BR-102021005383-B1 - METHOD OF DRILLING AN OFFSHORE WELL HOLE WITH REVERSE FLUID CIRCULATION WITHOUT USING DRILLING RISER TUBES

BR102021005383B1BR 102021005383 B1BR102021005383 B1BR 102021005383B1BR-102021005383-B1

Abstract

OFFSHORE DRILLING WITH REVERSE FLUID CIRCULATION WITHOUT THE USE OF A DRILL RISER. The present invention relates to a method of drilling an offshore well hole with reverse fluid circulation without using drilling riser tubing. In reverse circulation drilling, the return of the fluid with cuttings occurs inside the drill string (17) and the injection of clean fluid is done through the well annulus, so that, having a rotating head on or inside the BOP (19), the use of riser tubing as a flow line for the return of the fluid with cuttings is dispensed with, using the drill string itself (17) instead. For 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 freeing up significant load capacity and space on the rig. The method of this invention also eliminates the need for large volumes of fluid to fill all the riser tubing. The entire operation can be performed without the need for subsea pumps or concentric columns. Additionally, the invention eliminates the need for lowering the tubular pipes (...).

Inventors

JOSEIR GANDRA PERCY
RONI ABENSUR GANDELMAN
GUILHERME RIBEIRO MAGALHAES
EMILIO CESAR CAVALCANTE MELO DA SILVA
GUILHERME SIQUEIRA VANNI
AUGUSTO BORELLA HOUGAZ
JOÃO CARLOS RIBEIRO PLACIDO
Hugo FRANCISCO LISBOA SANTOS

Assignees

Petróleo Brasileiro S.A. - Petrobras

Dates

Publication Date: 20260317
Application Date: 20210322

Claims (10)

1- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, characterized by drilling operations without a riser and with reverse circulation, the method comprising: - lowering a flexible injection line (12) from a reel (11) simultaneously with lowering a blowout preventer (BOP) (19); - pumping drilling fluid through the flexible injection line (12), supported on the reel (11), so that the drilling fluid is injected below a subsea rotating head with a double seal (13); - providing, after the drilling fluid is injected, the injection fluid through an annulus of the cased well hole (14) and through an annulus of the open well hole (15); - providing, after the drilling fluid is provided through the annulus of the cased well hole (14) and the annulus of the open well hole (15), the drilling fluid through a drill bit (16), carrying cuttings with the drilling fluid during the drilling; and returning, after the drilling fluid is supplied through the drill bit (16), the drilling fluid through a drill string (17).
2- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser pipes, according to claim 1, characterized in that the BOP (19) is lowered using a setting string (31).
3- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 1, characterized in that the BOP (19) is lowered using a cable (22).
4- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 2 or 3, characterized in that the flexible injection line (12) is lowered from the reel (11) simultaneously with lowering the BOP (19) from another reel.
5- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 4, characterized by further comprising connecting the flexible injection line (12) after descending the flexible injection line (12).
6- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 2 or 3, characterized by further comprising using jets from a positioning system (44) to facilitate connection of the BOP (19) with a wellhead or with a production adapter base (BAP).
7- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 2 or 3, characterized by 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- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubing, according to claim 2 or 3, characterized by acting a casing valve (18) as a safety barrier for the removal of the drill string (17).
9- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubulars, according to claim 2 or 3, characterized in that the BOP (19) allows the removal of the drill string (17) without fluid escaping into the sea.
10- Method of drilling a marine well hole with reverse fluid circulation without the use of drilling riser tubing, according to claim 2, characterized by further comprising connecting the string (31) to the BOP (19) by a connector (51), when installing the BOP (19) by the string (31).

Description

Field of Invention [0001] The present invention relates to a method of drilling a marine well hole with reverse fluid circulation, without using tubulars connecting the drilling rig to the well, called a drilling riser, and can be applied to marine well holes that are constructed using single rigs or dual-activity rigs, such as deepwater or ultra-deepwater offshore wells, with the primary function of increasing operational efficiency and reducing the cost of drilling a well hole. Description of the State of the Art [0002] Drilling deepwater oil wells presents several challenges, one of which is the need to use a large number of tubular riser joints. Each joint is heavy (approximately 32,000 lb or 15 tons) and large (approximately 23 m long and 21 in in diameter). Another challenge is the demand for larger capacity fluid circulation system tanks. Just to fill the riser tubulars, a volume of approximately 470,000 liters (3,000 bbl) is required for a water depth of 2,500 m. A third challenge is the need to use higher flow rate pumps to allow for the transport of cuttings inside the riser. [0003] In addition to the technical challenges, there are also economic issues, since offshore drilling rigs have a high daily operating cost. Rigs currently account for about 50% of the cost of drilling a well and are paid for per day worked. Furthermore, other services performed are also paid for per day available or per day worked. Lowering the riser pipes, in particular, is an activity that demands a large number of hours. In offshore wells with water depths greater than 1,500 m, several days are spent on the well construction phase due to the long distance to be covered in maneuvers because of the stretch of sea. [0004] The traditional solution for drilling in deeper water has been the adoption of thicker-walled riser pipes and rigs with more pumps and greater load capacity. However, an alternative solution has been under study for almost two decades: performing operations without riser pipes. In the configurations typically suggested, subsea pumps are used for the return of the fluid with cuttings (US20160047187A1), or concentric strings are used (US20170058632A1). However, the use of subsea pumps introduces a component of low reliability into the system. In addition, it adds complexity to the assembly, as it replaces riser pipes, which are components without moving parts and with a low failure rate, with subsea pumps, which have moving parts and a high failure rate. [0005] On the other hand, in order to increase operational efficiency and reduce costs, attempts are made to decrease the total well construction time. One way to do this is to perform as many operations as possible in parallel. For example, cargo transfer and handling operations are almost all performed in parallel. Similarly, the equipment that will descend into the wellbore is prepared hours or even days in advance. [0006] Thus, some systems have been proposed that allow other operations to be bypassed from the critical path and performed in parallel. One of these proposals is the use of dual-activity probes (patent EP1277913B1). These probes allow some operations to be performed simultaneously on each of the towers, removing the faster operation from the critical path. However, their advantage is limited to situations where the BOP (Blowout Preventer) and the riser tubing are not positioned at the wellhead. When the BOP and the riser tubing are connected, all operations must be performed via a single path. [0007] The reverse fluid circulation drilling technique was implemented from 2006 onwards as a way to improve cuttings cleaning efficiency in critical hydraulic scenarios in onshore wells, and is described in patent PI0605527-3B1. [0008] Document PI0605527-3B1 describes a method for drilling wells with reverse fluid circulation used to remove cuttings resulting from this operation. The method consists of using a rotating annular isolation device that allows pumping fluid to remove cuttings through the annular space formed between the drill string and the wellbore wall. This fluid reaches the bottom of the well, penetrates the drill string through the drill bit(s), and carries the cuttings to the surface of the drill string. The fluid is diverted, at the top of the drill string, to a cuttings separation unit, where the cuttings are separated from the fluid. The fluid is then conveyed to the storage tank, from where it is drawn up by a pumping unit and then pumped back into the annular space of the well. For the application of the method, it is necessary that the annular space be isolated from the atmosphere by a rotating annular isolation device. Unlike the present invention, the previous work deals with reverse circulation drilling in onshore wells, where a drilling riser is no longer used. In the present invention, the proposal is for reverse circulation drilling in offshore wells without this equipment. [0009] The method of the present invention rel