CA2132458A1 - Multi- port oilfield liner connector - Google Patents

Abstract

In the oil and gas industry , wellbores are now commonly drilled horizontally through the oil or gas bearing reservoir rock . It is common to equip ("complete") the producing section with a special pipe (called a liner) which facilitates maintenance or enhancement of productive capacity . Since the producing section is so long (100 m to 2000 m) for horizontal wells in comparison to vertical wells (1 m to 20 m) , the conventional liner completion designs , which were primarily designed for vertical wells ,are often prohibitively expensive for horizontal wells. In response to this expense, many horizontal wells are left uncompleted ("open hole") or are completed with a simplified liner design , which compromises well performance . This invention is a low cost ported liner design which enables the following: Retrievability, reuse , clean outs of produced sand , hydraulic jetting of multiple simultaneous "perforations" , abrasive jetting of multiple simultaneous "perforations"
limited entry stimulation or chemical soaks underbalanced operations , low torque and drag installation .
The invention is essentially a specialized hole located in the liner couplings .

Description

SPECIFICATION
This invention relates to holes or ports installed in threaded couplings ( which join lengths of pipe together for installation in an oil , gas or water well) in a fashion which enables easy installation , retrieval , reuse , debris removal, or reservoir damage removal in an oil, gas or water well at a low cost . The invention is particularly suited to long horizontal wellbores .
/0 After an oil , gas or water well is drilled , The wellbore must be equipped and stimulated in order to initiate well production ; this process is referred to as "completing" the well . Since the year 1985 it has become very common for the oil and gas industry to drill horizontal wellbores for the production or injection of oil or gas or water from subterranean rock reservoirs.
The length of the horizontal wellbore may be as much as 2000 m but is more commonly 300 m to 1000 m . There are a wide variety of methods of "completing" these 2 0 wellbores but they fall into four (4) categories namely with openhole , cemented , slotted liner and combination isolated /slotted installations. The objectives of a well completion are commonly to maximize flow rate and to maximize recovery factor ( ie the fractional recovery of the oil or gas from the porous reservoir rock ) . Maximum flow rate is usually achieved by removing any blockages or restrictions in 213245~
-the reservoir ("formation damage") or in the wellbore Recovery factor is maximized by creating uniform flow patterns ("sweep efficiency") within the reservoir Uniform flow patterns often require selective enhancement of flow from low flow regions and/or restriction of flow from selected high flow regions.
The four categories of well completions are further discussed per the following:

Open hole . Open hole completions are simply drilled /~ into the reservoir rock and left open for production fluids to enter or for injection . The advantage of this method is the minimal cost and the significant flexibility to install an optimized liner after more well performance data is analyze. The first disadvantage is the possibility of rock collapse into the open bore which may block flow and pre empt the running of an optimized liner at a later date . The second disadvantage is that there is no compensation for the reservoir blockages ("formation damage") that 2 0 mainly occur during the drilling process . The primary damage is created to a depth of 25mm to 100 mm into the borehole wall , while secondary damage may occur to a depth of 2 m . The third disadvantage is poor "sweep efficiency" since flow will follow the paths of least resistance rather than follow a uniform pattern .

2I32~8 ._ This invention overcomes the first disadvantage by placing a liner (specially equipped pipe) inside the wellbore . This invention overcomes the second disavantage by enabling penetration of formation damage by hydraulic jet impact or by uniform placement of reactive chemicals. This invention overcomes the third disadvantage by enabling selective hydraulic penetration or selective chemical placement as required to equalize flow paths.

/0 Cemented . Cemented completions achieve maximum wellbore stability and selectivity . They have the disadvantage of creating the most severe "formation damage" and the methods used to overcome the damage are extremely costly when applied to long horizontal wellbores . Cemented completions may use any of the devices and methods normally employed in the industry for vertical wells but at a very high cost due to the great length of horizontal wells - the cost is often prohibitive . Such methods include shaped explosive 2 0 charge perforations , sand hydraulic jet perforations , bullet perforations , hydraulic jet perforations propellant driven fractures , hydraulic fracture placement of sand or similar proppants , hydraulic fracture placement of acid , injection or soaking of acid into the rock pores , injection or soaking of chemical into rock pores . Fluid treatments may be 21~2~58 selectively focused with special equipment or may be spread out with particulate diverting agents or chemicals . This invention has the advantage of providing good stability , significant selectivity and the capability to overcome "formation damage" at the lowest cost .
Slotted liner . Slotted liner completions generally have the advantage of low cost and wellbore stability .
They also are the only type of completion to control /0 sand production from unconsolidated sands by using specially sized slots . They have the disadvantage of enabling few methods to effectively overcome "formation damage" and have poor selectivity with respect to "sweep efficiency" . Slotted liners are fabricated from multiple sections of normal pipe which consists of 9-15 m long sections of blank pipe which are held together by threaded couplings which are lOcm - 30 cm in length . Normally the multiple sections of pipe are shipped to a fabricator who creates a large number of 2 ~ slots or holes on the long sections of pipe . The fabricated liner is then shipped to the wellsite. In this invention only the threaded couplings are specially fabricated t e.g. by drilling "ports" in the coupling) , thereby achieving savings in transportation and handling costs . This invention also has the advantage that since the long sections of pipe are untouched , the pipe sections can be re used by 2l~2~s8 replacing the couplings.
Slotted liner completions may use many of the devices and methods normally employed in the industry for vertical wells but at a very high cost due to the great length of horizontal wells -the cost is often prohibitive . Such methods include axial slots radial slots , drilled holes, holes with insert screens , spaced wire wrap on slotted or drilled pipe aggregate filters over slotted pipe , aluminum plugs JO which shear off or dissolve in acid to expose holes .
This invention resembles a slotted liner completion more than the other completion types . This invention has no provision for sand control. This invention overcomes the "formation damage" disadvantage and the "sweep efficiency " disadvantage as discussed under "openhole" completions .

Combination isolated/slotted . Combination isolated/slotted completions can be assembled with a wide variety of accessories . These provide some 2 ~ degree of selectivity to aid in "sweep efficiency"
however the cost is relatively high and the accessories are complicated and subject to malfunction. Aside from this , they have the same advantages and disadvantages of "slotted liner" completions .
This invention has the advantage of providing good stability , significant selectivity and the capability to overcome "formation damage" at the lowest cost .
This invention has no moving parts and no special tools need be placed in the assembly therefore there is minimum risk of failure .
Combination isolate / slotted liner completions may use many devices and methods normally employed in the industry for vertical wells but at a very high cost due to the great length of horizontal wells - the cost is /0 often prohibitive . Such methods include all of the methods discussed under "slotted liners" but may include devices which seal off the concentric space between the pipe and the cylindrical borehole. They may include sliding sleeves or rotating sleeves which expose ports across specific sections of the borehole .

An ideal completion method should include:
- ability to accomodate equipment to penetrate beyond "formation damage" ; and - ability to restrict or enhance flow from specific 7 0 sections of the well bore in order to enhance hydrocarbon recovery with good "sweep efficiency" ; and - simplicity of construction to minimize malfunction ; and - ease of placement in a well bore or retrieval of same ; and - minimal cost to procure ; and 2132~58 -- minimal cost to deliver ; and - high flexibility to accomodate various operational or monitoring devices.
Existing devices provide or partially provide only 2 to 4 of these 7 listed functions .
I have found that these functions can all be provided by constructing a liner with special ports drilled ( or otherwise placed ) in the couplings which are used to screw together lengths of liner pipe . The ¦O liner is then installed in a horizontal wellbore Production from the wellbore may enter through the ports or through the concentric annular space between the liner and the wellbore wall. The production profile may be enhanced by injecting ,into the liner, chemicals ( optionally solids laden fluids ) which exit via the ports ; thereby focusing jets of chemical against the wellbore wall.

The invention consists of a ported coupling which holds together lengths of pipe which are run into a drilled oil wellbore for the purpose of enhancing and maintaining oil production . The ported coupling may be constructed on any coupling used in a "threaded and coupled" style of piping. Such couplings are most commonly constructed from steel but may be alternately constructed from metal alloys or plastic . The most common coupling style used in the oil industry are API

213245~

(American Petroleum Institute) 8 Round threaded casing and API 8 round EUE ( External Upset End ) threaded tubing . Port(s) are created by drilling a hole , with a drill or other metal removing device , at midpoint along the length of the coupling . Locating the port at the midpoint of the coupling location has the least effect on the tensile and torque integrity of the coupling . For maximizing inflow , several ports of maximum 25 mm diameter may be drilled on each coupling . For focusing fluid jets to penetrate the wellbore wall , the port profile is more effective if the inlet of the port has a smooth profile . Such nozzles may have an inner diameter as small as 6 mm or smaller .
Such nozzles may be separately fabricated and installed in a ported coupling by threading or welding or otherwise locking in place. For focusing of solids laden fluids to deeper penetrate the wellbore wall , such nozzles may be comprised of hardened steel or tungsten carbide or ceramic or other abrasion resistant materials or coatings . For selective placement of fluid along the wellbore , the diameter and frequency of the ports may be varied . The ports may have exit orientations which are other than perpendicular to the wellbore wall for a variety of reasons . The pipe body may be equipped with devices which centralize the coupling in the wellbore and /or reduce friction for rotating or axially moving the liner assembly .

In drawings which illustrate embodiments of the invention, Figure 1 is a perspective view of one embodiment , Figure 2 is front view of this embodiment , Figure 3 is an axial cross section of the embodiment of Figure 2 along the line X-X' .
Figure 4 is a radial cross-section view of the embodiment of Figure 2 along the line Y-Y'.
Figure S is an end view of Figure 2 as indicated by /0 the line Z-Z' .
Figure 6 is a view of a vertical section of the earth through a horizontal well , in which the liner installation is shown externally .
Figure 7 is an enlarged view of a vertical section through a horizontal well in an inflow condition.
Figure 8 is an enlarged view of a vertical section through a horizontal well in a well stimulation condition .

Referring to the drawings ,the embodiment of the Z G invention shown in Figure 1 is a ported coupling 10 comprised of a conventional threaded pipe coupling 12 in which a port 14 has been pierced through the side of the coupling. Figure 1 also shows truncated portions of the liner 16 and 17 (liner is a common term describing the pipe or tubing or casing used in this type of 2132~58 application) which the coupling is used to join .
The port 14 shown in this embodiment could be created by drilling through the side of the coupling .
Alternately the port could be created by other metal piercing devices and procedures . The location of the coupling must be at the midpoint along the length of the coupling as shown in Figure 2. The midpoint is chosen because it is the area where a port will not interfere with the connecting of the pipe and where fluid passage ~0 through the port will not be interrupted by the presence of the threaded pipe. Examination of Figure 3 shows that this is the case . The area in which the port is to be located is commonly referred to , in industry standard pipe , as the "J-area" dimension 18 as shown in Figure 3.
The configuration of the port may be a simple radial drill hole as shown in Figure 3 and Figure 4.
Alternately the port may be heat treated or coated to give it better wear characteristics. Alternately the ZO port may be tapered or otherwise streamlined to give the optimum flow characteristics . Alternately a nozzle comprised of specialized material may be threaded or welded or otherwise secured in place to enhance the performance of the port . The orientation of the port axis need not be exactly 90 degrees to the pipe axis.
The bore dimension of the port , for most industry standard couplings ,should be a maximum diameter of 25 JO

2l32~8 mm . For most industry applications the port's bore diameter would be larger than 3 mm.
There may be more than 1 port per coupling . In some installations , it is not necessary or desirable to have a port on every coupling .
Most industry liner installations comprise steel pipe , this invention is not limited to steel pipe.
Most industry installations comprise steel couplings , however this invention is not limited to steel coupling.
Figure 6 shows a view of a vertical section of the earth through a horizontal well , in which the liner installation 20 is shown externally . The oil or gas reservoir rock is indicated as 22 and the cylindrical (approximately) borehole wall is indicated as 24 . The space between the liner installation and the borehole wall is called the annulus 26. The large pipe ,referred to as casing 28 , is cemented in place and is usually continuous to surface. Most of the overlying earth and well equipment are not detailed in these figures .
Figure 7 shows a vertical section through a horizontal well in an inflow condition. Depending on the reservoir , fluids may flow to surface via the production tubing 30 or may require the assistance of a downhole pump 32 . Reservoir production may flow toward surface or to the pump 32 via two paths , the first path is through the inside of the liner via flow path 34 the second flow path is via the annulus flow path 36 .

21324~8 Figure 8 shows a vertical section through a horizontal well in a well stimulation condition .
Treatment fluids are pumped down (flow path 38) the production tubing 30 and the fluids exit the ports 14 in the couplings and impact the wellbore wall 24. Excess fluids return to surface via the annulus 26. To achieve such stimulation ,it may be necessary to block off the end of the assembly . Such blocking can be achieved in this embodiment by incorporating a ball seat in the end /0 of the assembly and pumping a seating ball 40 prior to initiation of the injection. Erosion and chemical reactions with the treatment chemicals and the rock will enhance reservoir flow characteristics .

In summary this invention can be deployed by placing specialized holes (ports) in the couplings of a production tubing or production liner and installing the assembly in a horizontal wellbore . Production of reservoir flow will take place through these ports . If necessary , stimulation chemicals can be injected so as 2 0 to exit via the ports and impact the reservoir rock in an effective manner . The assembly can easily be modified to meet the needs of a specific horizontal wellbore.

Although only a single embodiment of the present - 2l32~58 invention has been described with illustrations , the present invention is not limited to the features of this embodiment, but includes all variations and modifications within the scope of the claims .

Claims (10)

1. A ported coupling , several of which , hold together lengths of pipe which are run into a wellbore drilled into the earth for the purpose of production or injection of oil or gas or water or any combination thereof .

2. A coupling as claimed in 1 , comprising:
ports placed near halfway along the length of the coupling .

3. A coupling as claimed in 1 , comprising ports which are created by drills or other metal removing devices and which penetrate the wall of the coupling in a more or less radial orientation .

4. A coupling as claimed in 1 , comprising ports equipped with nozzles or check valves or acid soluble plugs or shear off hollow lugs .

5. A coupling as claimed in 1 or 2 or 3 or 4, comprising ports with profiles or inserts to enhance focusing of exit fluid or to enhance dispersion of exit fluid .

6. A coupling as claimed in 1 , 2, 3, 4 or 5 comprising ports coated with or constructed from abrasion resistant materials such as tungsten carbide or ceramic .

7. A ported coupling assembly , as claimed in 1 ,2,3,4,5 or 6 , which is used for the removal of debris from an oil or gas well .

8. A ported coupling assembly , as claimed in 1 2,3,4,5 or 6 , which is used to place cement in a wellbore.

9. A ported coupling assembly as claimed in 1,2,3,4,5,6,7 and 8 : which is used in horizontal wellbores .

10. A wellbore pipe assembly comprising cylindrical subs which function in the same manner as devices claimed in 1 , 2 ,3,4,5,6,7,8, and 9 but are merely added to a piping assembly rather than by means of modifying the coupling to do the same function .