GB2483227A

GB2483227A - Articulated wire-line hole finder

Info

Publication number: GB2483227A
Application number: GB1014351.9A
Authority: GB
Inventors: Stuart Huyton; Guy Wheater
Original assignee: GALA EARTH SCIENCES Ltd
Current assignee: GALA EARTH SCIENCES Ltd
Priority date: 2010-08-31
Filing date: 2010-08-31
Publication date: 2012-03-07
Anticipated expiration: 2030-08-31
Also published as: GB201014351D0; GB2483227B

Abstract

An articulated wire-line hole finder 1 is a modular device for a wire-line tool string to aid passage through a borehole. The hole finder comprises a roller nose 2, an articulated spring joint 4 and leaf spring centralisers 6. The roller nose comprises a mandrel 20, 15 wheels (26, fig 7) located in 5 subassemblies arranged at a 72 degree angle to the mandrel axis. The roller nose has an outer diameter approximately 60% to 80% of the borehole diameter. The articulated spring joint 4 comprises two sections (39, 47, fig 9a), a main pin (49, fig 9a) which is locked to the lower section (47, fig 9a) and a spring (54, fig 9a) between the two sections. The main pin is attached to the upper section (39, fig 9a) by a ball joint allowing articulation when the spring is compressed.

Description

Articulated \Mreline Hole Finder This invention relates to a device that aids the conveyance of wireUne logging tools down rreguar shaped and/or deviated boreholes. The arUculated wireline hole finder is connected below the wireline logging tool-string and helps navigate past obstructions in the borehole, such as ledges, washouts, and contractions which might otherwise terminate the tool-string descent to the bottom of the borehole and thereby compromise the wireline logging data acquisition objectives.

Wireline logging is a common operation in the oil industry whereby down-hole electrical tools are conveyed on wireline (also known as "e-line' in industry parlance) to evaluate formation lithologies and fluid types in a variety of boreholes. In irregular shaped boreholes, charactedzed by variations in hole size with depth, and/or in deviated boreholes, there can be problems in conveying wireline logging tools to total well depth since the bottom of the tool-string may impact upon certain features in the borehole, such as ledges, washouts, or contractions. In this situation full data acquisition from total well depth is not possible and remedial action is required, either altering the borehole conditions for more favourable descent or improving the tool-string geometry to navigate past the obstruotions; either way is costly to the well Operator.

This invention focuses on improving the wireline tool-string geometry to aid conveyance past ledges, washouts, and oontractions which may be present in irregular shaped and/or deviated boreholes. The term "hole finder is commonly used in the wireline industry for a device that connects below a logging tool-string to aid conveyance. The inclusion of the word "articulated" in the title of this invention is important since the device possesses a pivoting component which enhances performance in large ledges, washouts, or contractions that may be present in the borehole.

The articulated wireline hole finder is modular in design and features several key innovations over existing hole finders, which are often a re-arrangement of existing logging tools and/or accessories that happen to be available at the wellsite at the time of the borehole survey, i.e. they are not custom built for the purpose of effective conveyance in irregular shaped and/or deviated boreholes.

At the bottom of the articulated wireline hole finder is a roller nose with five sets of three wheeled sub-assemblies, radially phased at 72 degrees, which aid conveyance down the borehole, and across obstructions such as ledges, washouts, or contractions. Additionally, in deviated boreholes there may be solids and/or debris accumulated on the low side of the hole which the roller nose may need to drive through in order to continue descent of the well. The roller nose is selected in accordance with the size of the borehole being logged, the attached figures illustrate a roller nose or external diameter 9 34 for a 12 1⁄4" borehole, which is a common hole size in the oil industry.

Above the roller nose is a spacer sub, open to wellbore fluid, connected to an articulated spring joint, which allows the roller nose and spacer sub to be decoupled from the rest of the hole finder when activated, with approximately 12 degrees movement, in any direction, from the central axis of the hole finder. The articulated spring joint is activated when force from above, or applied tool weight, exceeds the rating of the spring in the joint. When the roller nose impacts upon a feature in the borehole, such as a ledge or contraction, it may naturally track to hole centre "finding hole" or it may momentarily come to rest if the ledge or contraction is significant. If the roller nose comes to rest the combined buoyant weight of the wireline tool-string and main body of the hole finder may be applied onto the articulated spring joint, compressing the spring and initiating a pivoting action. When the articulated spring joint is activated the roller nose experiences a horizontal component of lateral force and it moves in the direction of that force, passing the obstruction, and tracking towards hole centre. Upon finding the hole centre the roller nose is once again suspended in the borehole, without any tool weight being applied from above, and the articulated spring joint returns to its default condition of looked straight for continued descent down the borehole. The maximum lateral movement the roller nose can make, when the articulated spring joint is activated, is governed by the length of the spacer sub: Roller nose lateral limit (in) = [Spacer Sub Length (in)] * [sin(1 2)], which for a 1 m spacer sub, is 8.2'.

Above the spring joint there is a main body, open to wellbore fluid, with two S arm rotating centralisers installed. The oentralisers have a large dynamic range, effective in borehole sizes from <6" to > 20". Five arms were selected for the centralisers for improved performance, i.e. to allow effective centralisation of the hole finder without having diametrically opposing centraliser arms, which under oertain conditions can compress the centraliser to the minimum axis of the borehole, thereby reducing the effectiveness of the centraliser. The centralisers are free to rotate on the main body, thus any tool-string rotation induoed by wireline cable torque will not be applied to the centralisers. Centraliser lock rings, held by radial grub screws in the main body, limit the axial slide of each centraliser on the main body as they compress and expand with the borehole geometry. Each centraliser has two associated lock rings.

Above the main body is a crossover to the wireline logging string, which is a simple threaded connection, customised to the logging vendors' wireline tool-string connection.

The invention will now be described in detail with the aid of Figures 1-14, as summarized below. Note that "Articulated Wireline Hole Finder" implies the full assembly of aforementioned components i.e. the roller nose, spacer sub, articulated spring joint, main body, centralisers, centraliser lock rings, and crossover.

Figure 1 is view of the articulated wireline hole finder in its entirety.

Figure 2 illustrates the articulated wireline hole finder in relation to the drilling rig, logging tools, and borehole.

Figure 3 shows the articulated wireline hole finder in relation to features that may be found in irregular shaped and/or deviated boreholes, such as edges, washouts, and contractions.

Figure 3a shows a close up view of the articulated wireline hole upon impacting a ledge, and the forces applied to the spring joint and the roller nose from the buoyant tool-string weight.

Figure 3b shows a close up view of the articulated wireline hole after full actuation of the spring joint, allowing lateral and downwards movement of the roller nose to hole centre.

Figure 3c shows a close up view of the articulated wireline hole upon successful navigation past the ledge, whereby the spring joint has snapped back into its default locked position.

Figure 4 is an isometric view of the roller nose mandrel upon which the wheel sub assemblies are radially mounted.

Figure 5 is an isometric view of one of the five wheeled sub assemblies that makes up the roller nose.

Figure 6 is an isometric view of a wheel axle, and axle end retaining bolts, for fixture in the wheel retainers. The grease holes and channels for wheel lubrication, machined into the axle body, are also illustrated.

Figure 7 is an isometric view of the roller nose assembly, illustrating the five wheeled sub assemblies fixed to the mandrel.

Figure 7a is a section view through the roller nose assembly, showing the layout of the wheels and wheel retainers, and the method of fixing to the roller nose mandrel.

Figure 8 shows the spacer sub that connects the roller nose to the articulated spring joint, with female threaded connections, fluid entry and exit ports, and pilot hole for a button socket head screw.

Figure 9 is an isometric view of the articulated spring joint.

Figure 9a is a section view of the articulated spring joint showing internal components.

Figure 10 is an isometric view, including hidden lines, of the blanking plug which is utilised in the upper half of the articulated spring joint, to limit the axial movement of the main pin when activated.

Figure 11 shows the main body of the hole finder, which holds the centralisers, and is connected between the articulated spring joint upper connection and the crossover to the wirehne logging string. It shows the female threaded connections, the fluid entry and exit ports, and the mounting holes for the centraliser lock rings.

Figure 12 shows a centraliser with five leaf spring arms and sliding end mounts which allow movement over the main body when the centraliser is compressed or expanded.

Figure 12a shows a dose up of one end of the centrahser which illustrates the eaf spring arms and dvets, pivoting connections to the sliding end mounts, and locking pins.

Figure 13 shows the centrahser lock rings which are affixed to the main body with 5 grub screws to limit the axial movement of the centralisers.

Figure 14 shows the crossover, illustrating the male threaded connections for the main body and the bottom of the wireline tool-string.

The articulated wireline hole finder [1] as seen in Figure 1, comprises a series of modular components connected together via stub acme threads, which are commonly used in oilfiecd down-hole equipment. At the bottom of the articulated wireline hole finder is a roller nose [2] which comprises 5 sets of wheeled assemblies, each assembly holding 3 independent wheels. The wheeled assemblies are phased at 72 degrees around the central axis of the roller nose mandrel, facilitating low friction movement down and across the borehole. Above the roller nose [2] is a spacer sub [3] which is a tube 73 mm in diameter and of length I m to 3 m, depending on the size and condition of the borehole, the larger the washouts the longer the spacer sub required. The upper end of the spacer sub is connected to an articulated spring joint [4]. The articulated spring joint is actuated when the roller nose impacts an obstruction in the borehole, transferring buoyant tool-string weight from above and compressing the spring in the joint.

When the spring is compressed the roller nose and spacer sub may then pivot in the joint by up to 12 degrees, pushing the roller nose across and down the borehole, past the debris or obstruction(s). Above the articulated spring joint is the main body [5] which is a tube 73 mm in diameter and approximately 6 metres long. Mounted on the main body [5] are two centralisers [6] of maximum expanded diameter 30 inches, and four centraliser lock rings [7] which limit the axial movement of the centralisers on the main body [5] but maintain rotational freedom of the centralisers [6] around the main body [5]. At the top of the articulated wireline hole finder is the threaded crossover [8] to the wireline logging tool-string. Under normal running conditions, where no borehole obstructions are encountered, the articulated wireline hole tinder [1] is stiff, i.e. there is no articulation in the spring joint [4] unless the roller nose becomes immobile and then a force is applied from above.

Figure 2 shows a generic logging operation with the articulated wireline hole finder [I] deployed below the wireline logging tool-string [15] in a borehole [16]. The drilling rig, ship, or platform [12] is located above the borehole [16] and has a wireline logging unit [11], containing data acquisition equipment and associated devices mounted securely to the drilling structure. Wireline cable [9] is spooled off the drum [10] around the lower sheave [13] and upper sheave [14] into the borehole [16]. At the end of the wireline logging cable is a tool-string [15] which is used to acquire petro-physical data or samples from the borehole. Below the wireline tool-string [15] is the articulated wireline hole finder [1] which aids conveyance of the tool-string [15] past features in the borehole which might otherwise prohibit full descent to the bottom of the well. These features may include, but not be restricted to, borehole washouts [18] created by borehole instabilities during the drilling process, or ledges and contractions [1 9], which are potential obstacles to tool-string descent.

Figure 3 shows a view of the of the articulated wireline hole finder [1] when it impacts a ledge [19] in a slightly deviated borehole [16]. The centralisers [6] help maintain the position of the articulated wireline hole finder [1] towards the centre of the hole, but in this case the ledge is of a scale and geometry where the roller nose [2] has no choice but to impact upon the ledge [1 9]. Also illustrated are the borehole wall [17], a washout [18], and the spacer sub [3], articulated spring joint [4], and wireline logging tool-string [15].

Figure 3a shows a close up view of the lower part of the articulated wireline hole finder [1] when it impacts a ledge [19] in a slightly deviated borehole [16], the borehole angle from vertical is shown as theta As the roller nose [2] comes into contact with the ledge the tool-string weight from above (Mg x cos theta) may be transferred down to the spring joint [4], controlled by the wireline winch operator at surface.

The applied force compresses the spring and allows a pivoting action around the spring joint [4] and lateral movement of the roller nose [2] and spacer sub [3] towards the middle of the hole.

Figure 3b shows a close up view of the lower part of the articulated wireline hole finder [1] on a ledge [19] in a slightly deviated borehole [16], after it has been activated, i.e. the roller nose [2] and spacer sub [3] have rotated up to an angle of 12 degrees from the central axis of the articulated wireline hole finder, allowing lateral movement towards and down the centre of the hole.

Figure 3c shows a close up view of the lower part of the articulated wireline hole finder [1] after it has passed a ledge [19] in a slightly deviated borehole [16]. After the roller nose [2] has dropped past the ledge [19] its weight, plus the weight of the spacer sub [3], plus the spring force, thrusts the articulated spring joint to its default locked position, stiff and straight, where no articulation is allowed.

Figure 4 shows an isometric view of the roller nose mandrel [20] with five longitudinal slots phased at 72 degrees to hold the five wheeled sub assemblies, which are positively secured with metric cap head bolts and large dowel pins. The female threads [25] and the holes for the dowel pins [24] are clearly illustrated.

A stub acme male thread [21] allows the mandrel to be fixed to the spacer sub located above it, and a threaded pilot hole [34] is for the button socket head screw which stops the roller nose [2] from unscrewing from the spacer sub [3]. A machined flange [23] ensures a good fit between the spacer sub and the mandrel body. Four opposing holes in the mandrel body [22] allow the I itment of a C' Spanner for tightening the mandrel into the spacer sub. To save weight the mandrel is bored out from the inside, visible in Figure 7b.

Figure 5 shows an isometric view of the underside of one of the five wheeled sub assemblies that fits into the roller nose mandrel. It shows the wheel retainer [27], two metric caphead bolts [28], and two dowel pins that fit snugly into the roller nose mandrel. Also shown are three independent wheels [26] that fit into machined slots in the wheel retainer, and the axle end retaining bolts [31] with allen key holes that permit secure clamping of the axles in the wheel retainer. The axle end retaining bolts [31] are drilled out to receive a round grease probe that fills a cavity inside the axle and pushes grease around a system of channels to lubricate the wheels before running the articulated wireline hole finder [1] in the borehole.

Figure 6 shows an isometric and exploded view of one of wheel axles [30]. The axle [30] has internal female threads at both ends, into which the axle end retaining bolts [31] f, clamping securely the axle [30] to the wheel retainer. Each axle [30] has four radial holes [33] that connect the external surface of the axle to the interior cavity. Four machined channels [32] along the length of the axle [30] help the distribution of grease against the wheel and wheel retainer. The axle end retaining bolts [31] are clamped with an Allen Key and possess a round bore tc accept a grease probe, which is not illustrated in these figures.

Figure 7 shows an isometric view of the roller nose [2] in its entirety, comprising roller nose mandrel [20], wheel retainer [27], wheels [26], axle end retaining bolts [31] and Mb caphead bolts [28] which affix the wheeled sub assemblies onto the mandrel]2]. The five sets cf wheeled sub assemblies are clearly visible, with an equal phasing of 72 degrees around the central axis of the mandrel [20].

Figure 7a shows a section view of the roller nose [2], comprising roller nose mandrel [20], wheel retainer [27], wheels [26], axles [30] and Ml 0 caphead bolts [28] which affix the wheel retainers [27] onto the mandrel [2]. The two dowell pins [29] resist any shear forces on the Ml 0 caphead bolts [28] and the cavity on the inside of the mandrel terminates with a central bleed port [35] which allows wellbore fluid to drain from the roller nose and spacer sub once returned to surface. The pilot thread [34] shows where the button socket head screw is fitted to stop the spacer sub from unscrewing from the mandrel [20] and the holes [22] for the C spanner to tighten the roller nose mandrel into the spacer sub are clearly seen.

Figure 8 shows an isometric view of the spacer sub [3] in its entirety, comprising female stub acme threads [36] at either end which allow fitment onto the roller nose [2] at the bottom and the articulated spring joint [4] at the top. Also shown are a series of fluid entry and exit ports [37] in the spacer sub and pilot holes [38] for the button socket head screws which stop the spacer sub from unscrewing from its adjacent parts in the assembly.

Figure 9 shows an isometric view of the articulated spring joint [4] in its entirety, with two male stub acme threads [40] at either end which allow fitment to the spacer sub [3] at the bottom and main body [5] at the top. The flanges [43] and pilot threads [45] for connection to the main body [5] and spacer sub [3] are also shown. The spring [54] applies a compressional force between the upper and lower halves of the articulated spring joint [4], keeping the assembly stiff and impeding any articulation. Holes for the C spanner [44] allow tightening to adjacent parts of the hole finder assembly.

Figure 9a shows a section view of the articulated spring joint [4]. At the centre of the assembly is a main pin [49] which is connected to the lower half [47] of the articulated spring joint via an internal stub acme thread; male [50] and female respectively [48]. The main pin [49] is locked into the lower half [47] of the articulated spring joint with a washer [59] and two M20 nuts [60], which screw onto a male M20 thread [51] on the lower end of the main pin]49]. The upper end of the main pin [49] is not permanently fixed in the upper half [39] of the articulated spring joint [4], it possesses a tapered ball joint [53] which positively locates in a female tapered flange [46], held in it's default locked position by a spring [54] which pushes the two articulated spring joint halves [39] and [47] apart, thereby pulling the tapered ball joint [53] into the female tapered flange [46]. Upon compression of the spring [54] the main pin [49] unseats itself from the female tapered flange [46] and allows articulation of up to 12 degrees from the central axis of the articulated spring joint [4]. The upper end of the main pin [52] is hemispherical, and its axial motion is limited by the twin blanking plugs [55] which are positively located in the upper half of the spring joint [39] via a stub acme thread [56]. In both conditions, with the spring joint actuated or locked straight, the spring [54] is held in alignment with the upper and lower halves [39] and [47] respectively, by external spring flanges [42]. When the spring compression is relieved the tapered ball joint [53] pushes back into the female tapered flange [46] and the articulated spring joint [4] is locked in its default positicn.

Figure 10 shows an isometric view, including hidden lines, of the blanking plug [55] with exterior stub acme thread [56]. The Allen key hole [57] is used to tighten the blanking plug [55] into the upper half of the articulated spring joint [39]. Through the centre of the blanking plug [57] is a fluid entry port [56] which allows wellbore fluid to equalise inside the upper half of the articulated spring joint [39]. Note that the arrow highlighting the fluid entry port [58] is directed at a hidden line in the sketch.

Figure 11 shows an isometric view of the main body [5] in its entirety, comprising female stub acme threads [61] at either end which allow fitment onto the articulated spring joint [4] at the bottom and the crossover [8] at the top. Also shown are series of fluid entry and exit ports in the main body [63] and five mounting holes [62] phased at 72 degrees for the oentraliser lock rings, which limit the slide of the centraliser floating ends [68] up and down the main body [5]. The pilot holes for the button socket head screws which stop the main body from unscrewing from its adjacent parts are not shown in this figure.

Figure 12 shows an isometric view of a centraliser [6] in its entirety, comprising five leaf spring arms [64], which are connected to pivoting arm connectors [65] by four dvets [66]. The pivoting arm connectors [65] are fixed with a retaining pin [67] into the centraliser floating ends [68]. The centraliser floating ends [68] are mounted on the main body [5] with sufficient clearance to allow axial and radial movements when the centralisers [6] expand, contract, and rotate.

Figure 12a shows a close up isometric view of one end of the centraliser [6], to reveal the details of the centraliser floating ends [68]. The leaf spring arm [64] is affixed to the pivoting arm connectors [65] by four rivets [66]. The pivoting arm connectors [65] are fixed with a retaining pin [67] into the centraliser floating end [68].

Figure 13 shows an isometric view of the centraliser look ring [7] in its entirety. The purpose of the centraliser lock ring [7] is to be fixed to the main body [5] to limit the slide of the oentraliser floating ends [68] when the leaf spring arms [64] compress or expand with the borehole geometry. For a single oentraliser lock ring [7] the 5 partially threaded grub screws [70] screw into the female threads [69] and are pre-aligned with the 5 holes [62] in the main body [5]. Each centraliser [6] has two centraliser look rings [7] mounted on the main body [5] to limit the movement of the oentraliser floating ends [68] in both up and down directions.

Figure 14 shows an isometric view of the crossover [8] which fits between the upper end of the main body [5] and the wireline tool-string [15]. A male stub acme thread [72] is shown on the lower end of the crossover and an opposing male thread [75] to the logging tool-string connection is shown on the upper end. Four opposing holes [73] for the C' spanner to aid tightening are shown, along with the threaded pilot hole for the button socket head screw to ensure the crossover [7] cannot unscrew from the main body [5].

Claims

Claims: 1. The articulated wireline hole finder is a modular device which attaches to the bottom of a wireline logging tool-string to aid conveyance down irregular shaped and/or deviated boreholes which possess features such as ledges, washouts, and contractions, which might otherwise terminate full descent of the tool-string to the bottom of the borehole.
2. The articulated wireline hole finder according to claim 1 possess a low friction roller nose comprising a central mandrel that holds 15 independent wheels in 5 subassemblies, phased at 72 degrees to the central axis of the mandrel.
3. The roller nose according to claim 2 is selected for the articuLated wireline hole finder according to the borehole size being logged, from < 6!! to > 20 boreholes. The external diameter of the roller nose approdmately 60-80% of the nominal borehole diameter.4. The roller nose according to claim 2, possess 5 sub assemblies of 3 wheels which are mounted in profiled wheel retainers that bolt onto the central mandrel. The wheel spacing and geometry is designed to aid descent past obstructions and debris in the borehole and to aid low friction lateral and downwards movement in the borehole.
4. The wheel retainers according to claim 4 are profiled on their upper side with an angle of attack to avoid catching or sticking the roller nose against borehole features or casing and liner in the borehole.
5. The roller nose according to claim 2 possess 15 independent wheels mounted on axles which possess grease ports and channels to provide lubrication to the wheels. The axle end retaining bolts accept a grease probe which provides grease under pressure to fill the interior cavity of the axles and pass grease up through ports and along channels to lubricate the wheels and the internal sides of the wheel retainers.
6. The articulated wireline hole finder according to claim I possess a spacer sub which connects the roller nose assembly according to claim 2 and an articulated spring joint. The spacer sub length is selected according to the borehole size being logged, it has fluid entry and exit ports such that no wellbore pressure can be trapped in the sub upon return to surface.
7. The articulated wireline hole finder according to claim I possess an articulated spring joint which can initiate a pivoting action and push the roller nose towards hole centre, effectively transferring a lateral component of tool force from above and allowing freedom of movement in the direction of the force.
8. The articulated spring joint according to claim 7 possess two halves which are normally locked straight, connected by a main pin and a spring which is under compression.
9. The main pin in the articulated spring joint according to claim 8 is fixed rigidly in the lower half of the spring joint according to claim 7, and free to move and rotate in the upper half of the spring joint if the spring rating is exceeded by compressive force from above.
10. The articulation of the spring joint according to claim 7 is approximately 12 degrees from the central axis when fully actuated.
11. The articulated spring joint according to claim 7 is pressure compensated with fluid entry and exit ports such that no trapped pressure from wellbore fluid can be brought back to surface.
12. The articulated spring joint according to claim 7 utilises a single spring which has a rating which is selected according to the weight of the wireline tool-string above the articulated wireline hole finder.
13.. The articulated spring joint according to claim 7 utilises a single spring which is less than the external diameter of the body of the articulated wireline hole finder, so as not to induce additional rolling friction or sticking in the borehole, or casing or liner in the borehole.
14. The articulated wireline hole finder according to claim I possess a main body which connects the articulated spring joint according to claim 7 with a crossover to the wireline tool-string. The main body has fluid entry and exit ports such that no wellbore pressure can be trapped in the body upon return to surface. The main body length may be adjusted based upon borehole conditions.15. The main body according to claim 14 possess tour sets of 5 phased mounting holes for four centraliser lock rings that limit the axial travel of the two centralisers which attach to the main body.14. The articulated wireline hole finder according to claim 1 possess a pair of five arm leaf spring centralisers which can both slide and rotate on the main body according to claim 14. Fewer or more centralisers may be fitted to the main body if required.
15. The five arm leaf spring centralisers according to claim 14 are limited by axial movement on the main body by lock rings which clamp onto the main body with 5 grub screws.16. The live arm leaf spring centralisers according to claim 14 have a maximum opening diameter of 30' and a minimum compressed diameter of < 6".
16. The leaf springs of the five arm leaf spring centralisers according to claim 14 are phased at 72 degrees which maximises the centralising force, especially in deviated holes, and ensures that the centraliser cannot collapse to the minimum axis of the borehole, which could happen if an even number of arms were fitted to the centraliser.
17. The articulated wireline hole finder according to claim 1 possess a range of custom crossovers to fit a range of logging tool connections from different wireline logging vendors.