WO2015054766A1

WO2015054766A1 - A process for installing an integral assembly consisting of suction pile and conductor casing

Info

Publication number: WO2015054766A1
Application number: PCT/BR2014/000375
Authority: WO
Inventors: John Mathew Riggs; Cleiver FERRAZ MOULIN DOS REIS; Ariel DE SILVIO; Pedro Luiz DE SOUZA PINTO FILHO
Original assignee: Intermoor Do Brasil Serviços Offshore De Instalação Ltda.
Priority date: 2013-10-18
Filing date: 2014-10-17
Publication date: 2015-04-23
Also published as: BR102013026949A2

Abstract

The present invention relates to a process for installing an integral assembly, comprising a first penetration step that takes place by means of the weight itself of the assembly, and a second penetration step that takes place by suction for completing the penetration of the assembly into the sea floor. Additionally, the present invention discloses the integral assembly itself having particularly one or more suction piles associated to one or more conductor casings.

Description

Specification of the Patent of Invention for: "A PROCESS FOR INSTALLING AN INTEGRAL ASSEMBLY CONSISTING OF SUCTION PILE AND CON- DUCTOR CASING"

The present invention relates to a process for installing an inte- gral assembly, which occurs initially by the weight of the assembly itself and in a second stage by suction. In addition, the present application relates to the integral assembly itself, which contains one of more suction piles and one or more conductor casings, particularly used for imparting structural stiffness and to support the stresses transferred in an oil well.

STATE OF THE ART

Various systems have been developed in the state of the art with regard to the conductor casings and processes for installing them.

However, all the developments found in the prior art have certain procedure difficulties, these problems being solved with the present inven- tion.

Actually, such problems refer directly to the logistics employed in the procedures, which causes an expressive increase in the costs.

At present, a conductor casing, equipment used for decades by the oil drilling industry, is installed by means of the drilling rig as an operation of its working schedule.

For said installation of the conductor, some methods may be used, such as the installation of conductor casing by using a rig, and installation of the conductor casing by using an AHTS-type vessel.

The installation of the conductor casing by using a rig may take place through jetting, wherein said conductor casing runs down to the ocean floor in conjunction with the drill bit of smaller diameter. This drill bit has orifices through which water is jetted against the floor, thus generating an opening wider than the diameter of the conductor casing, which is fitted and finally cemented in the region of contact with the soil and installed.

Another form of installing a conductor casing by using a rig is drilling, wherein said conductor runs down to the ocean floor in conjunction with the drill bit with adjustment of the diameter, and the latter applies a rota- tion force for drilling the floor, generating an opening broader than the diameter of the conductor casing, after which the latter is fitted, cemented in the region of contact with the soil and installed.

Further, there is the installation of a conductor casing by using an AHTS-type vessel. This technique is described in document BR071 967 (In- terMoor - priority date of July 20, 2005), which refers to a method for pre- installing conductor casings by using a hydraulic hammer. An anchor handling vessel (AHTS) is employed to launch and penetrate the conductor casings into the ocean floor. Said conductors initially penetrate the sea floor until a first depth under its self weight, and the installation is completed by using a hydraulic hammer. In this method, the conductor is installed prior to the arrival of the drilling rig at the well location, which excludes the operation of the working schedule of the platform, thus reducing the total time required for drilling the well.

The first two installation techniques which employ a rig. mentioned above, raise the costs of the drilling procedures, mainly because the daily rate of the rig is high. In addition, this causes the conductor to have a longer length, as a function of the smaller area of steel driven into the sea floor. Further, there is the need to cement the clearance between the conduc- tor and the floor in order to seal it and increase the vertical and horizontal structural capacity of the well.

As far as the hydraulic-hammer technique is concerned, although this is an advantageous method for pre-installing conductor casings on the sea floor, this technique needs an AHTS-type vessel and is not feasible for the installation of 3 (three) or less conductor casings.

Therefore, the problems related to installing conductor casings for the purpose of drilling in maritime waters have brought great challenges. On the other hand, the state of the art has not found an adequate solution for installing conductors without using a rig and without using a hydraulic ham- mer, which have a high daily cost and require the cementation process and a longer length of the conductor casing for the drilling process. With reference to the state of the art, the following documents have been identified, which comprise more relevant technologies related to the present invention.

Document US 4830541 (SHELL OFFSHORE INC., priority date of May 30, 1986), relates to a wellhead apparatus and a method for positioning the apparatus, at the ocean floor, besides means for penetrate it into the sea floor. In this case, the apparatus is equipped with a suction device and a central opening for receiving the conductor casing subsequently. The apparatus also provides a base structure, which can be controlled during the in- stallation, to be positioned with a predetermined angle relative to the vertical.

The document cited above describes the installation of a device for wellhead, which does not dispense with the use of rig for installing the conductor casing. Therefore, this does not aid in solving the problems presented in this specification, since it does not deal specifically refers to the installation of the conductor casings themselves.

Document US 6692194 (STRAND HARALD, priority date of February 29, 2000) proposes the installation of a suction pile on the sea floor and then the installation of the conductor casing.

The document cited above describes an assembly that^' does not integrate the pile with the conductor casing, unlike what the present invention proposes. In addition, it does not dispense the use of a rig for installing the conductor casing.

BRIEF DESCRIPTION OF THE INVENTION

It is^' an objective of the present invention to provide a process for installing an integral assembly, wherein a first penetration step takes place by means of the assembly weight itself, and a second step takes place by means of suction to complete the penetration of the assembly into the sea floor. Additionally, the present invention discloses the integral assembly itself particularly containing one or more suction piles associated to one or more conductor casings. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood with basis on the following description, taken in conjunction with the attached drawings, wherein:

Figure 1 shows a detailed model of the external part of an assembly containing a conductor 1 , a low-pressure housing 2, a suction pile 3, padeyes 4, connector for suction pump 5, working platform 6, water outlet valve 7 and spirit level 8.

Figure 2 shows a detailed model of the internal part of an as- sembly containing a conductor, wherein the internal reinforcements 9 between the conductor casing 1 and the suction pile 3 are presented.

Figure 3 is a sectional side view of the assembly with a conductor casing 1 on a suction pile 3 with initial penetration due to the assembly weight and start of the penetration by suction into the sea floor 10.

Figure 4 is a sectional view of the assembly with a conductor casing 1 on a suction pile 3 at the end of the penetration by means of suction into the sea floor 10.

Figure 5 is a sectional side view of the assembly with various conductor casings 3 with initial penetration by the system weight and initial of the penetration by suction.

Figure 6 is a sectional side view of the assembly with various conductor casings 1 in the intermediate region of two suction piles 3 with the initial penetration by means of the system weight and start of the penetration by suction.

Figure 7 is a plan view of several assemblies, each assembly comprising a number of conductor casings 1 in the central region of a suction pile 3 having the shape of a regular polygon, with initial^' penetration by the system weight and start of penetration by suction.

• Figure 8 is a sectional side view of the assembly with a number of conductor casings 1 coupled to the suction pile 3 with the shape of a regular polygon, with initial penetration by the system weight and start of penetra_¬ tion by suction. DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in greater details as shown in the attached drawings.

As mentioned above, the prior art has problems to be solved with regard to the installation of conductor casings for use in drilling oil wells in the sea floor.

In order to solve the problems presented and involved in the systems used so far by the prior art, regarding the installation of conductor casings for use in drilling oil wells in the sea floor, the present invention proposes an integral assembly containing the items below (models presented in figures 1 and 2):

(a) Conductor casing 1 ;

( ) Low-pressure housing, which is a part of the conductor casing 2;

(c) Suction pile 3;

(d) Padeyes 4;

(e) Connector for suction pump 5;

(f) Working platform 6 on the suction pile;

(9) Water outlet valves 7;

(h) Spirit level 8; and

(i) Internal and external structural reinforcements 9 between the conductor casing and the suction pile.

The integral assembly shown in figures 1 and 2 has only one conductor casing. However, the integral assembly may be presented in other geometric forms, containing a series of conductor casings and more than one suction pile, like those shown in figures 5 to 8.

For conforming such an assembly, the conductor casing and the suction pile should be integral.

The conductor casing is designed to have a diameter ranging from 50.8 to 150 centimeters and a length ranging from 20 to 100 meters, while the suction pile is designed to have a diameter ranging from 2 to 8 meters and a length ranging from about 5 to 40 meters, being shorter than the length of the conductor casing, depending on the characteristics of the floor. The structural reinforcements shown in figure 2 should be manufactured with plates of small thickness. These internal reinforcements should be present to ensure that the conductor and the pile will be kept coaxial. On the other hand, they may not render the penetration into the floor difficult.

The structures described, that is, conductor casing, suction pile and structural reinforcements, exhibit an area of contact with the floor that is much larger in comparison with said assembly. This fact imparts more resistance to both the vertical forces and to the moment exerted by the drilling column or production equipment. The consequences of this greater re- sistance will be a shorter conductor.

In addition to the data presented above, there is a larger area on the suction pile, which may be used for arranging working tools during the drilling. This area has been called working platform in this invention.

A few tools that can be handled on this platform are cited herein- after:

(a) guide wires between the padeye of the pile and the surface platform. With appropriate tension, it can be used in guiding the ROV (Remote Operated Vehicle) or other tools. This cable becomes important in fields having strong streams;

(b) fixed cameras for monitoring the wellhead. This monitoring is made by the ROV, which may be difficult with strong streams;

(c) handlers, which can perform tasks as an option to the ROV.

These handlers are similar to the ROVs, but they do not have the complete propelling system; and

(d) support for drilling tools like the BOP (Blow-Out Preventer) or the

Drilling Risers.

Other similar tools may be used on the working platform for aiding in the drilling and/or continuation of the functioning of the drilled well.

For the process of installing the integral assembly described above, a vessel is used, more specifically, a vessel with a winch and/or a crane. Due to the fact that the assembly is integral, only one structure is lowered until the sea floor. Upon reaching the floor, there is an initial penetration with the weight itself of the parts. This initial step is important because it is necessary to ensure that the conductor will penetrate sufficiently, so that the suction pile can initiate the second penetration step. The initial penetration is generally established between about 5 to 15 meters in depth in the sea floor.

With the pile in contact with the floor, a sealed compartment is formed by the floor itself, side and top walls of the suction pile, in besides the conductor itself internally. The conductor casing is a bored-through pipe. Therefore, it is extremely important to seal this suction chamber completely during the manufacture of the structure.

The second part of the penetration takes place through the functioning of the suction pump, which completes the penetration of the whole integral assembly into the sea floor.

This installation process can be used for several geometric models of integral assemblies containing one or more conductor casings, besides also containing one or more suction piles, and it can be seen in the attached figures. Besides that, the same process can be used for installing other piec- es of equipment, such as: anchors, piles, pillars or any other equivalent structural elements.

Despite the above description of the present invention and the attached illustrative figures, a person skilled in the art will be able to analyze and conclude that there are variations within the embodiments, in addition to those specified herein.

Claims

1. A process for installing an integral assembly, characterized by having a first penetration step by means of the weight itself of the parts and a final penetration step by suction.

2. The process according to claim 1 , characterized in that the initial penetration by means of the weight itself takes place between about 5 and 15 meters in depth in the sea floor (10).

3. The process according to claim , characterized by forming a sealed compartment between the floor (10), side and top walls of the suction pile (3), besides the conductor casing (1 ) itself.

4. The process according to claim 1 , characterized by using any type of vessel.

5. The process according to claim 4, characterized by preferably using a vessel with a winch and/or a crane.

6. The process according to claim 1 , characterized also by installing anchors, piles, pillars or any other equivalent structural elements.

7. An integral assembly, characterized by comprising one or more conductor casings (1 ), one or more low-pressure housings (2), one or more suction piles (3), padeyes (4), structural reinforcements (9), one or more working platforms (6) on the suction pile, and accessories needed for the operation of the integral assembly.

8. The integral assembly according to claim 7, characterized in that the conductor casing (1) has a diameter ranging from 50.8 to 150 centimeters and a length ranging from 20 to 100 meters.

9. The integral assembly according to claim 8, characterized in that the conductor casing (1) has preferably a diameter ranging from 76.2 to 121.9 centimeters and a length ranging from 20 to 60 meters.

10. The integral assembly according to claim 7, characterized in that the suction pile (3) has a diameter ranging from 2 to 8 meters and a length preferably ranging from 5 to 40 meters, being shorter than the length of the conductor casing (1).

11. The integral assembly according to claim 10, characterized in that the suction pile (3) has preferably a diameter ranging from 20 to 6 meters and a length of about 5 to 15 meters, being shorter than the length of the conductor casing (1).

12. The integral assembly according to claim 7, characterized in that the structural reinforcements (9) are arranged internally and externally on said integral assembly.

13. The integral assembly according to claim 7, characterized in that the working platform (6) enables the handling of tools such as (a) guide wire between the pile padeye and the surface platform; (b) fixed cameras for monitoring the wellhead; (c) handlers that can perform tasks as an option to an ROV; (d) support for drilling tools such as a BOP (Blow-Out Preventer) or the drilling risers; and other similar tools.