WO2024028734A1

WO2024028734A1 - Remote well stimulation method

Info

Publication number: WO2024028734A1
Application number: PCT/IB2023/057733
Authority: WO
Inventors: Nathan Wolford; Kevin Knight; David Sheetz
Original assignee: C-Innovation, LLC
Priority date: 2022-08-01
Filing date: 2023-07-29
Publication date: 2024-02-08

Abstract

A method for stimulation of a subsea oil and gas well is provided, comprising the deploying a tree cap on a subsea well using a remotely operated vehicle (ROV), wherein the tree cap includes one or more fluid receptacles; deploying a rigless stimulation tool (RST) in a predetermined location on the sea floor away from the well and other subsea production system infrastructure; deploying at least one flexible well service jumper (WSJ) conduit having a first end connector and a second end connector from a well stimulation vessel (WSV), where the WSJ conduit includes a plurality of attached buoyant members sufficient to enable movement by the ROV under an overhead obstacle, such as a mobile offshore drilling unit or platform; and delivering a well stimulation fluid via the fluid stimulation conduits through the RST and via the WSJ conduit to the well.

Description

Remote Well Stimulation Method

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to devices and methods used in oil and gas well stimulation operations, and more particularly to such devices and methods which enable well stimulation in wells for which vertical access to wells directly beneath the intervention vessel is either impossible or impractical. This could be due to a platform or mobile offshore drilling unit (MODU) above the subsea wells.

2. Prior Art

Well stimulation of offshore oil and gas wells often requires vessels that perform a well intervention on the well to increase production by improving the flow of hydrocarbons from the reservoir to the well bore, such as by hydraulic fracturing, acidizing, and sand control treatments. These activities are often assisted by subsea remotely operated vehicles (ROV’s) to perform a variety of tasks at great depths. The well stimulation vessel (WSV), sometimes referred to as an intervention vessel, typically includes high-rate, high-pressure pumping abilities, mixers, proppant storage tanks, and related equipment to enable preparation and pumping of a wide range of additives and blends for stimulation operations.

In the case of wells located directly beneath an existing platform, it is either impossible or impractical to provide well stimulation in a conventional manner. Therefore, the applicant has developed a system and method for providing well stimulation to wells for which vertical access cannot be accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements. While the preferred embodiment depicted in the figures shows the deployment of a single well service jumper (WSJ) 9, multiple WSJ conduits 9 may be necessary or desirable depending on the well conditions prior to stimulation.

shows an overhead view of an offshore production platform or mobile offshore drilling unit (MODU) (the “platform”) and subsea well system and manifold having one or more wells directly beneath the platform, and further shows a rigless stimulation tool (RST), also referred to as an intervention manifold, and other devices, including ROV’s and an intervention vessel or WSV, necessary to provide well stimulation in accordance with the present invention.

Figs. 2 and 3 show elevation views of the deployment and routing of one or more well service jumper (WSJ) conduits connected between the tree cap on a well and the rigless service tool (RST) or intervention manifold on the sea floor.

shows the routing and connection of a plurality of conduits in catenary form extending from the intervention vessel or WSV operating in a designated safe operating zone from the platform and connected to the RST or intervention manifold.

shows an overhead view of the platform and the routing of one or more WSJ conduits between the tree cap and the RST, as well as the routing of the stimulation conduits between the RST and the WSV.

DETAILED DESCRIPTION OF THE INVENTION

Before the subject invention is further described, it is to be understood that the invention is not limited to the particular embodiments of the invention described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

In this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs.

Turning now to the figures, a remote well stimulation method is described. With reference to Figs. 1 and 5, a well service vessel (WSV) 6 is positioned adjacent to an offshore oil and gas platform 1. The WSV 6 includes one or more remotely operated vehicles (ROV’s) 8 which can be launched via the moonpool of the vessel or via crane over the side of the vessel and used to perform various tasks as explained below. For the purposes of this invention, one or more well heads 11 having well trees 2 are located at the sea floor beneath the platform 1 and connected to a common manifold 30 by subsea well jumpers 4 for extraction of hydrocarbons via subsea production flowlines 4 as is well understood. Depending on the location of each well 11, some of the wells 11 may not be readily accessible for well stimulation activities.

With reference to the figures, and particularly Figs. 2 and 3, an ROV 8 launched from the WSV 6 is used to deploy an intervention tree cap 10 on a subsea well head tree 2, wherein the tree cap 10 includes one or more fluid receptacles for connection to conduits which deliver well stimulation fluids to the well 11. Because wells 11 which are directly beneath the platform 1 must be accessed from a remote location in such instances, a rigless stimulation tool (RST) or intervention manifold 5 is deployed via vessel crane in a predetermined location on the sea floor away from the well 11 and outside the overhead platform or vessel footprint as well as any minimum stand-off distances from critical subsea elements, e.g., production equipment, facility mooring lines, and related components. The water column 7 directly below the platform 1 is also shown in Figs. 2 and 3. The RST 5 is typically supported on the sea floor by a mudmat or designated suction pile strategically installed for this express purpose.

Next, at least one flexible well service jumper (WSJ) conduit 9 having a first end connector and a second end connector is lowered from the WSV 6 into the sea via a crane on the WSV 6. The WSJ conduit 9 includes a plurality of attached buoyant members 13, 15 sufficient to reduce the weight of the WSJ conduit 9 in the water during installation as well as to relieve the weight of the WSJ conduit 9 which may be laid over other subsea assets 14 as shown in . As further noted below, the method described herein may employ more than one WSJ conduit 9 depending on the needs of the stimulation scenario.

The ROV 8 is then used to pull the first end connector of the WSJ conduit 9 under the platform to a location near the tree cap 10 and temporarily secured to the subsea tree structure. The crane on the WSV 6 is then used to lower the WSJ conduit 9 along a predetermined route away from the tree cap 10 toward the RST 5. The route for the WSJ conduit 9 is determined by agreement between the well stimulation service company and the operator to avoid contact or entanglement with other subsea assets in the area. Consequently, the length of the WSJ conduit 9 will vary depending on the specific needs and conditions on the sea floor and the distance of the RST 5 from the well 11. For the purposes of avoiding contact or entanglement of the WSJ conduit 9 with other subsea assets 14, and as noted above, the WSJ conduit 9 is supported by a plurality of buoyant members 13, 15 as needed along its length, as shown in .

Once the WSJ conduit 9 is properly positioned along the predetermined route, the ROV 8 is used to connect the second end connector of the WSJ conduit 9 to the RST 5 via a high-flow hot stab connection 12 to enable a fluidic connection between the tree cap 10 and the RST 5. The ROV 8 includes an onboard supply of a dyed hydrate inhibitor fluid, typically a monoethylene glycol (MEG) fluid, and the ROV 8 then delivers the fluid through the WSJ conduit 9 to displace water within the WSJ conduit 9. The first end connector of the WSJ conduit 9 is then connected to the tree cap 10 via a high-flow hot stab connections 12, and preliminary subsea pressure testing of the system can commence.

Now that the WSJ conduit 9 is fully connected between the RST 5 and the tree cap 10 of the well 11, the WSV 6 is then repositioned in a designated safe operating zone (SOZ) outside of a minimum acceptable operating distance 20 from the platform 1, typically at least 300 feet from the platform 1, for deployment of the necessary fluid conduits 19 as shown in to deliver well stimulation fluids from the WSV 6 to the RST 5. While the WSV 6 is positioned in the SOZ, fluid conduits 19 are deployed from the WSV 6 via spools located on the WSV 6, wherein each of the conduits 19 has a first end connector and a second end connector. The first end connector of each of the conduits 19 is fluidically connected to a coiled tubing line 16 on the WSV 6, and the coiled tubing lines 6 are fluidically connected to the well stimulation fluid sources. Preferably, the conduits 19 are connected to the coiled tubing lines 16 via passive breakaway connectors, often referred to in the industry as mid-line weak link (MLWL) connectors 18. Each of the coiled tubing lines 16 include clump weights 17, and the conduits 19 are lowered to a position where the clump weights 17 are about 50-100 feet above the sea floor, and preferably about 100 feet above the sea floor. During deployment, the conduits 19 are suspended from a pendant cable from the WSV 6, and the pendant cable is disconnected when the conduits 19 are in a substantially vertical orientation.

Finally, an ROV 8 is then used to connect the second end connectors of the conduits 19 to the RST 5 to enable a fluidic connection with the RST 5. Conduits 19 are shown in in their catenary installed form when fully connected between the RST 5 and the WSV 6. Now that the conduits 19 are connected to the RST 5, the well stimulation fluids can be delivered via the conduits 19 through the RST 5 and via the WSJ conduit 9 to the well 11.

As will be understood, the embodiments of Figs. 1-5 may be modified to suit a wide range of operational environments and combinations of features, including but not limited to the lengths of the WSJ conduit 9 and the conduits 19. Also, it may desirable or necessary to deploy multiple WSJ conduits 9 fluidically connected between the tree cap 10 and the RST 5 for delivering different or additional well stimulation fluids depending on the pre-stimulation conditions of the well 11. Likewise, various alternatives in the steps required to deploy the RST 5, the WSJ conduit 9, and the stimulation fluid conduits 19, as well as achieving remote well stimulation using such components, are within the scope of the invention described and claimed herein.

All references cited in this specification are herein incorporated by reference as though each reference was specifically and individually indicated to be incorporated by reference. The citation of any reference is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such reference by virtue of prior invention.

It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.

Claims

A method for stimulation of a subsea oil and gas well, comprising:
(a) deploying a tree cap on a subsea well using a remotely operated vehicle (ROV), wherein the tree cap includes one or more fluid receptacles;
(b) deploying a rigless stimulation tool (RST) in a predetermined location on the sea floor away from the well and other subsea production system infrastructure;
(c) deploying at least one flexible well service jumper (WSJ) conduit having a first end connector and a second end connector from a well stimulation vessel (WSV), where the WSJ conduit includes a plurality of attached buoyant members sufficient to enable movement by the ROV under an overhead obstacle, such as a mobile offshore drilling unit (MODU) or platform;
(d) operating the ROV to move the first end connector of the WSJ conduit to a first location near the tree cap and temporarily securing the securing the first end connector to the tree frame sufficient to enable flushing of the WSJ conduit with a hydrate inhibitor fluid;
(e) operating a crane on the WSV to lower the WSJ conduit along a predetermined route away from the tree cap toward the RST;
(f) operating the ROV to connect the second end connector of the WSJ conduit to the RST to enable a fluidic connection;
(g) operating the ROV having an onboard supply of the hydrate inhibitor fluid and delivering the fluid through the WSJ conduit to displace water within the WSJ conduit;
(h) connecting the first end of the WSJ conduit to the tree cap;
(i) positioning the WSV in a safe overboarding zone (SOZ);
(j) while the WSV is positioned in a SOZ, deploying one or more fluid stimulation conduits from the WSV, wherein each of the fluid stimulation conduits has a first end connector and a second end connector, and wherein the first end connector is fluidically connected to a coiled tubing line on the WSV;
(k) operating the ROV to connect the second end connectors of the fluid stimulation conduits to the RST to enable a fluidic connection; and
(l) delivering a well stimulation fluid via the fluid stimulation conduits through the RST and via the WSJ conduit to the well.
The method of claim 1, wherein the RST is mounted on a mudmat or suction pile.
The method of claim 1, wherein during deployment of the WSJ conduit between the well and the RST by the ROV, the WSJ conduit is supported by one or more buoyant members.
The method of claim 1, wherein the fluid stimulation conduits are connected to the coiled tubing lines via passive breakaway, such as mid line weak link (MLWL), connectors.
The method of claim 1, wherein each of the coiled tubing lines include clump weights, and wherein the fluid stimulation conduits are lowered to a position where the clump weights are about 50-100 feet above the sea floor.
The method of claim 1, wherein the fluid stimulation conduits are deployed via a pendant cable from the WSV, and wherein the pendant cable is disconnected when the fluid stimulation conduits are in a substantially vertical orientation.
The method of claim 1, wherein the fluid stimulation conduits are deployed via a crane positioned on the WSV, and wherein the crane is disconnected when the fluid stimulation conduits are in a substantially vertical orientation.
The method of claim 1, wherein the WSJ conduit is supported by a plurality of buoyant members as required to avoid contact with or relieve weight on other subsea assets.
The method of claim 1, wherein the ROV is operated to position and install the WSJ conduit under the MODU or platform.
The method of claim 1, wherein multiple WSJ conduits are connected between the tree cap and the RST.