Patent Application
20200248544
This disclosure relates to methods and apparatus for use in creation of boreholes for accessing subsurface formations. The disclosure has particular application in operations where formations are subject to hydraulic fracturing.
In the oil and gas exploration and production industry bores are drilled from surface to access subsurface hydrocarbon-bearing rock formations. In certain formations, production of hydrocarbons may be enhanced by fracturing the rock to create fissures through which fluids may pass. These fissures may be created by a number of techniques, one being hydraulic fracturing, often referred to a fracking. In this technique, high pressure fluid is injected into the formation to fracture the rock. The fluid may take any appropriate form and may include acid and may carry material, known a proppant, which lodges in the fissure and maintains the fissures open when the fluid pressure is reduced.
A drilled bore may include a vertical or near vertical portion which leads into a substantially horizontal portion extending through the hydrocarbon-bearing formation. The far or distal end of the horizontal portion may be referred to as the toe of the well, while the end of the horizontal portion adjacent the vertical portion may be referred to as the heel of the well. If the formation is to be subject to hydraulic fracturing, the process is normally carried out in stages, starting at the toe and working along the well to the heel. Given that high fluid pressures are employed during the fracturing operations, and the well bore is open to the formation during the fracturing operations, operators exercise great care in ensuring that the well remains fluid-tight and the well pressure is closely monitored and controlled.
The fracturing operation may involve a suitable bottom hole assembly (BHA) mounted on a tubular support member which extends from surface. At or near surface, the support member may extend through a pressure containment apparatus such as a blowout preventer (BOP). The apparatus may provide a number of different sealing mechanisms to engage the outside of the support member and safely contain the well pressure. The high pressures utilised in fracturing operations may also result in the creation of forces which tend to push the support member out of the bore. Of course, it is necessary to translate the support member through the various seals to locate the BHA at the appropriate location in the bore and this often requires manipulation of the surface sealing arrangement and may require the provision of apparatus to accommodate the pressure forces acting on the support. Accommodating these different requirements inevitably incurs significant time and expense.
An aspect of the disclosure relates to a method of creating a well bore.
The method may include:
The pressure containment apparatus may include a blowout preventer.
An aspect of the disclosure relates to a method of creating a well bore, the method including:
The method steps may be conducted in the sequence as listed above or may be conducted in a different sequence.
While the port is open the seal on the BOP engages the jointed pipe and the jointed pipe may be translated through the apparatus. When the port is closed the formation will be isolated from the well bore. Thus, the operator is not required to manage the well pressure, which facilitates many operations; seals provided on the BOP may be retracted or otherwise open and the jointed pipe may be translated through the BOP relatively quickly.
A plurality of spaced apart valved ports may be provided on the liner and the method may be repeated for each valved port, translating the fluid delivery tool between each port location. All of the ports on the liner may be opened and closed on a single run. In other embodiments only selected ports may be opened. The ports may be opened and closed in any appropriate sequence as desired by the operator, for example, starting with the port closest to the toe of the well and working towards the port at the heel of the well.
The valved port may be opened or closed by application of pressure. The valved port may be opened or closed by mechanical force. The valved port may be normally closed, and in the absence of external influence may assume a closed configuration. The valved port may include a valve member such as an inner sleeve or barrel which is translatable to open and close the port. The valve member may be translatable towards the distal end of the liner to open the port. Of course, the valved port may include other arrangements to open and close the port.
The fluid delivery tool may include slips or other gripping arrangements. The fluid delivery tool may include a packer or other sealing arrangement. One or both of the slips and the packer may be weight-activated. The slips and the packer may be activated to engage a sleeve or barrel which is translatable to open or close the port.
The fluid delivery tool may include a fluid port and fluid pumped down through the string may exit the string through the outlet. The fluid delivery tool port may be located adjacent the open valved port in the liner.
The fracturing fluid may be of any appropriate form or composition. The fracturing fluid may carry proppant.
Displacement fluid may be delivered through the jointed pipe following the fracturing fluid. The fracturing fluid may be under displaced by the displacement fluid.
Cleaning fluid may be circulated through the well following closing the port. The cleaning fluid may be reverse circulated.
The well bore may be filled with kill weight fluid, which fluid may be brine. Alternatively, the well bore may be filled with lighter fluid, and may be underbalanced.
A cement layer surrounding the liner may be fractured by fluid delivered through the port.
The bore liner may be installed in a horizontal well bore section.
The method may further include producing fluid from the formation. The fluid may be produced through the valved port. The valve port may be configured to permit fluid to be produced through the port, or fluid may be produced through an alternative port in the liner.
An aspect of the disclosure relates to a well created in accordance with the method of the disclosure.
Another aspect of the present disclosure relates to an apparatus for creating a well bore.
The apparatus may include:
The apparatus may be provided in combination with one or more of the features described above with reference to the method of the disclosure.
The fluid delivery tool may form part of a bottom hole assembly (BHA). As used herein, the term bottom hole assembly (BHA) may refer to the lower portion of the string of jointed pipe.
The pressure control apparatus may be a blow out preventer (BOP).
Other aspects of the disclosure relate to a three position valved port and a port configured to facilitate formation of a proppant arc over the port. The various aspects of the disclosure may be used in combination, or individually.
The three position valved port may include a body defining the port and a valve member movable relative to the body, in a first position the valve member closing the port, in a second position the valve member opening the port to facilitate flow of fracturing fluid through the port, and in a third position the valve member opening the port and locating a proppant flow control member across the port. The proppant flow control member may take any appropriate configuration.
The port configured to facilitate formation of a proppant arc over the port is intended to encourage or facilitate the proppant material which aggregates at production ports, inlets or slots to form arcs spanning each port. The arcs may act as barriers for particles, thereby limiting or reducing sand production from the formation, or limiting or reducing the flow of proppant material back out of the formation. The formation of the arcs may be promoted by modifying the geometry of the ports. In one example, outer edges of the ports may be provided with a bevelled geometry.
A port configured to facilitate formation of a proppant arc may form part of a filter or screen member.
Outer and inner ports may be provided in the proppant control member. The inner ports may be smaller than the outer ports. One or both of the inner and outer ports may be configured to promote formation of proppant arcs.
These and other aspects of the present disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:
The 5½ inch (13.97 cm) liner 26 is cemented in the bore section 24; that is, the annulus 38 between the liner 26 and the wall of the horizontal section 24 is filled with cement slurry 40. Once the cement 40 has set, as illustrated in
The well 10 is now ready for fracturing and a fluid delivery tool, such as a fracturing bottom hole assembly (frac BHA) 50 is run into the well 10 on a work string 52, as illustrated in
When it is subsequently desired to produce from the surrounding formation, the barrel 176 may be moved to an intermediate position in which a ported section of the barrel 176 extends across the ports 174, as illustrated in
In particular, it is desired to prevent proppant particles from flowing back into the well. At present, the proppant supplied during the latter stages of a f racking operation may be coated with resin, which resin tends to make the proppant “sticky” and be held in the formation, or bind with other proppant particles. However, the properties of the resin may create other issues, and present the operator with environmental and safe handling complications.
The openings 104 may be sized to have a diameter a selected multiple of the diameter of the average proppant particle. If the screen openings are smaller, there is an increased likelihood that the openings will be blocked by the particles, and of the openings are larger there is an increased likelihood that the particles will pass through the openings with the produced fluid, this creating operational difficulties for the operator. Further, the openings 104 and the ports 174 are provided with bevelled edges 106, as illustrated in
There is a tendency for proppant particles to aggregate at the ports 174 and the openings 104. This provides a degree of filtering or screening, but also restricts flow through the ports 174 and openings 104. However, the beneficial effects of this aggregation may be maximized if the proppant particles can be encouraged to aggregate in an arcuate form, bridging rather than filling the ports 174 and openings 104. The provision of the bevelled edges 106 promotes the creation of arcs of proppant particles 108.
These beneficial effects may be achieved in other forms of openings, for example in slots.
The work string 52 has a diameter of 3½ inches (8.89 cm) and is mounted on 5½ inch (13.97 cm) diameter drill pipe 80. The work string 52 and drill pipe 80 are formed from multiple sections of pipe joined by threaded end connections. As such the strings 52, CGO 80 are physically robust and are well suited to pushing the BHA 50 through a long horizontal bore section. The strings 52, 80 also provide a relatively large internal bore for delivery of large volumes of fracturing fluid at high pressure, as will be described.
A seal is provided at the proximal end of the vertical well section 18, at the BOP 16.
The drill pipe 80 passes through the BOP 16 which, in the illustrated example, is located on the seabed. The BOP 16 will typically include a number of seal arrangements for engaging the outer surface of the drill pipe 80, for example an annular preventer 82 and rams 84. The annular preventer 82 will typically include a sealing element in the form of a large elastomeric doughnut that is mechanically squeezed inward to seal on the drill pipe 80. The rams 84 typically include two halves of a cover for the well that are split down the middle and define a cut-out that corresponds to the diameter of the drill pipe 80. Hydraulic rams may be operated to force the two halves of the cover together to seal the wellbore when the drill pipe 80 extends into the well 10.
Prior to or following the actuation of the packer element 160 on the frac BHA 50 to provide a lower seal one of the annular preventer 82 and rams 84 is closed around the drill pipe 80 to provide an upper seal.
Surface pumps 86 are then operated to pressurize the fluid in the well 10 to a desired level and further weight is applied to the drill pipe 80. The combination of pressure and weight generate an axial force on the BHA 50 sufficient to open the ports 174, as described above with reference to
The downward movement of the BHA 50 relative to the sleeve body 166 will continue until the distal end of the barrel 176 lands on a shoulder 90 on the body 166 below the recess 72. As the sleeve 28a is opened a pressure drop may be observed at surface. The pressure of the fluid in the well is then increased such that fluid is forced through the open sleeve 28a to break down the cement layer 40 surrounding the sleeve 28a and create fissures 92 extending from the liner 26 to the formation 22.
A predetermined volume of fracturing fluid 94 is then pumped down the drill pipe 80 and work string 52, through the ports 174 and the fissures 92 in the cement 40 and into the formation 22, as illustrated in
The fracturing fluid 94 is followed by a volume of kill weight brine 96, the volume of brine 96 pumped into the well being selected to under-displace the fracturing fluid 94 by a predetermined volume, for example 3 bbl (477 litres), as illustrated in
With the pumps 86 now turned off, the sleeve 28a is then closed by pulling up on the drill string 80 and work string 52, through the still-closed BOP annular preventer 82. The corresponding movement of the BHA 50 will pull the barrel 176 back through the sleeve body 166 to close the ports 174.
Thus, the well 10 is only open to the formation 22 for a relatively short period while the ports 174 are open. Movement of the drill string 80 during this period is achieved by stripping in and out through the annular preventer 82. Accordingly, there is no requirement for the operator to manage well pressure, which greatly simplifies operations and allows most operations to be carried out far more quickly than would be the case if it was necessary to continually manage well pressure.
The well 10 is then reverse circulated clean, as illustrated in
If desired, the annular preventer 82 may be opened once the ports 174 have been closed.
The drill pipe 80 and work string 52 are then pulled back to locate the frac BHA 50 in the second sleeve 28b, as illustrated in
This operation is repeated for each sleeve 28 until the entire length of the horizontal section has been fractured and then isolated by closing the last sleeve 28. Following the reverse circulation and cleaning of the fracturing fluid 94 used in the last fracturing operation (
The hydraulic fracturing operation as described above will typically be accomplished in a single run, without having to retrieve the BHA 50 to surface. There is also a significant time saving due to the limited time that the sleeves 28 are open and providing fluid communication with the formation 22; during most of this time the surface pumps 86 are operating and pumping high pressure into the formation 22, and the sleeves 28 are closed immediately after the pumps 86 are switched off. As a result, there is little or no need to manage well pressure.
If desired the drill pipe 80 and work string 52 may then be then be pulled out of hole (POOH).
The well has now been fracked and is ready to receive production tubing. When the operator chooses to commence production, some or all of the sleeves 28 may be opened. If considered necessary or desirable one or more of the sleeves 28 may be subsequently closed if, for example, a relatively large water fraction is being produced through the sleeve 28.
Those of skill in the art will appreciate that the examples described above are not intended to be limiting and that, for example, particular dimensions and parameters are provided only by way of example.
It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present embodiments, may be made by those skilled in the art while still remaining within the principles and scope of the disclosed embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1702025.6 | Feb 2017 | GB | national |
This application is a United States National Phase application of PCT Application No. PCT/EP2018/050480 filed Jan. 9, 2018, which claims priority to United Kingdom Application No. 1702025.6 filed Feb. 8, 2017.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/050480 | 1/9/2018 | WO | 00 |
