SYSTEM AND METHOD FOR CONSTRUCTION AND COMPLETION OF PRODUCTION AND INJECTION WELLS IN THE PRE-SALT FIELDS

Abstract

The present invention refers to a system and method for construction and completion of wells in the pre-salt production and injection fields. The application of the present invention allows a reduction in well construction time of approximately seven days considering the drilling and completion of the well. The system comprises string accessories, cement, AMB, production string, casings, HFIV, fluid, wellhead system, subsea equipment, DHSV and packer. The method aims at reducing one well phase, resulting in three drilling phases, with the running in of only two casings and the completion in an open well with part of the same exposed to the saline formation, herein called 2R-PAC.

Claims

1. A system for construction and completion of production and injection wells in pre-salt fields, the system comprising: a subsea equipment, a wellhead system, a drilling fluid or a completion fluid, a cement, casings, a production string, string accessories, DHSV, HFIV, Packer and AMB.

2. The system according to claim 1, wherein the casing has a length between 30 (76.2 cm) and 36 (91.44 cm).

3. The system according to claim 1, wherein the cement is configured to cement the casing.

4. The system according to claim 1, wherein the drilling fluid is configured to be exchanged for the completion fluid when drilling steps are completed.

5. The system according to claim 1, wherein the DHSV is closed at an end of the construction.

6. A method for construction and completion of production and injection wells in pre-salt fields, wherein the method comprises three drilling phases with the running in of two casings, the method comprising: drilling with a drill bit or a drill bit and a reamer subsequently running in a conductive casing having a length between 30 (76.2 cm) and 36 (91.44 cm); drilling with a water drill bit until close to the base of a saline formation, maintaining a minimum distance above a reservoir; drilling to a final programmed depth of a well, drilling the remainder of the saline formation; and completing the well.

7. The method according to claim 6, wherein seawater and a drilling fluid are used in the step of drilling with a drill bit or a drill bit and a reamer and the step of drilling with a water drill bit.

8. The method according to claim 6, wherein the conductive casing is configured as a structural support for the remainder of the productive life of the well.

9. The method according to claim 6, wherein, Riserless Mud Recovery (RMR) technology is used in in the step of drilling with a water drill bit.

10. The method according to claim 6, wherein a production casing is run in with tubes in the step of drilling with a water drill bit, wherein the tube have a length from 9? (24.45 cm) to 14 (35.56 cm) or from 4? (11.43 cm) to 9? (24.45 cm).

11. The method according to claim 6, further comprising wireline logging occurs to acquire reservoir data after drilling to a final programmed depth.

12. The method according to claim 6, further comprising a fluid exchange optionally after drilling to a final programmed depth, wherein the fluid exchange occurs if there is incompatibility of the completion equipment and stimulation system with the drilling fluid.

13. The method according to claim 6, wherein the production casing has a length of 11? (30.16 cm) and the section of the production string has a length of 7? (19.37 cm).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] In order to complement the present description and obtain a better understanding of the features of the present invention, and in accordance with a preferred embodiment thereof, in the annex, a set of figures is presented, where in an exemplified, although not limiting, manner, its preferred embodiment is represented.

[0024] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.

[0025] FIG. 1 represents a general diagram of well drilling with phases 1 (F1), 2 (F2) and 3 (F3), according to a preferred embodiment of the present invention.

[0026] FIG. 2 represents a schematic drawing of Phase 1 (F1) of the 2R-PAC system and method, according to a preferred embodiment of the present invention.

[0027] FIG. 3 represents a schematic drawing of Phase 2 (F2) of the 2R-PAC system and method, according to a preferred embodiment of the present invention.

[0028] FIG. 4 represents a schematic drawing of Phase 3 (F3) of the 2R-PAC system and method, according to a preferred embodiment of the present invention.

[0029] FIG. 5 represents a schematic drawing of the completion string of the associated 2R-PAC system and method, according to a preferred embodiment of the present invention.

[0030] FIG. 6 represents a schematic drawing of the 2R-PAC system and method, highlighting each component, according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention refers to a system and method for constructing and completing wells in pre-salt producing and injecting fields. As shown in FIG. 6, the system comprises subsea equipment (1) (e.g. PAB and WCT which contains monitoring system and valves to enable well operation), wellhead media (2), drilling and completion fluid (3), cement (4), casings (5), production string (6), string accessories (7), DHSV (8), HFIV (9), Packer (10) and AMB (11).

[0032] These system and method, called 2R-PAC (2 Casing-Completed Open Well) reduces one phase of the well, thus resulting in 3 (three) drilling phases, with the running in of only 2 (two) casings and completion in an open well with part of the same exposed to the saline formation, as shown in FIG. 1. This allows a reduction in construction time, which also results in a reduction in the total cost of the well, thus reducing the costs of the well area for the project, improving its economy.

[0033] As shown in FIG. 2, the method of the present invention begins (Phase 1 or F1) with the drilling with a drill bit or drill bit and reamer, subsequently running in a 30 (76.2 cm) or 36 (91.44 cm) conductive casing, or starting a blasted well with the use of 30 (76.2 cm) or 36 (91.44 cm) conductive casing, with open sea setting string and cementing until the seabed of the casing, in both cases using seawater and drilling fluid. This casing must provide structural support for the remainder of the productive life of the well.

[0034] As shown in FIG. 3, in Phase 2 or F2, the phase is drilled with a drill bit using seawater and water-based drilling fluid until close to the base of the saline formation, maintaining a minimum distance above the reservoir, considering the uncertainties of seismic, string length, minimum extent of sealing formation, etc., to avoid the risk of leakage to the seabed, as there is still no BOP installed at this step.

[0035] The positioning of this shoe must be able to withstand the reservoir pressure in the next phase considering that the well may be full of reservoir fluid. The strategy of drilling with seawater and drilling fluids, and composition of the drilling fluids, is projected and suitable for the location in order to prevent formation breakout.

[0036] RMR (Riserless Mud Recovery) technology can also be used at this phase. At this phase, a production casing is run in with pipes that can vary from 9? (24.45 cm) to 14 (35.56 cm) depending on the diameter of the completion string, which can vary from 4? (11.43 cm) to 9? (24.45 cm) depending on the project requirement.

[0037] As shown in FIG. 4, in Phase 3 or F3, the phase is drilled until the final programmed depth of the well, drilling the remainder of the saline formation and the reservoir with synthetic- or water-based fluid with adequate formulation and salinity to avoid the dissolution of the salt. At the end of the phase, wireline logging may occur to acquire reservoir data, as well as fluid exchange may be necessary, if there is incompatibility of the completion equipment and stimulation system with the drilling fluid to be used. In the 2R-PAC conception, the casing is not run in and, the completion is carried out in an open well.

[0038] The installation of the lower completion, in this scenario, has an additional function, in addition to allowing the production of fluid from the reservoir or injection of water or gas, of isolating the saline formations from the production or injection flow that will be exposed in phase 3; therefore, elements of the tail in front of the salt must withstand the forces arising from its creep.

[0039] In addition, there may be unfavorable geometric conditions for the passage of the lower completion due to intercalations in the saline formation; in this way, the lower tail equipment is designed and chosen in order to minimize the risks of bumping, including considering the possibility of carrying out the string rotation to facilitate the running in of equipment.

[0040] The interface between the base of the saline formation and the top of the reservoir also configures a point of transition of properties, with potential generation of stop. Due to the exposed saline section, the running in of the lower tail may be in a synthetic fluid environment; therefore, the stimulation and fluid exchange strategy for the scenario shall consider the pumping of cushions and compatible acids to stimulate the formation. Thus, it is noted that the 2R-PAC concept allows the production casing section to be 11? (30.16 cm) and, thus, the production string section can be 7? (19.37 cm).

Chronological Description of the Well Construction Steps

[0041] The 2R-PAC well conception occurs by constructing the well, following the following macro steps of the process: 1. Drilling with a 36 (91.44 cm) or 42 (106.68 cm) drill bit and drill string using seawater and drilling fluid. 2. Installation of 30 (76.2 cm) or 36 (91.44 cm) conductive casing with open sea laying string and cementing to the seabed of the casing. 3. Drilling with a 12? (31.12 cm) or 14? (37.47 cm) drill bit of post-salt and salt with seawater and drilling fluid until the final depth of the phase.

[0042] The times for using the drilling fluid are defined based on the features of each well, and it is necessarily used in the last 500 m of the phase to preserve the quality of the well for running in of the casing and casing cementation. 4. Installation of the 9? (24.45 cm) or 10? (27.31 cm) or 11? (30.16 cm) production casing with open sea setting string and cementing of the casing in footage designed to establish the joint sets of barriers necessary for the remainder of its life well productivity.

[0043] 5. Installation of the PAB (Production Adapter Base) at the wellhead with SESV (Subsea Equipment Support Vessel) 6. Installation and testing of the BOP (Blow-out Preventer) at the PAB. 7. Drilling with an 8? (21.59 cm) drill bit from the salt and reservoir with drilling fluid (water-based or synthetic) until the final depth of the well. 8. Exchange of drilling fluid for completion fluid. 9. Assembly of the lower completion tail. 10. Running in the lower tail assembly with string to the setting position.

[0044] 11. Pre-stimulation of the reservoir through the positioning of cushions and acids by circulation or direct injection (bullheading) into the reservoir (design and composition of acids and cushions according to the features of each reservoir). 12. Setting of the packer seal bore and AMBs (Annular Mechanical Barriers).

[0045] 13. Stimulation of the reservoir by pumping cushions and acids by direct injection (bullheading) into the reservoir (design and composition of acids and cushions according to the features of each reservoir). 14. Closing the FIV valve and removing the lower tail installation tool. 15. Withdrawal of Wear Bushing (WB) from PAB.

[0046] 16. Assembling the upper completion string 17. Running in of the upper completion with DPR (Drill Pipe Riser). 18. Setting of the TH (tubing hanger) and carrying out pressure tests to ensure equipment integrity. 19. Reservoir stimulation. 20. Prevention of hydrates in the WCT and string with MEG and/or diesel positioning to a position below the DHSV. 21. Closure of DHSV. 22. Withdrawal of the TH installation tool. 23. Disconnection and withdrawal of the BOP. 24. Installation of WCT (Wet Christmas Tree) with SESV.

[0047] The components and their respective position in the lower or upper completion may vary according to the objectives of each well, such as, well function (producer or injector), presence and quantity of ICV valves, gas lift mandrels and chemical injection, PDGs, DHSV, among others.

[0048] With the application of this system and method, compared to the application of the typical system and method, there is a reduction in well construction time of approximately seven days considering the drilling and completion of the well. Other gains in the configuration are not needing a drill through wellhead system, which is a limited resource in wells, taking advantage of the optimization of the PAB installation combined with SESV even during the running in of the BOP from the probe (out of the way critical). Furthermore, the well has no pack-off (CVU), presenting less restriction on the production loads of the well.

[0049] Those skilled in the art will value the knowledge presented herein and will be able to reproduce the invention in the presented embodiments and in other variants, encompassed by the scope of the attached claims.