Universal Wireline Standoff

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to wireline logging and, more particularly, in one or more embodiments, the present invention relates to a device for improving wireline cable performance during logging operations in a variety of boreholes.

Background of the Invention

Wireline logging is a common operation in the oil industry whereby down-hole electrical tools may be conveyed on a wireline (also known as an “e-line”) to evaluate formation lithologies and fluid types in a variety of boreholes. In certain wells, there may be a risk of the wireline cable and/or logging tools becoming stuck in the open hole due to differential sticking or key-seating, for example.

Key-seating may occur when the wireline cable operates similar to a saw and cuts a groove into the borehole wall. Such cable grooves may be observed with wireline imaging tools. Once a cable groove has been cut, various sticking mechanisms may act on the wireline cable. For instance, the wireline cable may be trapped via compression. In addition, the wireline cable may be trapped in the groove by borehole stress. Moreover, mechanical binding of the wireline cable in a deep groove may occur. In instances in which the rock is permeable, differential sticking of the wireline cable may also occur. This may happen in deviated or directional wells where the wireline cable may exert sustained sideways pressure at the contact points with the borehole. Furthermore, since the logging tool diameter is generally much larger than the groove cut by the wireline cable, a key-seat may terminate normal ascent out of the borehole and potentially result in a fishing job or lost tools in hole.

Differential sticking may occur when there is an overbalance between hydrostatic and formation pressures in the borehole, the severity of which may be related to a number of issues, including: (1) the degree of overbalance and the presence of any depleted zones in the borehole; (2) the character and permeability of the formations bisected by the borehole; (3) the deviation of the borehole, since the sideways component of the tool weight adds to the sticking forces; (4) the drilling mud properties in the borehole, since the formation of mud cakes may trap logging tools and the wireline cable against the borehole wall; and (5) the geometry of the toolstring being logged on a wireline, since a long and large toolstring may present a larger cross sectional area and may result in proportionally larger sticking forces. Additionally, during wireline formation sampling, the logging tools and wireline may remain stationary over permeable zones for a long period of time, which may also increase the likelihood of differential sticking. Further, active loss zones in the wellbore may apply high sideways force and may stick the logging cable or tools.

SUMMARY

These and other needs are addressed by an embodiment of a wireline assembly having a wireline cable. The wireline assembly also has a logging tool-string and a jar. The wireline assembly further has one or more wireline standoffs located on the wireline cable above the jar. Each of the one or more wireline standoffs has a cable insert disposed between a pair of opposing assemblies. The cable insert has an anti-rotation spigot. In addition, the cable insert comprises aluminum or silicon bronze, depending on well fluid and corrosive properties.

These and other needs are addressed by an embodiment of a method of reducing cable friction above a jar of a wireline assembly. The method includes providing a wireline assembly having a wireline cable and a jar. The method also includes securing one or more wireline standoffs to the wireline cable above the jar. Each of the one or more wireline standoffs has a cable insert disposed between a pair of opposing assemblies. The cable insert has an anti-rotation spigot. In addition, the cable insert comprises silicon bronze. Moreover, the method includes conveying the wireline assembly into a borehole. Additionally, the method includes reducing a cable friction caused by the wireline cable contacting a wall of the borehole. The reducing results from the one or more wireline standoffs lowering an area of contact between the wireline cable and the wall of the borehole.

These and other needs are addressed by an embodiment of a method of assembling a wireline assembly. The method includes disposing a wireline assembly having a wireline cable and a jar into a borehole. The method also includes placing two parts of a cable insert around the wireline cable at a location above the jar. The cable insert includes an anti-rotation spigot. In addition, the cable insert comprises silicon bronze. Further, the method includes securing the two parts of the cable insert to each other. Additionally, the method includes placing a pair of opposing assemblies around the cable insert. Moreover, the method includes securing the pair of opposing assemblies to each other. The method also includes repeating the above-noted steps at a different location on the wireline cable above the jar.

An embodiment includes a wireline standoff. The wireline standoff may comprise a pair of opposing assemblies. The opposing assemblies may each comprise a half shell, a cable insert configured to be disposed in the half shell, and external fins coupled to the half shell. The wireline standoff further may comprise one or more fasteners configured to couple the opposing assemblies to one another.

Another embodiment includes a wireline assembly. The wireline assembly may comprise a wireline cable and a wireline standoff. The wireline standoff may comprise a pair of opposing assemblies, wherein each of the opposing assemblies may comprise a half shell, a cable insert disposed in the half shell, and external fins coupled to the half shell. The cable insert for each of the opposing assemblies may be coupled to the wireline cable.

Yet another embodiment may comprise a method for reducing sticking in wireline logging. The method may comprise coupling one or more wireline standoffs to a wireline cable. The one or more wireline standoffs may comprise a pair of opposing assemblies, wherein each of the opposing assemblies may comprise a half shell, a cable insert configured to be disposed in the half shell, and external fins coupled to the half shell.

The features and advantages of the present invention will be readily apparent to those skilled in the art. While numerous changes may be made by those skilled in the art, such changes are within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of the present invention and should not be used to limit or define the invention.

FIG. 1 illustrates an isometric view of an embodiment of a wireline standoff;

FIG. 2 illustrates an isometric view of an embodiment of a wireline standoff coupled to a section of wireline;

FIG. 3 illustrates an embodiment of a plurality of wireline standoffs installed on a wireline cable;

FIG. 4 illustrates a close-up view of an embodiment of a wireline standoff in relation to the borehole wall;

FIG. 5 illustrates an isometric view of a wireline standoff with one half-shell removed;

FIG. 6 illustrates an isometric view of a wireline standoff with one half-shell removed;

FIG. 7 illustrates an exploded view of an embodiment of a wireline standoff;

FIG. 8 illustrates an exploded view of an embodiment of a wireline standoff;

FIG. 9 illustrates an embodiment of a cable insert for use in a wireline standoff; and

FIG. 10 illustrates an embodiment of a wireline standoff.

DETAILED DESCRIPTION

The present invention relates to wireline logging and, more particularly, in one or more embodiments, the present invention relates to a device for improving wireline cable performance during logging operations in a variety of boreholes.

As shown in the embodiments of FIGS. 1-10, there may be several advantages to wireline standoff 2 and methods of use thereof, only some of which may be alluded to herein. Advantages include corrosion protection of cable insert 10. An additional advantage includes that cable insert 10 may be used with water-based mud. Another advantage is that wireline standoff 2 and methods of use may ameliorate the effects of differential sticking and/or key-seating of wireline cable 18 by reducing or eliminating direct contact of wireline cable 18 to borehole wall 38. In accordance with present embodiments, this may be achieved by coupling a plurality of wireline standoffs 2 onto wireline cable 18, resulting, for example, in a lower contact area per unit length of open hole, lower applied sideways pressure of wireline cable 18 against borehole wall 38, and/or lower cable drag when conveying wireline cable 18 in or out of borehole 40. Another advantage is that the use of wireline standoffs 2 may also enable more efficient use of wireline jars in the logging string, since wireline standoffs 2 may reduce the cable friction above the jars. Lower cable drag may facilitate more sufficient energy transfer from wireline cable 18 to the jar hammer, which may result in a more reliable jar firing and a more efficient re-cocking. Without wireline standoffs 2 on wireline cable 18, the high cable drags generated during the jar firing may attenuate the hammer impact velocity and may result in failure to free the logging tools. Furthermore, without wireline standoffs 2 on wireline cable 18, re-cocking the jar may be problematic due to excessive cable stiction, having just pulled wireline cable 18 into a groove when firing the jar at higher tension. The subsequent cable peel-off force may be significant and may impede re-cocking. A freely moving wireline cable 18 above the jar may be desired, especially in deviated or tortuous wells where tension transmission may be sub-optimal from the vertical well scenario. Not being able to re-cock the jar may mean the jar may not be fired again, and the wireline tools may need to be fished. The cable drag imparted to wireline cable 18 may increase the jar firing tension and may reduce jar hammer impact velocity and any or substantially any resulting impulse. In embodiments, when deciding on a location of wireline standoff 2, the location may be selected to reduce a friction caused by wireline cable 18 contacting borehole wall 38. Such location may result in a lower surface cable tension when logging up out of borehole 40, and a higher surface cable tension when logging down in borehole 40.

Referring now to FIGS. 1 and 2, a wireline standoff 2 is illustrated. In embodiments, wireline standoff 2 may comprise two opposing assemblies 4, which mate together onto wireline cable 18. A variety of different fasteners may be used to couple the two assemblies 4 to one another. By way of example, bolts, dowel pins, or any combinations thereof may be used. In an embodiment, a combination of dowel pins (illustrated, e.g., by reference number 54 on FIG. 6) and bolts 6 may be used to couple assemblies 4 to one another. In one particular embodiment, four cap head bolts 6 and four dowel pins 54 may be used for coupling assemblies 4. Dowel pins 54 may be used, for example, to resist shear forces. In an embodiment, dowel pins 54 are 4×8 mm pins.

As further illustrated in FIGS. 1 and 2, each of opposing assemblies 4 may comprise a corresponding half shell 8 which contains a cable insert 10. As shown, wireline standoff 2 contains two cable inserts 10 with each of opposing assemblies 4 containing a corresponding cable insert 10. In an embodiment, cable inserts 10 may be secured in their half shells 8 by a fastener, such as, for example, recessed cap head bolt 12. In an embodiment, contact with the exterior of wireline cable 18 may be solely with cable inserts 10 and not half shells 8. In one particular embodiment, cable inserts 10 may be configured to clamp directly onto wireline cable 18 using bolts 6. In an embodiment, cable inserts 10 may mate to form a central bore 11 through wireline standoff 2. Cable inserts 10 may be configured to slightly deform around outer wireline cable 18 armour during installation without physically damaging wireline cable 18. It is to be understood that there are a large range of cable inserts 10 available to fit wireline cable 18, taking into account any manufacturing tolerances and varying degrees of wear or distortion along the length of wireline cable 18. Therefore, for a plurality of wireline standoffs 2 installed on wireline cable 18, a range of different cable inserts 10 may be employed, for example, to ensure a fit which may not allow slippage along wireline cable 18 or damage to wireline cable 18 when coupled. Bolts 6 that may be used to couple the two assemblies 4 together may be torqued to a consistently safe limit with a calibrated torque wrench.

Half shells 8 may comprise a suitable material, such as stainless steel or other high-performance material. In an embodiment, half shells 8 may constructed from stainless steel. In addition, half shells 8 may be surface hardened (e.g., vacuum hardened or laser hard coated), in certain embodiments, for improved wear resistance during use. A wide range of shell sizes are available for installation on wireline cable 18, from an outside diameter of about 50 mm and greater, for example. In an embodiment, half shells 8 may have an outside diameter of about 75 mm. In an embodiment, the maximum external diameter of wireline standoff 2 is less than the size of the internal diameters of the overshot and drill pipe that may be used in fishing operations so that wireline standoff 2 may be safely fit inside a fishing assembly enabling the wireline cable head or tool body to be successfully engaged by the fishing overshot. In this manner, wireline cable 18 and wireline standoff 2 may then be safely pulled through the drill pipe to the surface when the cable head is released from the logging string.

Cable inserts 10 may comprise any suitable material, such as aluminum or silicon bronze. In embodiments, cable inserts 10 may comprise silicon, bronze, or any combinations thereof. In an embodiment, cable inserts 10 may comprise silicon bronze. Cable inserts 10 may comprise any suitable silicon bronze. In some embodiments, cable inserts 10 comprise high silicon bronze. An example of a suitable high silicon bronze is C65500 high silicon bronze. Embodiments include cable inserts 10 comprising high silicon bronze that comprises copper, tin, silicon, or any combinations thereof. Some embodiments include cable inserts 10 comprising high silicon bronze that comprises copper, iron, lead, manganese, nickel, silicon, zinc, or any combinations thereof. In an embodiment, high silicon bronze has at least about 97.0 wt. % copper; alternatively about 97.0 wt. % copper and about 3.0 wt. % silicon; and alternatively about 95.8 wt. % copper, about 3.3 wt. % silicon, and about 0.9 wt. % manganese; further alternatively about 91.95 wt. % to about 93.75 wt. % copper, about 0.8 wt. % iron, about 0.05 wt. % lead, about 0.50 wt. % to about 1.3 wt. % manganese, about 0.6 wt. % nickel, about 2.8 wt. % to about 3.8 wt. % silicon, and about 1.5 wt. % zinc. Without limitation, it is to be understood that silicon bronze has good corrosion properties and has similar mechanical properties to aluminum. In an embodiment, cable inserts 10 are a durable item but may be junked in the event of damage during a logging run. Furthermore, in some embodiments, cable inserts 10 may be positively secured into each of the half shells 8 by fasteners 12 (e.g., small cap head bolts) that pass through the outside of each of half shells 8 into tapped holes in cable inserts 10. In embodiments, cable inserts 10 may have no movement inside half shells 8. For example, a central spigot (see, e.g., anti-rotation spigot 64 on FIG. 7) may be included to reduce or even eliminate rotation of cable inserts 10 in half shells 8. By way of further example, a central flange (see, e.g., cable insert flange 60 on FIG. 7) on cable inserts 10 may be used to ensure little to no axial movement in half shells 8.

Wireline standoff 2 may further include a plurality of fins 14 coupled to half shells 8. Among other things, fins 14 may allow easy movement along borehole 40 and through mud cake and other debris, which may have accumulated in borehole 40 during drilling. In an embodiment, fins 14 may be arranged along the length or a portion of the length of half shells 8. In an embodiment, wireline standoff 2 may comprise twelve fins 14. In an embodiment, fins 14 may be distributed radially along the length of half shells 8. The empty space between fins 14 may allow for circulation of drilling mud inside drill pipe if wireline cable 18 and wireline standoff 2 are fished using drill pipe. In an embodiment, fins 14 have a low coefficient of friction. Fins 14 may have a smooth radial cross section to minimize the contact area with borehole wall 38 and allow for standoff rotation under the action of cable torque. It is believed that this may reduce the differential sticking force acted upon each fin 14 at the contact points with borehole wall 38 and may also allow for easy rotation of wireline standoffs 2 if wireline cable 18 rotates when it is deployed and retrieved from borehole 40. It should be noted that it is the general nature of wireline cable 18 to rotate during logging operations due to the opposing lay angles of the inner and outer armours, which may induce unequal torsional forces when tensions are applied. The design of wireline standoffs 2 may allow easy rotation of wireline cable 18 during the logging operation, avoiding, for example, the potential for damage if excessive torque was allowed to build up.

In addition, wireline standoff 2 may further include a plurality of holes 16 in half shells 8. In an embodiment, holes 16 may extend across half shells 8 for use in installation. By way of example, holes 16 may be used to connect wireline standoff 2 to a lanyard during installation to avoid dropped objects on the drill floor during installation on wireline cable 18. In an embodiment, each of half shells 8 may contain four holes 16. In embodiments, holes 16 are disposed radially about opposite ends of wireline standoff 2.

FIG. 2 illustrates a section of wireline cable 18 passing through central bore 11 (shown, e.g., on FIG. 1) of cable inserts 10 in wireline standoff 2. As illustrated, bolts 6 hold half shells 8 together while clamping cable inserts 10 onto wireline cable 18, in accordance with certain embodiments. The diameter of wireline cable 18 may vary (e.g., about 8 to about 16 mm), for example, depending on, without limitation, the logging vendor. In an embodiment, cable inserts 10 may be matched to the diameter of wireline cable 18 regardless of any variations in size or profile that might occur along the length of wireline cable 18. As previously mentioned, cable inserts 10 may comprise aluminum or silicon bronze, both may be softer than the plough steel of the wireline cable 18 armour. It is desirable to reduce the risk of damage to wireline cable 18 during installation of wireline standoff 2. By way of example, an accurate fit of cable inserts 10 on wireline cable 18 and, in certain embodiments, the controlled torque of bolts 6 during installation may reduce the risk of damage to wireline cable 18 from cable inserts 10 when bolts 6 are tightened, pulling the two half shells 8 together and cable inserts 10 into contact with wireline cable 18. A calibrated nut-runner may be employed to apply consistent torque to bolts 6.

In an embodiment, one or more of the wireline standoffs 2 may be used on a wireline cable 18. In embodiments, installation of a plurality of wireline standoffs 2 on wireline cable 18 may minimize wireline cable 18 contact over a selected zone(s) of an open-hole section. Wireline standoffs 2 may be installed on wireline cable 18, for example, to either straddle known permeable zones where differential sticking is a risk (e.g., eliminating cable contact 100%), or they may be placed at regular intervals along wireline cable 18 to minimize key-seating, taking into account, for example, the dogleg severity of borehole 40. For boreholes 40 with higher dogleg severity, the spacing between wireline standoffs 2 on wireline cable 18 may be reduced. In certain embodiments, the spacing of wireline standoffs 2 on wireline cable 18 may be from about 10 feet to more than about 175 feet, alternatively from about 10 feet to about 175 feet, and alternatively from about 25 feet to about 175 feet. Such spacing may be dependent on the requirements for the particular borehole 40 being logged. In an embodiment, the spacing of wireline standoffs 2 on wireline cable 18 may be from about 25 feet to about 175 feet. In some embodiments in casing in a pure vertical hole, the spacing of wireline standoffs 2 on wireline cable 18 may be from about 200 feet to about 250 feet.

FIGS. 3 and 4 illustrate an embodiment of a generic logging operation that includes a plurality of wireline standoffs 2 coupled to wireline cable 18. As illustrated, a plurality of wireline standoffs 2 may be clamped onto wireline cable 18. Wireline cable 18 may be, for example, stored on wireline drum 20 and spooled into the well by a winch driver and logging engineer in logging unit 22. In the illustrated embodiment, logging unit 22 is fixed to the drilling rig or platform 24, and wireline cable 18 is deployed through the derrick via two or three sheaves 26, 28 to the maximum depth of the well. Borehole 40 may have a cased-hole section 30 and an open-hole section 32. As illustrated, wireline standoffs 2 may be installed on wireline 18 in open-hole section 32. A logging tool 34 may be connected to the lower end of wireline cable 18 to take, for example, the petro-physical measurements or fluid or rock samples in open-hole section 32 of borehole 40. The number of wireline standoffs 2, and their positions on wireline cable 18 may be determined by a number of factors, including for example, the length of open-hole section 32, the location of sticky, permeable, or depleted zones, and the overall trajectory of the well, which may be deviated or directional in nature. FIG. 4 is a close-up view illustrating attachment of wireline standoff 2 to wireline cable 18 taken along circle 36. In the illustration of FIG. 4, wireline standoff 2 may be seen in relation to wireline cable 18, borehole wall 38, and borehole 40.

FIG. 5 illustrates an embodiment of one of the opposing assemblies 4. As illustrated, assembly 4 includes half shell 8 with cable insert 10 disposed therein. In an embodiment, half shell 8 includes front portion 42, rear portion 44 and middle portion 46 that interconnects front portion 42 and rear portion 44. In the illustrated embodiment, front portion 42 and rear portion 44 are each in the shape of a conic section with middle portion 46 being generally cylindrical in shape. In the illustrated embodiment, half shell 8 further includes holes 48 through which fasteners (e.g. bolts 6 shown on FIG. 1) may be inserted that secure half shells 8 to one another clamping cable inserts 10 onto wireline cable 8. Opposing assembly 4 may further contain fins 14 that extend along the length or a portion of the length thereof. As illustrated, each of fins 14 may in the shape of an arch that spans across at least a portion of middle portion 46. Accordingly, there may be a gap 50 between fins 14 and middle portion 46 with either end of fins 14 attached to half shell 8. In addition, fins 14 may be spaced around middle portion 46 so that there is a gap 52 between each fin 14.

FIG. 6 illustrates an embodiment of opposing assembly 4. In the embodiment illustrated, half shell 8 further includes dowel pins 54 sized to fit into corresponding holes in other half shell 8 (not illustrated in FIG. 6). In one particular embodiment, half shell 8 includes four dowel pins 54. In certain embodiments, dowel pins 54, in conjunction with bolts 6 (shown, e.g., on FIG. 1), may, for example, couple half shells 8 together. As previously mentioned, dowel pins 54 may assist wireline standoff 2 in resisting shear stresses.

FIGS. 7 and 8 illustrate exploded views of embodiments of wireline standoff 2. As illustrated, wireline standoff 2 includes opposing assemblies 4 that each comprises half shell 8, cable insert 10, and a plurality of fins 14. In the embodiment illustrated in FIG. 8, dowel pins 54 are included in one of half shells 2 for insertion into corresponding holes (not illustrated) in the other half shell 2. As illustrated, each of cable inserts 10 may be in the general shape of a hollow, half cylinder. Each of cable inserts 10 may have first flanged end 56 and second flanged end 58. As illustrated, first flanged end 56 and second flanged end 58 may be tapered. In an embodiment, when assembled, first flanged end 56 and second flanged end 58 each may extend beyond half shells 8 that encase at least a portion of cable inserts 10. In embodiments, cable insert flanges 60 may be disposed over at least a portion of middle portion 62 of each cable insert 10. In an embodiment, cable insert flanges 60 are integral with cable inserts 10. In an embodiment, cable insert flanges 60 are not integral with cable inserts 10. Anti-rotation spigot 64 may be formed in one or more of cable insert flanges 60. As illustrated, each of half shells 8 includes a through passageway 66 having an inner wall 68. In general, through passageway 66 in each half shell 8 is sized to receive a corresponding cable insert 10. In one embodiment, inner wall 68 of through passageway 66 in each of half shells 8 may have a cut out 70 that receives corresponding cable insert flange 60 preventing axial movement of wireline standoff 2 when installed. In addition, protrusion 72 may extend from the inner wall in cut out 70 with protrusion 72 being sized to fit into anti-rotation spigot 64 to prevent rotation of wireline standoff 2. In this manner, cable insert flanges 60 and anti-rotation spigot 64 may lock half shells 8 and cable inserts 10.

FIG. 9 illustrates an embodiment of cable insert 10. As illustrated, each cable insert 10 includes first flanged end 56, second flanged end 58, and middle portion 62. As further illustrated, cable insert 10 includes cable insert flange 60 disposed over middle portion 62 of cable insert 10. In the illustrated embodiment, cable insert flanges 60 each include anti-rotation spigot 64. In one embodiment, fasteners 74, such as small cap head screws, may be used to retain cable inserts 10 in half shells 8. As illustrated, fasteners 74 may be received by openings 76 in cable insert flange 60. For example, through holes may be formed in each half shell 8 that extend through the wall of cutout 70 in through passageway 66 for receiving fasteners 74.

FIG. 10 illustrates a cross section of an embodiment of wireline standoff 2 installed on wireline cable 18. As illustrated, wireline standoff 2 includes opposing assemblies 4 that each comprise half shell 8, cable insert 10, and a plurality of fins 14. Half shells 8 each comprise holes 16 that may be used, for example, to connect wireline standoff 2 to a lanyard during installation. In the illustrated embodiment, cable insert 10 is in contact with wireline cable 18. As further illustrated, each cable insert 10 includes first flanged end 56, second flanged end 58, and middle portion 62 with cable insert flanges 60 disposed over middle portion 62. In the illustrated embodiment, first flanged end 56 and second flanged end 58 each extend beyond half shells 8. As illustrated, cable insert flanges 60 may fit into corresponding cut outs 70 in half shells 8. In one embodiment, protrusion 72 in cutouts 70 fits into anti-rotation spigot 64 of cable insert flanges 60. As further illustrated, fasteners 74 extend through half shells 8 and into cable inserts 10.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Although individual embodiments are discussed, the invention covers all combinations of all those embodiments.