is intended to be larger than the sand particles such that substantially all of the sand particles in the particular formation pass through the openings.

There remains a need for alternative erosion resistant sand screens. According to the present invention there is provided a sand screen comprising a perforated base pipe and an erosion resistant microporous sleeve.

By erosion resistant microporous sleeve is meant that the sleeve is formed, at least in part, from a microporous material that erodes over a prolonged period of time when subjected to erosion by sand or other debris entrained in the fluids produced from a hydrocarbon bearing formation. An advantage of the sand screen of the present invention is that the erosion resistant microporous sleeve has an extended lifetime compared with conventional wire- wrapped erosion resistant sand screens.

Typically, the perforated base pipe of the sand screen has an inner diameter of 6 to 30 inches, preferably 10 to 24 inches, for example 8 to 16 inches. Preferably, the perforated base pipe is formed from metal, for example, steel, in particular, carbon steel or stainless steel.

The number, size and shape of the perforations in the wall of the base pipe are not critical to the present invention, provided that sufficient area is provided for fluid production and pipe integrity to be maintained. Typically, the perforations in the wall of the base pipe are circular or slots. Typically, the circular perforations have a diameter of from 2 mm to 2 cm. Typically, the slots have a width in the range 2 mm to 2 cm and a length in the range 2 mm to 2 cm. The base pipe may have multiple axially and/or circumferentially extending slots. The microporous material of the sleeve allows the passage of produced fluids, for example, produced hydrocarbons such as crude oil, natural gas, gas condensate and produced water therethrough to the perforated base pipe. The produced fluids then pass through the perforations of the base pipe into the interior of the base pipe. The pore size of the microporous material is selected to exclude sand particles and other debris from the interior of the base pipe. In other words, the erosion resistant microporous sleeve acts as a filter thereby preventing sand particles and other debris from passing into the interior of the sand screen.

Preferably, the average volume of produced oil flowing through 1 m² of sleeve per day in an oil well (i.e. the flux through the sleeve) is up to 50,000 barrels

(50mbd/m²/day). Preferably, the average volume of produced oil flowing through 1 m² of sleeve per day in a gas well is up to 10,000 barrels (10mbd/m²/day) and/or the average volume of produced gas passing through 1 m of the sleeve per day is up to 20,000,000 standard cubic feet (20 mmscfd/m²/day). Suitably, the erosion resistant microporous material of the sleeve is selected from the group consisting of microporous polymeric foams, microporous metal foams, microporous carbide monoliths, in particular, silicon carbide, tungsten carbide, or titanium carbide monoliths or microporous nitride monoliths, in particular, boron nitride. Suitably, the micropores of the microporous material that forms the sleeve have a diameter less than that of the sand particles that it is desired to exclude from the interior of the sand screen. Suitably, the micropores have a diameter of less than 100 microns, preferably less than 50 microns, for example 5 to 25 microns or 10 to 40 microns. Suitably, the microporous material that forms the sleeve has a volume porosity of greater than 30%, preferably greater than 50%>, more preferably, 30 to 90%>, in particular, 40 to 75%.

Suitably the sleeve has a radial thickness in the range 0.5 to 10 cm, preferably 1 to 5 cm, more preferably 2 to 4 cm.

Screen end caps maybe arranged at opposite ends of the sleeve. The end caps may be formed from metal or from a resilient material, for example, a resilient polymeric material. These screen end caps are joined to the base pipe and optionally to the ends of the sleeve. For example, where the end caps are formed of metal, the caps may be welded to the base pipe. The metal end caps may be glued to the sleeve or in the case of a sleeve formed from a microporous metal foam, welded to the metal foam. Where the end caps are formed from a polymeric material, the end caps may be glued to the base pipe and the sleeve.

Preferably, the sleeve is formed in sections, for example, tubular sections or rings. Typically, the sections have a length of from 0.1 inches to 40 feet. Preferably, the tubular sections have a length of from 1 to 40 feet, more preferably 10 to 20 feet. Preferably, the rings have a length of from 0.2 to 10 cm, preferably 0.5 to 5 cm. The sections of sleeve may be stacked around the outside of the perforated pipe. It is envisaged that the sections of sleeve may be joined together using a suitable adhesive or in the case of a microporous metal foam, by welding. Alternatively, the stacked sections of sleeve may be pressed together using a suitable biasing means. For example, each end cap may be formed of a resilient material that is urged against an end section of the sleeve by a biasing means, for example, a spring device. It is envisaged that such biasing means may be arranged at intervals along the length of the sand screen.

The sections of the sleeve may be formed from the same erosion resistant microporous material. Alternatively, the sleeve may be tailored such that sections of the sleeve are formed from microporous materials having differing erosion resistance, pore diameters or porosity. The sleeve may be secured to the wall of the perforated base pipe, for example, using a suitable adhesive, or in the case of a sleeve formed from a microporous metal foam, by welding. However, it is also envisaged that the sleeve may be removable from the perforated base pipe. Suitably, an annulus is formed between the sleeve and the perforated base pipe. Preferably, the annulus has a width of less than 1 cm, preferably less than 0.5 cm.

Where the sleeve is formed from a microporous polymeric foam, the foam may be prepared and shaped as described in US 4,242,464 and GB 2369796 which are herein incorporated by reference. Suitably, the polymeric material that forms the foam may comprise any erosion resistant polymeric material that is also resistant to the effects of hydrocarbon fluids such as crude oil and natural gas. Preferably, the polymeric material may be polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinyl chloride (PNC), a copolymer of vinyl chloride and vinylidene chloride or vinyl acetate, a butadiene-styrene copolymer, a polyester, a polyamine (for example, nylon), a polyesteramide, a polyvinyl formal, a polyvinyl alcohol, a polyacrylate (for example, polymefhylacrylate), a polystyrene or a polyurethane. Preferably, the polyethylene or polypropylene is of ultrahigh density and of high molecular weight. Suitable microporous polymeric materials are supplied by Porvair Advanced Materials.

The microporous polymeric material may be shaped into a sleeve by extruding the material through a suitable die. Alternatively, the microporous polymeric foam may be sprayed, spread or cast onto a temporary tubular support.

Where the sleeve is formed from a microporous metal foam, the metal of the foam is preferably steel, in particular, stainless steel or carbon steel. However, it is also envisaged that the microporous metal foam may comprise an aluminium alloy or a nickel alloy-

Where the microporous material forming the sleeve is a microporous metal foam, the foam may be prepared, for example, as described in US 5,943,543, US 6,085,965 or US 2002/0104405 which are herein incorporated by reference. Typically, a microporous metal foam sleeve may be prepared by extruding a tube of a polymeric foam that has been impregnated with a slurry coating of powered metal and then heating the tube to volatilize the polymer foam and sinter the metal foam. However, other standard techniques for forming and shaping a microporous metal foam may be employed. Suitable microporous metal foams are supplied by Porvair Advanced Materials.

Where the sleeve is formed from a microporous carbide material, the monolith may be a silicon carbide, boron carbide, tungsten carbide, titanium carbide, tantalum carbide or niobium carbide honeycomb structure. Where the sleeve is formed from a microporous nitride material, the monolith may be a boron nitride, silicon nitride, a transition metal nitride, or aluminium nitride honeycomb structure. Suitable, honeycomb structures are as described in US 2002/0011683 which is herein incorporated by reference. Typically, a silicon carbide monolith is prepared by shaping a plasticizable raw batch mixture comprising powdered silicon metal, crosslinking thermoset resin, powdered silicon containing filler and a water soluble thermoplastic temporary binder into a green body. The green body is then dried, heated to a temperature sufficient to carbonise the resin and sintered at a temperature sufficient to convert the green body to a porous silicon carbide sintered body. Preferably, the plasticizable raw batch mixture is extruded to form a green body in the shape of a tube or a ring. Preferably, the batch mixture includes a pore-forming filler to facilitate the formation of pores of the desired size. A honeycomb carbide structure may also be prepared as described in US 2002/0180117 which is herein incorporated by reference. It is also envisaged that the erosion resistant microporous sleeve may be formed from microporous silicon carbide monoliths supplied under the trade name LiqTech™

The erosion resistance of the sand screen may be increased by employing a sleeve having sections comprising concentrically arranged rings of an erosion resistant microporous material and of a solid material. The rings of solid material may be formed from metal or from a carbide or nitride, for example, silicon carbide, tungsten carbide or boron nitride. The radial width of the concentric ring of solid material must be different to the radial width of the concentric ring of erosion resistant microporous material. The sand screen is preferably formed from alternating first and second sections wherein the first sections comprise. an inner ring of the erosion resistant microporous material and an outer ring of solid carbide material and the second sections comprise an outer ring of the erosion resistant microporous material and an inner ring of solid carbide material. Preferably, the radial width of the concentric ring of solid carbide material is less than the radial width of the concentric ring of microporous material. By alternating the first and second sections of the sleeve there is provided a non-linear flow path for the produced fluids through the sleeve with the ring of solid material in each section of the sleeve acting as a barrier to the produced fluids thereby forcing the produced fluid to pass to the ring of erosion resistant microporous material of the adjacent section(s) of the sleeve.

In a further embodiment of the present invention, there is provided an erosion resistant sleeve for a conventional sand screen, for example, a wire-wrapped sand screen, wherein the sleeve comprises a plurality of erosion resistant solid rings arranged in a stack around the outside of the conventional sand screen, the rings having grooves or ribs on the upper and lower surfaces. When the rings are arranged in a stack, tortuous transverse flow channels are formed between the rings for transporting produced fluids through the sleeve to the sand screen. Without wishing to be bound by any theory it is believed that at least part of the energy of the sand particles entrained in the produced fluids is dissipated by impingement on the walls of the tortuous transverse flow channels thereby reducing the rate of erosion of the conventional sand screen. Preferably, the rings are formed from a carbide or nitride, for example, silicon carbide or tungsten carbide.

The sand screen of the present invention may be used in cased vertical wells, uncased wells, deviated wells or horizontal wells. Typically, disposed within the casing of a cased vertical well and extending from the wellhead is production tubing. A seal is provided between the production tubing and the casing to prevent the flow of produced fluids therebetween. During production, the produced fluids enter the wellbore through perforations of the casing and flow into the production tubing to the wellhead. As part of the final bottom hole assembly, the sand screen of the present invention may be included within the production tubing to filter particles out of the produced fluids. The screen may be interconnected to the production tubing by tubular end connectors.

The present invention will now be illustrated by reference to Figures 1 to 4. Illustrated in Figure 1 is a prior art sand control screen 1 operatively positioned in a subterranean wellbore 2 adjacent a formation 3 which has been lined with protective casing 4. The casing 4 has been perforated to permit fluid flow between the formation 3 and the wellbore 2. Screen 1 is suspended from production tubing 5 which extends to the wellhead.

During production of fluids, represented by arrows 6, from the formation 3, the fluids enter the screen 1 and are transported to the wellhead through the production tubing 5. Any sand in the fluid 6 should be filtered out by the screen 1 and not permitted to flow into the production tubing 5. The screen 1 is gradually eroded over . time as the fluid 6 flows through the screen. Higher rates of flow of the fluid 6 through the screen 1 cause faster erosion of the screen. If the rate of flow of the fluid 6 through a particular perforation 7 is greater than the rate of flow of the fluid through the other perforations, as is frequently the case in gas wells, a portion 8 of the screen 1 opposite the high flow rate perforation 7 will erode faster than other portions of the screen 1. When the portion 8 of the screen 1 has eroded enough to permit sand and other debris to enter the tubing 5, the entire screen 1 must be replaced at great cost to the well operator, even though most of the screen is not yet eroded.

Figure 2 is a view of a sand screen 1 according to the present invention comprising a perforated pipe 2, and a sleeve comprising stacked sections 3 of an erosion resistant microporous sleeve, and an end cap 4. The sections of sleeve are omitted from the upper part of the sand screen 1 to illustrate the perforated pipe 2.

Figure 3 is a transverse cross-sectional view of the sand screen 10 in the plane A-A' showing the perforated pipe 11, a section 12 of the sleeve and an annulus 14 between the section of sleeve 12 and the perforated pipe 11.

Figure 4 is a longitudinal cross-sectional view of a sand screen 20 according to the present invention comprising a perforated base pipe 21 and stacked alternating first 22 and second 23 sections of a sleeve with an annulus 24 being formed between the sleeve and the perforated base pipe 21. End caps 25 are provided at the ends of the sand screen. The first sections of sleeve 22 comprise an inner concentric ring 26 formed from a solid material and an outer concentric ring 27 formed from an erosion resistant microporous material. The second sections of sleeve comprise an inner concentric ring formed from an erosion resistant microporous material 28 and an outer concentric ring formed from a solid material 29. The sleeve has a non-linear flow path for the produced fluids indicated by arrows 30.

Claims

1. A sand screen comprising a perforated base pipe and an erosion resistant microporous sleeve.

2. A sandscreen as claimed in claim 1 wherein the perforated base pipe has an inner diameter of 6 to 30 inches.

3. A sandscreen as claimed in claims 1 or 2 wherein the perforated base pipe is formed from metal.

4. A sandscreen as claimed in any one of the preceding claims wherein the perforations in the wall of the base pipe are circular perforations having a diameter of from 2 mm to 2 cm and/or slots having a width in the range 2 mm to 2 cm and a length in the range 2 mm to 2 cm.

5. A sandscreen as claimed in any one of the preceding claims wherein the erosion resistant microporous material of the sleeve is selected from the group consisting of microporous polymeric foams, microporous metal foams, microporous carbide monoliths, and microporous nitride monoliths.

6. A sandscreen as claimed in any one of the preceding claims wherein the micropores of the microporous material that forms the sleeve have a diameter of less than 100 microns, preferably less than 50 microns.

7. A sandscreen as claimed in claim 6 wherein the micropores of the microporous material that forms the sleeve have a diameter in the range 5 to 25 microns.

8. A sandscreen as claimed in any on of the preceding claims wherein the microporous material that forms the sleeve has a volume porosity of greater than 30%, preferably in the range 30 to 90%.

9. A sandscreen as claimed in any one of the preceding claims wherein the sleeve has a radial thickness in the range 0.5 to 10 cm, preferably 1 to 5 cm.

10. A sandscreen as claimed in any one of the preceding claims wherein screen end caps are arranged at opposite ends of the sleeve and are joined to the base pipe and optionally to the ends of the sleeve.

11. A sandscreen as claimed in claim 10 wherein the screen end caps are formed from a metal or from a resilient material.

12. A sandscreen as claimed in any one of the preceding claims wherein the sleeve is formed from tubular sections or rings.

13. A sandscreen as claimed in claim 12 wherein the tubular sections have a length of from 1 to 40 feet, preferably 10 to 20 feet.

14. A sandscreen as claimed in claim 12 wherein the rings have a length of from 0.2 to 10 cm, preferably 0.5 to 5 cm.

15. A sandscreen as claimed in any one of claimsl2 to 14 wherein the sections of sleeve are stacked around the outside of the perforated pipe.

16. A sandscreen as claimed in claim 15 wherein the sections of sleeve are joined together using an adhesive.

17. A sandscreen as claimed in claim 15 wherein the sections of sleeve are pressed together using a biasing means.

18. A sandscreen as claimed in any one of the preceding claims wherein an annulus is formed between the sleeve and the perforated base pipe having a width of less than 1 cm.

19. A sandscreen as claimed in any one of the preceding claims wherein the sleeve comprises alternating first and second sections wherein the first sections comprise an inner ring of an erosion resistant microporous material and an outer ring of a solid metal, carbide or nitride material and the second sections comprise an outer ring of the erosion resistant microporous material and an inner ring of solid metal, carbide or nitride material.

20. An erosion resistant sleeve for a conventional sand screen wherein the sleeve comprises a plurality of erosion resistant solid rings arranged in a stack around the outside of the conventional sand screen, the rings having grooves or ribs on the upper and lower surfaces thereof.