Patent Description:
Generally, when drilling and completing a subterranean well for the production of fluids, minerals, or gases from underground reservoirs, several types of tubulars are placed downhole as part of the drilling, exploration, and completions process. These tubulars can include casing, tubing, pipes, liners, and devices conveyed downhole by tubulars of various types. Each well is unique, so combinations of different tubulars may be lowered into a well for a multitude of purposes.

A subsurface or subterranean well is drilled through one or more formations. The formation is a body of rock or strata that contains one or more compositions. The formation is treated as a continuous body. Within the formation hydrocarbon deposits may exist. Typically a wellbore will be drilled from a surface location, placing a hole into a formation of interest. Completion equipment will be put into place, including casing, tubing, and other downhole equipment as needed. Perforating the casing and the formation with a perforating gun is a well-known method in the art for accessing hydrocarbon deposits within a formation from a wellbore.

During drilling and completing a well, and throughout the complete well's life, tools of various types may be lowered into and retrieved from the well by use of a cable or wireline. These tools are often combined into a tool string that includes multiple tools in series. A wireline can provide both mechanical support for conveying the tools in and out of the well and electronic communication between the surface and any tools in the well. A wireline that does not provide electrical communication or power between the surface and a tool is often referred to as slickline. Electrical power and communication may be provided by a wireline that ties into a cable head at the top of a tool string. The electrical signal may have to travel through several components, subs, and tools before it gets to a particular tool.

The top of a tool string may include a cable head connecting the tool string mechanically and/or electrically to the wireline. The top of a tool string often also includes a fishing neck to facilitate fishing, or retrieval of the tool string, if the wireline is compromised.

A weight bar (also known as a sinker bar or stem) is sometimes added to a tool string to facilitate conveyance of the tool string into the well. For example, the weight bar may overcome wellhead pressure and friction when introducing the tool string into the well bore. An over-the-line (OTL) weight bar is a type of weight bar with no electrical feed through and is inserted above the cable head with the wireline itself running through the inner diameter of the weight assembly. Typical OTL weight bars require that the wireline or cable be disconnected from the cable head and then reconnected to the cable head (reheading) for installation of the weight bar to the tool string. This is a potentially time consuming process that introduces opportunity for errors or malfunctions.

<CIT> provides a sinker bar for use with a hydrocarbon well apparatus connected to an operating cable through a cable head. The sinker bar includes a bar provided with a longitudinal slot. This slot is adapted to permit lateral engagement of the bar onto the cable, and to connect at one of its ends at the cable head. The bar may also be adapted to connect at its other end to a fishing head. The connection may be twist locked. The sinker bar is applicable in particular with production logging apparatus.

An object of the present invention is to enable the addition of weight to a tool string conveyed by wireline without reheading the wireline or cable.

The invention is as set out in the appended set of claims.

An embodiment may include a weight bar for use in a downhole tool string conveyed by a wireline comprising: a) a longitudinal axis substantially in line with the wireline; b) a weight section comprising: a weight section outer surface, a cable borehole along the longitudinal axis, a weight section top end distal from the tool string, a weight section bottom end proximate the tool string, a longitudinal slot extending from the cable borehole through the weight section outer surface, c) a slot closure bar fitting within the weight section longitudinal slot comprising: a slot closure bar top end, a slot closure bar bottom end, d) a slot closure bar top end retainer restricting movement of the top end of the slot closure bar relative to the weight section in at least one direction; and e) a slot closure bar bottom end retainer restricting movement of the bottom end of the slot closure bar relative to the weight section in at least one direction. In a further example embodiment the weight section further comprises: male threads on the weight section top end. In yet a further embodiment the weight section further comprises: a bottom end bore in the weight section bottom end. In a further embodiment the weight section further comprises: female threads in the bottom end bore in the weight section bottom end. In a further embodiment the weight section outer surface extends more than <NUM> degrees about the longitudinal axis between the weight section top end and the weight section bottom end. In another embodiment, the longitudinal slot extends from the weight section bottom end to the weight section top end parallel to the longitudinal axis and comprises: a first longitudinal slot side wall substantially parallel to the longitudinal axis; and a second longitudinal slot side wall substantially parallel to the longitudinal axis and the first longitudinal side wall. In another embodiment, the slot closure bar top end retainer comprises: a first longitudinal slot shoulder extending substantially orthogonal from the first longitudinal slot side wall into the longitudinal slot. In a further embodiment, the slot closure bar top end retainer further comprises: a second longitudinal slot shoulder extending substantially orthogonal from the second longitudinal slot side wall into the longitudinal slot. In another embodiment, the slot closure bar bottom end retainer comprises: a locking pin slot in the bottom end bore face and a locking pin in the slot closure bar. In a further embodiment the weight section further comprises: a bottom end bore face in the bottom end bore substantially orthogonal to the longitudinal axis. In a further embodiment the locking pin slot is in the bottom end bore face. In another embodiment, the slot closure bar fits in and substantially fills the longitudinal slot. In another embodiment, the slot closure bar comprises: a slot closure bar outer surface extending less than <NUM> degrees about the longitudinal axis from the slot closure bar top end to the slot closure bar bottom end. In another embodiment, the slot closure bar comprises: a slot closure bar inner surface engaging the first and second longitudinal slot shoulders; a first slot closure bar side wall substantially parallel to the longitudinal axis; and a second slot closure bar side wall substantially parallel to the longitudinal axis. In a further embodiment the slot closure bar retainer comprises: a locking pin extending from the first and second slot closure bar side walls substantially orthogonal to the longitudinal axis and engaging a locking pin groove in a weight section bottom bore. In another embodiment, the slot closure bar top end has a slot closure bar top end outer surface closer to the longitudinal axis than the male threads on the weight section top end, and slot closure bar bottom end has an inner surface farther from the longitudinal axis than the female threads in weight section bottom end.

Another embodiment of the invention is an apparatus for use downhole comprising: a tool string; a cable head connecting the tool string to a wireline; a fishing neck top sub attached to a top end of the tool string at a bottom of the fishing neck top sub; a cable head bottom adapter attached to the fishing neck top sub opposite the tool string; and a weight bar as defined according to the claimed invention.

For a thorough understanding of the present invention, reference is made to the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings in which reference numbers designate like or similar elements throughout the several figures of the drawing.

In the following description, certain terms have been used for brevity, clarity, and examples. No unnecessary limitations are to be implied therefrom and such terms are used for descriptive purposes only and are intended to be broadly construed. The different apparatus, systems and method steps described herein may be used alone or in combination with other apparatus, systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.

Downhole tool string components are typically assembled along a common longitudinal axis because they must typically transit a narrow cylindrical borehole. In the examples of <FIG> this longitudinal axis is represented by the wireline <NUM>.

An example set of components at the top end of a tool string is shown in <FIG> showing a wireline <NUM> that extends from the surface through a fishing neck <NUM> and a cable head bottom adapter <NUM> (shows in dashed lines to allow visibility of other components) to a cable head <NUM>. In this example, the cable head <NUM> and bottom adapter <NUM> are attached to the tool string <NUM> though fishing neck top sub <NUM>. Typically these parts are threadably attached, but may also be bolted together, attached with set screws, attached with any other attachment mechanism, or any combination of methods. In the example of <FIG>, the fishing neck <NUM> threads onto the bottom adapter <NUM> and is also secured with a cup point set screw <NUM>.

<FIG> shows the example set of components at the top end of a tool string of <FIG> with the fishing neck <NUM> detached from the bottom adapter <NUM> for attachment of a modular weight bar <NUM> to the tool string <NUM> over the wireline <NUM>. This is an example of the first step in adding a modular weight bar to a tool string without reheading the cable or wireline <NUM> into a cable head <NUM>.

An example insertion of a modular weight bar is shown in <FIG>. In this example, a weight section <NUM> is placed over the wireline <NUM> between the fishing neck <NUM> and the bottom adapter <NUM> as indicated by the arrow. This example weight section <NUM> has a longitudinal slot <NUM> leading from the weight section outer surface <NUM> to a cable borehole <NUM> from the weight section top end <NUM> to the weight section bottom end <NUM>. The cable borehole is sized to accommodate the wireline <NUM> along the longitudinal axis. The longitudinal slot <NUM> allows the weight section <NUM> to be placed over the wireline <NUM> while the wireline is still attached to other components at each end. In this example, weight section top end <NUM> has male threads <NUM> for engaging complimentary threads in fishing neck <NUM>, though these components could be attached through other mechanisms as mentioned above. In this example, weight section bottom end <NUM> has female threads <NUM> for engaging complimentary threads in bottom adapter <NUM>, though these components could be attached through other mechanisms as mentioned above. In this example, the weight section bottom end <NUM> is proximate the tool string <NUM> and the weight section top end <NUM> is distal from the tool string <NUM>; however, this direction could be reversed by appropriate modification of the attachment mechanisms of either the weight bar <NUM> and/or adjacent components. In this example, weight section bottom end <NUM> has a bottom end bore <NUM> including female threads <NUM>. In this example, there is a bottom end bore face <NUM> in the weight section bottom end bore <NUM> substantially orthogonal to the longitudinal axis and the locking pin slot <NUM> is in the bottom end bore face <NUM>.

The example of <FIG> also show a slot closure bar <NUM> for insertion into the longitudinal slot <NUM>. In this example, the slot closure bar <NUM> has a slot closure bar bottom end <NUM> proximate the tool string <NUM> and a slot closure bar top end <NUM> distal from the tool string <NUM>. This slot closure bar has a locking pin <NUM> for restricting movement the slot closure bar bottom end <NUM> relative to the weight section <NUM>. In this example, the locking pin <NUM> engages a locking pin slot <NUM> in the weight section bottom bore <NUM>. This allows the slot closure bar <NUM> to be attached to the weight section by hooking the locking pin in the weight section bottom bore <NUM> and/or locking pin slot <NUM> and rotating slot closure bar top end <NUM> toward weight section <NUM>. Slot closure bar top end <NUM> is then be captured and held against weight section <NUM> by threading fishing neck <NUM> onto weight section top end <NUM>. Weight bar <NUM> is then be attached to bottom adapter <NUM> by threading weight section bottom end <NUM> onto bottom adapter <NUM> and secured with cup point set screws <NUM> and <NUM>.

<FIG> and <FIG> show the insertion of a second weight bar <NUM>' between weight bar <NUM> and fishing neck <NUM> through the same methods and mechanisms described above with respect to the insertion and attachment of weight bar <NUM> where weight bar <NUM>' is attached to weight bar <NUM> rather than bottom adapter <NUM>.

<FIG> is a cross section view through the middle of an example weight bar <NUM>. The example of <FIG> shows the weight section <NUM> with outer surface <NUM>, cable borehole <NUM>, a first longitudinal slot side wall <NUM>, a second longitudinal slot side wall <NUM>, and first and second longitudinal slot shoulders <NUM> and <NUM> respectively. In this example, the first and second longitudinal slot side walls <NUM> and <NUM> are substantially parallel to the longitudinal axis of the weight section <NUM>. In this example, the first and second longitudinal slot shoulders <NUM> and <NUM> are substantially parallel to the longitudinal axis and orthogonal to and extending from the longitudinal slot side walls <NUM> and <NUM> into the longitudinal slot <NUM>. As shown in the example of <FIG> the longitudinal slot shoulders <NUM> and <NUM> restrict slot closure bar <NUM> from intruding into cable borehole <NUM>. In this example, the weight section outer surface <NUM> extends more than <NUM> degrees about the longitudinal axis centered in cable borehole <NUM>.

In the example of <FIG>, the slot closure bar <NUM> has an outer surface <NUM> that extends less than <NUM> degrees about the longitudinal axis of the weight bar <NUM> and weight section <NUM>. The slot closure bar of this example also has a first and second side wall <NUM> and <NUM>, respectively and an inner surface <NUM>. <FIG> shows the slot closure bar fitting within and substantially filling longitudinal slot <NUM>.

<FIG> shows an example bottom end of weight bar <NUM>, including weight section bottom end <NUM> and slot closure bar bottom end <NUM>. <FIG> shows bottom bore <NUM> in weight section bottom end <NUM> and bottom bore face <NUM> and female threads <NUM> in bottom bore <NUM>. Bottom bore face <NUM> is substantially orthogonal to the longitudinal axis. This example also shows an example locking pin slot <NUM> as a slot in bottom bore face <NUM> circumferentially about the longitudinal axis from first longitudinal slot wall <NUM> to second longitudinal slot wall <NUM>. Alternatively, locking pin slot <NUM> could be a straight slot orthogonal to the longitudinal axis or a slot in an outer wall of bottom bore <NUM> adjacent to or through female threads <NUM>. Also seen in the example of <FIG> is slot closure bar bottom end <NUM> with an inner surface <NUM> that is farther from the longitudinal axis than female threads <NUM> so as to avoid interference with complementary threads. This example also shows locking pin <NUM> in locking pin slot <NUM>, restricting the movement of slot closure bar <NUM> relative to the weight section <NUM> both radially relative to the longitudinal axis and toward the weight section top end <NUM>. Locking pin <NUM> can extend from either or both of slot closure bar side walls <NUM> and <NUM> or be integral with them.

<FIG> is a cross section of an example weight bar <NUM> through the locking pin <NUM> orthogonal to the longitudinal axis through the center of wireline <NUM>. This example shows relative positions of wireline <NUM>, weight section <NUM>, slot closure bar <NUM>, locking pin <NUM>, locking pin slot <NUM>, and first and second longitudinal slot shoulders <NUM> and <NUM>.

<FIG> is a perspective view of an example weight section <NUM> from the bottom end showing the relative positions and arrangement of weight section top end <NUM>, weight section bottom end <NUM>, weight section outer surface <NUM>, longitudinal slot <NUM>, female threads <NUM>, and male threads <NUM>.

<FIG> is a perspective cross-section (parallel to the first longitudinal slot wall <NUM> and parallel to and through the longitudinal axis) view of an example weight section <NUM> from the bottom end showing the relative positions and arrangement of weight section top end <NUM>, weight section bottom end <NUM>, weight section outer surface <NUM>, first longitudinal slot wall <NUM>, first longitudinal slot shoulder <NUM>, female threads <NUM>, and male threads <NUM>.

<FIG> is a perspective view of an example weight section <NUM> from the top end showing the relative positions and arrangement of weight section top end <NUM>, weight section bottom end <NUM>, weight section outer surface <NUM>, longitudinal slot <NUM>, female threads <NUM>, male threads <NUM>, and second longitudinal slot shoulder <NUM>.

<FIG> is a perspective cross-section (parallel to the second longitudinal slot wall <NUM> and parallel to and through the longitudinal axis) view of an example weight section <NUM> from the top end showing the relative positions and arrangement of weight section top end <NUM>, weight section bottom end <NUM>, weight section outer surface <NUM>, second longitudinal slot wall <NUM>, second longitudinal slot shoulder <NUM>, female threads <NUM>, and male threads <NUM>.

Claim 1:
A weight bar (<NUM>) for use in a downhole tool string (<NUM>) conveyed by a wireline (<NUM>) comprising:
a) a longitudinal axis substantially in line with the wireline (<NUM>);
b) a weight section (<NUM>) comprising:
a weight section outer surface (<NUM>),
a cable borehole (<NUM>) along the longitudinal axis,
a weight section top end (<NUM>) distal from the tool string (<NUM>),
a weight section bottom end (<NUM>) proximate the tool string (<NUM>),
a longitudinal slot (<NUM>) extending from the cable borehole (<NUM>) through the weight section outer surface (<NUM>),
c) a slot closure bar fitting (<NUM>) within the weight section longitudinal slot (<NUM>) comprising:
a slot closure bar top end (<NUM>),
a slot closure bar bottom end (<NUM>),
d) a slot closure bar top end retainer (<NUM>) restricting movement of the top end (<NUM>) of the slot closure bar (<NUM>) relative to the weight section (<NUM>) in at least one direction; and
e) a slot closure bar bottom end retainer (<NUM>) restricting movement of the bottom end (<NUM>) of the slot closure bar (<NUM>) relative to the weight section (<NUM>) in at least one direction.