Maritime drilling with fluid reverse circulation without using drilling riser

Abstract

The present invention refers to a method of drilling a marine wellbore with fluid reverse circulation without using drilling riser tubulars. In reverse circulation drilling, the fluid return with gravels occurs inside the drill string (17) and the injection of clean fluid is done through the annular of the well, so that, having a rotating head over the BOP (19), or inside it, the use of riser tubulars as a flow line for the fluid return with gravels is disposed, using instead the drill string (17). For the kill and choke lines, as well as for fluid injection, rigid or flexible lines can be used, eliminating the need to use drilling risers, thus releasing large load capacity and space on the probe. The method of this invention also eliminates the need for large volumes of fluid to fill entire riser tubulars. The entire operation can be done without the need for subsea pumps or concentric columns. Additionally, the invention makes the operation of lowering the drilling riser tubulars unnecessary, which lasts for days and has a high cost. Finally, for dual activity probes, the arrangement allows the use of the two towers even after connecting the BOP (19), something that is not possible with the use of drilling riser tubulars. Therefore, operations such as mounting and lowering the casing in the water depth can be carried out in parallel with the drilling of the phase, allowing a significant additional gain of time.

Claims

1. A method of drilling a maritime wellbore with a maritime drilling system configured for fluid reverse circulation without using drilling riser tubulars, characterized by drilling operations without a riser and with reverse circulation, the method comprising: lowering an injection flexible line (12) of the maritime drilling system from a reel (11) simultaneously with lowering a blow-out preventer (BOP) (19) of the maritime drilling system; pumping drilling fluid through the injection flexible line (12), supported on the reel (11), of the maritime drilling system such that the drilling fluid is injected below an underwater rotating head with a double seal (13) of the maritime drilling system; providing, after the drilling fluid is injected, the drilling fluid through a cased bore annular (14) and through an open wellbore annular (15) of the maritime drilling system; providing, after the drilling fluid is provided through the cased bore annular (14) and the open wellbore annular (15), the drilling fluid through a drill bit (16) of the maritime drilling system, taking cut gravel with the drilling fluid during drilling; and returning, after the drilling fluid is provided through the drill bit (16), the drilling fluid through a drill string (17) of the maritime drilling system.

2. The method according to claim 1, wherein the BOP (19) of the maritime drilling system is lowered using a laying column (31) of the maritime drilling system.

3. The method according to claim 1, wherein the BOP (19) of the maritime drilling system is lowered using a cable (22) of the maritime drilling system.

4. The method according to claim 3, wherein the injection flexible line (12) is lowered from the reel (11) simultaneously with lowering the blow-out preventer (BOP) (19) of the maritime drilling system from another reel.

5. The method according to claim 4, further comprising connecting the injection flexible line (12) after lowering the injection flexible line (12).

6. The method according to claim 2, further comprising using jets of a positioning system (44) to facilitate connection of the BOP (19) with a wellhead or with a production adapter base (BAP).

7. The method of claim 2, further comprising using propellers of a positioning system (44) to facilitate connection of the BOP (19) with a wellhead or with a production adapter base (BAP).

8. The method according to claim 2, wherein the maritime drilling system further includes a casing valve (18) that is configured as a safety barrier for removal of the drill string (17).

9. The method according to claim 2, wherein the BOP (19) is configured to allow withdrawal of the drill string (17) without fluids leaking into the sea.

10. The method according to claim 2, further comprising connecting the laying column (31) to the BOP (19) by a connector (51), when installing the BOP (19).

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The present invention will be described in more detail below, with reference to the attached figures which, in a schematic form and not limiting the inventive scope, represent examples thereof. In the drawings, there are:

(2) FIG. 1 illustrating the system while drilling a wellbore without the riser tubulars connected to the BOP and with reverse circulation of drilling fluid;

(3) FIG. 2 illustrating the system during lowering of the BOP by cable;

(4) FIG. 3 illustrating the alternative system of lowering the BOP using a laying column;

(5) FIG. 4 illustrating the system for lowering and positioning the BOP over the wellhead when, optionally, lowered with a cable;

(6) FIG. 5 illustrating the system for lowering and positioning the BOP over the wellhead when, optionally, lowered with the laying column.

DETAILED DESCRIPTION OF THE INVENTION

(7) Preliminarily, it is noted that the following description will start with the preferred embodiments of the invention. As will be apparent to any person skilled in the art, however, the invention is not limited to these particular embodiments, but rather to the scope defined in the claims.

(8) FIG. 1 shows the system during the drilling operation without riser tubulars and with fluid reverse circulation. In this system, the pumped drilling fluid passes through the reel (11) and the flexible line (12), being injected below the underwater rotating head with double seal (13). The fluid goes through the cased well annular (14) and through the open well annular (15). It then enters through the drill bit (16), taking with it the cut gravel during drilling, and returns through the drill string (17). In this situation, the casing valve (18) serves as a safety barrier for the withdrawal of the drill string (17). Finally, the BOP (19) is used as safety equipment for eventual emergencies and as a cleaning tool to enable the removal of the column without the leakage of fluids into the sea. The lowering of the BOP (19) can be done using a laying column or a cable.

(9) FIG. 2 describes the system during the lowering of the BOP (19) with cable system (22) and the reel with the lowering cable (21). Optionally, the flexible lines (12) can be lowered from a similar reel (11) simultaneously with the lowering of the BOP (19).

(10) FIG. 3 illustrates an alternative system of lowering the BOP (19) using a laying column (31). Optionally, flexible lines (12) can be lowered from a reel (11) simultaneously with the lowering of the BOP (19).

(11) FIG. 4 describes the system for lowering and positioning the BOP when, optionally, lowered with a cable. FIG. 4 represents the entire BOP. Therein, the cable is connected to the BOP by a connector (41) and the injection lines are connected by another connector (42). There is a positioning system (44) to facilitate connection to the wellhead or the BAP (Production Adapter Base). This positioning system can optionally be driven by propellers or jets. There is also the underwater rotating head with double seal (13), the annular BOP (46), the drawers (47), and the upper (43) and lower (48) hoppers.

(12) FIG. 5 shows the lowering and positioning system of the BOP when, optionally, lowered with a laying column (31). FIG. 5 represents the entire BOP. Therein, the laying column (31) is connected to the BOP by a connector (51), and the injection lines are connected by another connector (42). There is also the underwater rotating head with double seal (13), the annular BOP (46), the drawers (47), and the upper (43) and lower (48) hoppers.

(13) Numerous variations focusing on the protection scope of this application are allowed. Thus, it reinforces the fact that the present invention is not limited to the particular configurations and embodiments described above.