CIRCULATION SUB

Abstract

A circulation sub tool includes a tool body with a bore extending therethrough, a sleeve movably disposed within the bore and having a sleeve bore extending therethrough, a collet disposed within the sleeve bore, and an activation dart configured to fit within the sleeve bore. The activation dart includes a dart body, a seal disposed on an outer surface of the dart body, and a channel recessed into the outer surface of the dart body.

Description

BACKGROUND

This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

In performing various downhole operations, situations arise that require fluids to be selectively directed to a bottom hole assembly or to an annulus of a well bore surrounding a tool string. Downhole tools having valve arrangements have been used to selectively direct fluids to components of the tool string or the well bore as desired.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

A circulation sub tool includes a tool body with a bore extending therethrough, a sleeve movably disposed within the bore and having a sleeve bore extending therethrough, a collet disposed within the sleeve bore, and an activation dart configured to fit within the sleeve bore. The activation dart includes a dart body, a seal disposed on an outer surface of the dart body, and a channel recessed into the outer surface of the dart body.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a sectional view of a circulation sub tool according to aspects of the disclosure;

FIG. 2 is a partial sectional view of the circulation sub tool of FIG. 1 with an activation dart landed according to aspects of the disclosure;

FIG. 3 is a partial sectional view of the circulation sub tool of FIG. 1 in a sleeve open configuration according to aspects of the disclosure;

FIG. 4 is a partial sectional view of the circulation sub tool of FIG. 1 with a deactivation dart landed according to aspects of the disclosure;

FIG. 5A is a side view of an activation dart according to aspects of the disclosure;

FIG. 5B is a sectional view of an activation dart according to aspects of the disclosure;

FIG. 6 is a detail view of an activation dart according to aspects of the disclosure;

FIG. 7A is a side view of a deactivation dart according to aspects of the disclosure;

FIG. 7B is a sectional view of a deactivation dart according to aspects of the disclosure

FIG. 8 is a sectional view of the circulation sub tool of FIG. 1 with a split-flow activation dart landed according to aspects of the disclosure;

FIG. 9A is a side view of a split-flow activation dart according to aspects of the disclosure; and

FIG. 9B is a sectional view of a split-flow activation dart according to aspects of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

As used herein, the terms connect, connection, connected, in connection with, and connecting may be used to mean in direct connection with or in connection with via one or more elements. Similarly, the terms couple, coupling, coupled, coupled together, and coupled with may be used to mean directly coupled together or coupled together via one or more elements. Terms such as up, down, top and bottom and other like terms indicating relative positions to a given point or element are may be utilized to more clearly describe some elements. Commonly, these terms relate to a reference point such as the surface from which drilling operations are initiated.

A circulation sub tool allows lost circulation material, cement, acids or other fluids to be pumped into the well bore without these materials passing through tools connected to a distal end of the drill string. Preventing these materials from passing through the tools is desirable as these materials can damage or clog up the tools. These materials are diverted from the distal end of the drill string by pumping an activation dart down into the string and landing the activation dart in the circulation sub tool. The landed activation dart blocks passage of these materials below the circulation sub tool. With the interior diameter of the circulation sub tool blocked by the activation dart, a sleeve within the circulation sub tool is shifted due to fluid pressure that builds upstream of the activation dart. The fluid pressure causes a sleeve to shift within the circulation sub tool, which opens one or more passages formed through a wall of the circulation sub tool.

After the circulation sub tool has served its purpose, a deactivation dart is pumped down to the circulation sub tool to allow for drilling operations to continue. The deactivation dart displaces the activation dart from the sleeve to permit fluids to once again flow through the circulation sub tool to the distal end of the drill string. In another aspect, the circulation sub tool can also be configured to allow for split flow between the well bore and the drill string by using an activation dart that includes an axial flow path with a nozzle. The size of the nozzle can be varied/selected to alter the split ratio of fluid flow between the well bore and the drill string. Split flow of the fluid allows for fluid to still be supplied to a bottom hole assembly while at the same time directing some fluid into the annulus of the wellbore for clean out.

FIG. 1 is a sectional view of a circulation sub tool 100 according to aspects of the disclosure. An upper end of tool 100 attaches to a distal end of a drill string and permits fluid to selectively flow through a bore 102 of tool 100 through one or more ports 104 formed through a wall of tool 100, or a combination of bore 102 and the one or more ports 104. In various aspects, a bottom hole assembly (e.g., a mud motor, bit, bit sub, and the like) is attached to a lower end of tool 100.

Tool 100 includes a tool body 106 and a dart catcher body 108 that is coupled thereto. As illustrated in FIG. 1, tool body 106 and dart catcher body 108 are separate pieces that are joined together. In some aspects, tool body 106 and dart catcher body 108 may be a unitary piece. Bore 102 extends through tool body 106 and dart catcher body 108 and permits fluid to flow from the drill string through tool 100. Ports 104 may be selectively fluidly coupled to bore 102 to permit some or all of the fluids passing through bore 102 to flow out of tool 100 and into an annulus surrounding tool 100.

Tool body 106 includes a sleeve 110 that is situated within bore 102. Sleeve 110 includes a sleeve bore 112 that permits fluid to pass axially therethrough and at least one sleeve port 114 that permits fluid to flow radially from sleeve bore 112. As shown in FIG. 1, sleeve 110 includes an upper portion 110′ and a lower portion 110″. In various aspects, upper and lower portions 110′ and 110″ thread together during assembly of tool 100. Sleeve 110 is configured to translate axially within bore 102 between a sleeve closed position (pictured in FIG. 1) and a sleeve open position (pictured in FIG. 3). In the sleeve closed position, sleeve ports 114 and ports 104 are not aligned and fluid cannot flow from bore 102 to the annulus surrounding tool 100 via ports 104. In the sleeve open position, sleeve 110 axially translates within bore 102 so that ports 104 and sleeve ports 114 are aligned to permit fluid to flow from bore 102 to the annulus surrounding tool 100 via ports 104 and sleeve ports 114.

Tool body 106 includes a spring 116 that biases sleeve 110 in the sleeve closed position. Sleeve 110 includes a spring guide 117 around which spring 116 is situated. Spring guide 117 is a portion of a length of sleeve 110 and prevents spring 116 from buckling. A first end of spring 116 bears against a shoulder of tool body 106 and a second end of spring 116 bears against a shoulder of sleeve 110. The operation of spring 116 will be discussed in more detail below.

Tool body 106 includes guide pins 118 that extend from a wall of tool body 106 into slots 119 formed into sleeve 110. Guide pins 118 and slots 119 keep sleeve 110 radially aligned within tool body 106 so that sleeve ports 114 and ports 104 are radially aligned when sleeve 110 is in the open position. Sleeve 110 includes a collet 120 with fingers 121. The operation of collet 120 will be discussed in more detail below.

Dart catcher body 108 includes a dart catcher cage 122. Cage 122 is configured to receive darts that have been displaced from sleeve 110. Cage 122 includes openings 128 that extend along a length of cage 122 and openings 130 that are located in a lower portion of cage 122. Openings 128, 130 permit fluid passing into cage 122 to pass through cage 122 and around any darts that are landed in cage 122. Cage 122 has a length sufficient to catch a plurality of darts so that tool 100 may be cycled between the sleeve open and sleeve closed positions without need to pull tool 100 from the wellbore. Fluid passing through and around cage 122 continues down through bore 102 and into the bottom hole assembly.

FIG. 2 is a partial sectional view of tool 100 of FIG. 1 in the sleeve closed position with activation dart 124 landed in collet 120 according to aspects of the disclosure. During one aspect of operation of tool 100, fluid flows through the drill string, through bore 102 of tool 100 (when sleeve ports 114 are blocked as in FIG. 1), and into a bottom hole assembly attached to tool 100. In order to configure tool 100 in the open sleeve configuration, activation dart 124 is inserted into the drill string. Activation dart 124 travels down the drill string until it is caught by collet 120. As shown in FIG. 2, activation dart 124 has landed in collet 120. With activation dart 124 positioned in collet 120, fluid flows through the drill string and into tool 100, but the fluid is prevented from flowing any farther down string by the presence of activation dart 124.

FIG. 3 is a partial sectional view of tool 100 of FIG. 1 in the sleeve open configuration according to aspects of the disclosure. With activation dart 124 landed in collet 120, fluid located upstream of activation dart 124 exerts a pressure upon activation dart 124. When pressure exerted upon activation dart 124 exceeds the bias of spring 116, sleeve 110 is translated axially downward. Sleeve 110 translates downward until a lower end of sleeve 110 abuts a shoulder 132 that is formed on an inside of tool body 106. Once sleeve 110 has landed upon shoulder 132, sleeve ports 114 and ports 104 are aligned and fluid is free to flow out of tool 100 and into the annulus surrounding tool 100 (i.e., the annulus between the wellbore and tool 100). Fluid will continue to flow into the annulus as long as the pressure being exerted upon activation dart 124 is sufficient to overcome the bias of spring 116. To stop the flow of fluid into the annulus, pressure applied to the fluid being communicated to the drill string is reduced (e.g., fluid is no longer pumped into the drill string). Once the pressure applied by the fluid to activation dart 124 is sufficiently reduced, the bias of spring 116 overcomes the pressure being exerted on activation dart 124 and sleeve 110 axially translates upward and sleeve ports 114 and ports 104 cease to be aligned to prevent flow of fluid into the annulus.

FIG. 4 is a partial sectional view of tool 100 of FIG. 1 with deactivation dart 126 landed on activation dart 124 according to aspects of the disclosure. After operating tool 100 in the sleeve open configuration by landing activation dart 124 in collet 120, it may be desirable to configure tool 100 in the closed sleeve configuration to permit fluid to flow through tool 100 and into the bottom hole assembly. To adjust tool 100 into the closed sleeve configuration, deactivation dart 126 is inserted into the drill string and allowed to travel down the drill string until landing upon activation dart 124. Activation dart 124 is configured with a length that positions deactivation dart 126 so as to block the openings of sleeve ports 114 when deactivation dart 126 is landed on activation dart 124. With sleeve ports 114 blocked, pressure from the fluid in the drill string rises. Eventually the pressure rises to a threshold that overcomes the grip of fingers 121 upon activation dart 124, and activation dart 124 is pushed free from collet 120. Separation of activation dart 124 from collet 120 is discussed in more detail below. Deactivation dart 126 is dimensioned and configured so that deactivation dart 126 is not captured by collet 120 (e.g., deactivation dart 126 has a smooth surface that fingers 121 cannot interlock with) and passes therethrough once activation dart 124 pushes free from collet 120. The interaction between activation dart 124, deactivation dart 126, and collet 120 is discussed in more detail below. Activation dart 124 and deactivation dart 126 then descend from collet 120 and are captured in cage 122.

Referring to FIG. 1, a lower end of cage 122 includes a catcher that is dimensioned so that activation dart 124 cannot pass through the lower end of cage 122 and is retained therein. A length of cage 122 is sufficient to capture and retain multiple pairs of activation and deactivations darts so that tool 100 may be cycled through multiple sleeve closed/sleeve open configurations without the need to remove tool 100 from the well bore.

FIGS. 5A and 5B are side and sectional views, respectively, of activation dart 124 according to aspects of the disclosure. Activation dart 124 includes a dart body 136 with a seal 138. Seal 138 is retained on dart body 136 via a retainer 140. Retainer 140 may be secured to dart body 136 via a retaining ring or may be threaded onto dart body 136. Seal 138 helps create a fluid-tight seal between activation dart 124 and sleeve 110. Seal 138 may be made of ertalyte or similar materials. One or more O-rings 142 may be positioned between seal 138 and dart body 136 to improve the seal between activation dart 124 and sleeve 110. Dart body 136 includes a channel 144 that is recessed into dart body 136. Channel 144 includes a lip 146 that helps retain activation dart 124 in the event of unexpected downhole pressure. Channel 144 includes an angled face that complements an angled face of fingers 121.

FIG. 6 is a detail view of activation dart 124 landed in collet 120 according to aspects of the disclosure. Each finger 121 includes a tab 123 that extends radially inward. Tab 123 includes an angled face 125 that helps spread fingers 121 apart as activation dart 124 slides through collet 120. An angled face 148 of activation dart 124 has a complementary angle to that of angled face 125. Angled face 148 has a frustoconical shape. Angled face 148 is angled relative to a face that is perpendicular to an axis passing through dart body 136. Tab 123 engages channel 144 to retain activation dart 124. The angle of faces 125, 148 is oriented so that a downward force upon the dart body (i.e., force from upstream) tends open fingers 121 to allow activation dart 124 to pass through collet 120. The angle of faces 125, 148 is chosen to be able to retain activation dart 124 when tool 100 is operating in the sleeve open configuration (i.e., to hold onto activation dart 124 while fluid is flowing through sleeve ports 114 and ports 104) and to release activation dart 124 when deactivation dart 126 is landed on top of activation dart 124. The angle of the faces is chosen to withstand fluid pressure during normal operation, and to open at higher fluid pressures. In some aspects, the angle of faces 125, 148 may be between >90 degrees and <180 degrees. Lip 146 of activation dart 124 abuts a face 127 of tab 123. Face 127 is perpendicular to a central axis passing through dart body 136. Lip 146 secures activation dart 124 in collet 120 in the event of unexpected pressure downhole.

FIGS. 7A and 7B are side and sectional views, respectively, of deactivation dart 126 according to aspects of the disclosure. Deactivation dart 126 includes a dart body 150 with a seal 152 attached thereto. Seal 152 creates a seal between deactivation dart 126 and sleeve 110 to allow fluid pressure to build upstream of deactivation dart 126 to dislodge activation dart 124 from collet 120 when converting tool 100 from the sleeve open configuration to the sleeve closed configuration. A length of deactivation dart 126 is chosen so that seal 152 is positioned upstream of sleeve ports 114 (e.g., see FIG. 4). Seal 152 may be secured to dart body 150 via a retaining ring or may be threaded onto dart body 136. One or more O-rings 154 may be positioned between seal 152 and dart body 150 to improve the seal between deactivation dart 126 and sleeve 110.

FIG. 8 is a sectional view of tool 100 of FIG. 1 with a split-flow activation dart 160 landed according to aspects of the disclosure. In the split flow configuration shown in FIG. 8, split-flow activation dart 160 permits fluid to flow into the annulus surrounding tool 100 and through bore 102 and into the bottom hole assembly. Split-flow activation dart 160 works in a similar manner as activation dart 124 and is discussed in more detail with respect to FIGS. 9A and 9B. FIG. 8 illustrates an alternative configuration for guide pins 118 and slots 119 in which guide pins 118 and slots 119 are located in a lower portion of sleeve 110.

FIGS. 9A and 9B are side and sectional views, respectively, of split-flow activation dart 160 according to aspects of the disclosure. Split-flow activation dart 160 includes a dart body 162 with a seal 164 and a nozzle 166. Split-flow activation dart also includes a bore 168 that permits fluid to flow through split-flow activation dart 160. Seal 164 is retained on dart body 162 via a retainer 170. Retainer 170 may be secured to dart body 162 via a retaining ring or may be threaded onto dart body 162. Seal 164 may be made of ertalyte or similar materials. One or more O-rings 172 may be positioned between seal 164 and dart body 162 to improve the seal between split-flow activation dart 160 and sleeve 110. Dart body 136 includes a channel 176 with a lip 178 that interact with collet 120 in a similar manner as channel 144 with and lip 146 of activation dart 124.

Nozzle 166 sits within bore 168 and includes a beveled opening 180 and a bore 182. Bore 182 has a smaller diameter than bore 168. One or more O-rings 174 may be positioned between nozzle 166 and dart body 162 to improve the seal between split-flow activation dart 160 and nozzle 166. Nozzle 166 is designed to be removable from split-flow activation dart 160 so that the performance of split-flow activation dart 160 can be tuned based upon design requirements. For example, the dimensions of nozzle 166 can be altered to create more or less flow through bore 102 relative to the flow through sleeve ports 114/ports 104. In some aspects, multiple nozzles 166, each having different diameters, may be used in connection with tool 100 to achieve the desired split-flow of fluid through tool 100.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the disclosure. Those skilled in the art should appreciate that they may readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the disclosure. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.

Claims

1. A circulation sub tool comprising:

a tool body with a bore extending therethrough;

a sleeve movably disposed within the bore and having a sleeve bore extending therethrough;

a collet disposed within the sleeve bore; and

an activation dart configured to fit within the sleeve bore and comprising: a dart body; a seal disposed on an outer surface of the dart body; and a channel recessed into the outer surface of the dart body.

2. The circulation sub tool of claim 1, further comprising:

a dart catcher body coupled to the tool body and comprising a dart catcher bore extending therethrough; and

a cage disposed within the dart catcher body.

3. The circulation sub tool of claim 2, wherein the cage comprises openings that permit fluid to pass through the circulation sub tool when the activation dart is positioned in the cage.

4. The circulation sub tool of claim 2, wherein the cage has a length long enough to hold the activation dart, a second activation dart, and two deactivation darts.

5. The circulation sub tool of claim 1, further comprising a spring that biases the sleeve in a first position.

6. The circulation sub tool of claim 1, further comprising:

a port formed through a wall of the tool body; and

a sleeve port formed through a wall of the sleeve.

7. The circulation sub tool of claim 6, wherein when the sleeve is in a sleeve open position, the port formed through the wall of the tool body and the sleeve port formed through the wall of the sleeve are aligned.

8. The circulation sub tool of claim 6, wherein when the sleeve is in a sleeve closed position, the port formed through the wall of the tool body and the sleeve port formed through the wall of the sleeve are not aligned.

9. The circulation sub tool of claim 6, further comprising a deactivation dart comprising:

a dart body; and

a seal disposed on an outer surface of the dart body,

wherein, when the activation dart is seated in the collet, the deactivation dart has a length that positions a portion of the dart body to block the sleeve port when the deactivation dart is resting on the activation dart.

10. The circulation sub tool of claim 1, wherein the collet comprises a finger having a tab disposed on a distal end of the finger.

11. The circulation sub tool of claim 10, wherein:

the tab includes an angled face that contacts an angled face of the activation dart when the activation dart is seated in the collet; and

the angle of the angled faces tends to move the finger radially outward when a deactivation dart is landed on the activation dart.

12. The circulation sub tool of claim 10, wherein the tab extends into a channel formed into a surface of the activation dart when the activation dart is seated in the collet.

13. The circulation sub tool of claim 1, wherein the channel comprises:

a first face that is frustoconical in shape; and

a second face that is perpendicular to a central axis of the dart body.

14. The circulation sub tool of claim 1, wherein the activation dart comprises a bore that extends through the dart body.

15. The circulation sub tool of claim 14, wherein the activation dart comprises a nozzle that is disposed within the bore that extends through the dart body.

16. The circulation sub tool of claim 15, wherein the bore that extends through the dart body has a first portion with a first diameter and a second portion with a second diameter.

17. The circulation sub tool of claim 16, wherein the nozzle is disposed in the second portion.

18. The circulation sub tool of claim 15, wherein the nozzle comprises a beveled opening.

19. The circulation sub tool of claim 1, wherein:

the tool body comprises a guide pin that extends into a slot of the sleeve; and

the guide pin prevents rotational movement between the sleeve and the tool body.

20. The circulation sub tool of claim 1, wherein the channel includes a first face that tends to push fingers of the collet open when the activation dart moves in a downhole direction and a second face that prevents the activation dart from moving uphole.