EP1444415B1

EP1444415B1 - Single well development system

Info

Publication number: EP1444415B1
Application number: EP02801382A
Authority: EP
Inventors: Brian William Lane
Original assignee: Alpha Thames Ltd
Current assignee: Alpha Thames Ltd
Priority date: 2001-10-12
Filing date: 2002-10-11
Publication date: 2006-05-17
Anticipated expiration: 2022-10-11
Also published as: DE60211544D1; BR0213625A; US20040251030A1; WO2003033868A8; NO20041929L; WO2003033868A1; ATE326611T1; GB0124612D0; EP1444415A1

Abstract

A single well development system has a base structure (8) through which the well is drilled and completed by means of a wellhead (6). A retrievable Christmas tree module (10) containing a Christmas tree (12) connected to wellhead connector (14) is mounted on the base structure (8) by the wellhead connector (14) so as to receive well fluid from the wellhead. The module (10) contains two fluid processing separators (16) for processing fluid received from the well via the wellhead (6) and the Christmas tree (12). In a modification, additional modules are mounted on the base structure and each additional module has a fluid processing separator (16), and the Christmas tree module routes production fluid to the separators via the base structure (8).

Description

The present invention relates to the economically viable extraction of hydrocarbon reserves from a single sub-sea well.
Existing single well developments are generally connected to a host facility which is often located remotely from the well, where processing equipment is situated. In situations in which the well has insufficient drive or pressure, pressure boosting of production fluid by means of a pump is required. The flow may suffer from one of a number of flow assurance problems such as: (i) slug flow (flow containing slugs of gas and/or liquid); (ii) the formation of hydrates; (iii) corrosion; and (iv) sand precipitation. The provision of separate structures for treating the flow from a single well and the consequent requirement for interconnections between the wellhead and the structures may not be economically viable when only a single well is concerned.
WO-A 0047864 discloses a single well development structure having a base structure framework. One side of a housing for a wellhead is placed at one end of the framework and the framework is then extended from the other side of the wellhead housing. A conventional christmas tree is fixed to the top of the wellhead housing and a barrier module and a process module are connected to the framework by respective connector hubs. The process module can contain a separator.
The object of the invention is to overcome at least some of the above-mentioned problems and provide a means by which a single sub-sea well field can be economically developed.
Thus according to the invention there is provided a single well development system comprising a base structure, a wellhead completing a well, and a retrievable christmas tree module including a christmas tree and connecting means for connecting the christmas tree module to the wellhead so as to receive well fluid therefrom, characterized in that:

the retrievable christmas tree module includes fluid processing means for processing fluid received from the well via the wellhead and christmas tree; and
the base structure has the well drilled through it.

The christmas tree module is primarily supported by means of its connection to the wellhead. The base structure and/or the christmas tree module may include supplementary support means for the christmas tree module which is independent of the wellhead connecting means.
Conveniently the system indudes at least one fluid connector, the or each fluid connector comprising first and second engageable portions, the first portion forming part of said retrievable module and the second portion forming part of the base structure. The engageable portions may each include plural passageways for separate fluid flows and may form part of the connecting means for connecting the christmas tree to the wellhead.
The retrievable christmas tree module may include a power and/or control pod.
Preferably, the system indudes at least one electrical connector, the or each electrical connector comprising first and second interengageable portions, the first interengageable portion forming part of said retrievable module and the second interengageable portion forming part of the base structure. The first interengageable portion is connected to the power and/or control pod in the module.
The base structure may comprise a drilling template for drilling a well.
The base structure may include means for guiding the retrievable module onto the base structure. In addition, the base structure may have means for supporting the retrievable module.
The base structure based second engageable portion of the fluid connector may be connected to a flow line connection for conveying fluid from the base structure to one or more extemal flow lines.
The connection means preferably also includes an electrical connector as described above. The base structure second interengageable portions of the electrical connector may be connected to an integrated service umbilical for receipt by the system of electrical power and/or control signals, injection chemicals for addition to fluids acted on by the system etc.
Fluid processing means in the module may comprise one or more separators, such a gravity separators, hydrocyclones etc. The flows through which may be controlled by means of flow control valves, preferably electrically actuated which may be adjusted under control of a power and/or control pod.
The invention also provides a method of exploiting the output from a single well, comprising the steps of:

(i) installing a base structure;
(ii) drilling a well through the base structure;
(iii) installing a casing string in the drilled well;
(iv) terminating the casing string with a wellhead;
(v) connecting a retrievable christmas tree module containing a christmas tree and fluid processing means to the wellhead by means of connecting means so as to receive well fluid therefrom; and
(vi) processing fluid received from the well via the wellhead and christmas tree with the processing means.

The method may also include employing any of the features referred to above.
The invention will now be described by way of example only with reference to the accompanying schematic figures in which:

Figure 1 shows a first system according to the present invention;
Figure 2 shows a second system according to the present invention; and
Figure 3 shows a third system according to the present invention.

In the Figures, like numerals are used to designate like parts and the description of a particular part applies to correspondingly numbered parts in different Figures unless otherwise stated.
A first system according to the invention is shown in Figure 1. A well string 2 emerges from the seabed 4 and terminates in a wellhead 6 Installed through a base structure 8 connected to the seabed 4. A retrievable module 10 containing a christmas tree 12 connected to a wellhead connector 14 is mounted on the base structure 8 by means of the wellhead connector 14 being coupled to the wellhead 6 and possibly by other engagement means not shown.
The retrievable module 10 also includes fluid processing means 15 including a minimum of two separators 16 which substantially duplicate each other thus affording component redundancy. The module could alternatively include only one set of processing means components. For the purpose of providing power and control to the module 10, and also transmitting signals therefrom, an electrical connector 18 is provided having first and second complementary interengageable portions 20 and 22 constituting parts of the module 10 and the base structure 8 respectively. An integrated service umbilical 24, for connection to a remote facility is connected to the second interengageable portion and a power and control pod 26 is connected to the first interengageable portion.
For the purpose of routing fluid(s) away from the module 10, a fluid connector 28 is provided including first and second complementary interengageable portions 30 and 32 constituting parts of the module 10 and the base structure 8 respectively. The second portion 32 being connected by one or more outlet pipes 34 to a flow line connection 36 which is in turn connected to one or more flow lines 38. Isolation valves 40 are incorporated in piping runs leading to the fluid connector 28 which can be closed when its first and second engageable portions are to be separated.
Fluid output from the christmas tree 12 to each separator 16 via separator input pipe 44 is controlled by two failsafe valves 42 and a choke valve 46. A gas output pipe 48 from each separator 16 routes gas through a pressure control valve 52. The gas output pipes 48 communicate with a gas passageway 56 of the first portion 30 of the fluid connector 28. A liquid output pipe 54 from each separator 16 routes liquid therefrom to a pump 50 and flow control valve 53 to a liquid passageway 58 in the first portion 30 of the fluid connector 28. Electrical signals from various sensors (not shown) are routed to the pod 26 which provides electrical signals for controlling the valves, the pumps, etc to control the operation of fluid processing means 15 and in particular the level of the gas/liquid interfaces in the separators 16. Signal/power lines between the components and the pod 26 have been omitted for the sake of clarity.
Figure 2 shows a second system according to the invention in which only one separator 16 is provided in the christmas tree module 60 rather than two. Liquid 62, gas 64, the liquid/gas interface 66 and interface level sensor 68 are shown in the separator 16 in Figure 2. These features have been omitted from Figure 1.
Figure 3 shows a third system according to the invention which differs from that shown in Figure 2 in that the fluid connector 28 and wellhead connector 14 of Figure 2 are replaced by a combined fluid connector and wellhead connector 70 including a first part 72 and a second part 74 comprising parts of the christmas tree module 76 and the base structure 78 respectively. Such a combined connector 70 could be employed in the system shown in Figure 1.
Such systems would also be suitable for other environments in which access poses a problem, for example in swampy areas.
The modules may form part of the modular system designed by Alpha Thames Limited of Essex, United Kingdom and named AlphaPRIME.

Claims

A single well development system comprising a base structure (8), a wellhead (6) completing a well, and a retrievable christmas tree module (10) including a christmas tree (12) and connecting means (14) for connecting the christmas tree module (10) to the wellhead (6) so as to receive well fluid therefrom, characterized in that:
the retrievable christmas tree module (10) includes fluid processing means (15) for processing fluid received from the well via the wellhead (6) and christmas tree (12); and

the base structure (8) has the well drilled through it.
The system as claimed in claim 1, wherein the christmas tree module (10) is primarily supported by means of its connection to the wellhead (6).
The system as claimed in claim 1 or 2, wherein the base structure (8) and/or the christmas tree module (10) include supplementary support means for the christmas tree module which is independent of the wellhead connecting means (14).
The system as claimed in any preceding claim, wherein the fluid processing means (15) in the module (10) comprises one or more separators (16).
The system as claimed in claim 4, including at least one flow control valve (52,53) for controlling the flow through at least one said separator (16).
The system as claimed in any preceding claim, wherein the retrievable christmas tree module (10) includes a power and/or control pod (26).
The system as claimed in claims 5 and 6, wherein the at least one flow control valve (53) is adjusted under control of said power and/or control pod (26).
The system as claimed in claim 6 or 7, including at least one electrical connector (18), the or each electrical connector comprising first and second interengageable portions (20,22), the first interengageable portion (20) forming part of said retrievable module (10) and the second interengageable portion (22) forming part of the base structure (8).
The system as claimed in claim 8, wherein the first interengageable portion (22) of the electrical connector (18) is connected to the power and/or control pod (26) in the module (10).
The system as claimed in claim 8 or 9, wherein the base structure second interengageable portion (22) of the electrical connector (18) is connected to an integrated service umbilical (24).
The system as claimed in claim 8, 9 or 10, wherein the connection means includes said electrical connector (18).
The system as claimed in any preceding claim, including at least one fluid connector (28), the or each fluid connector comprising first and second engageable portions (30,32), the first portion (30) forming part of said retrievable module (10) and the second portion (32) forming part of the base structure (8).
The system as daimed in claim 12, wherein the base structure based second engageable portion (32) of the fluid connector (28) is connected to a flow line connection (34,36) for conveying fluid from the base structure (8) to one or more external flow lines (38).
The system as claimed in claim 12 or 13, wherein the engageable portions (30,32) each include plural passageways for separate fluid flows and form part of the connecting means (14) for connecting the christmas tree (12) to the wellhead (6).
The system as claimed in claim 12, 13 or 14, wherein the connection means (70) includes said fluid connector for said module (76).
The system as claimed in any preceding claim, wherein the base structure (8) comprise a drilling template for drilling a well.
The system as claimed in any preceding claim, wherein the base structure (8) includes means for guiding the retrievable module (10) onto the base structure.
The system as claimed in any preceding claim, wherein the base structure (8) has means for supporting the retrievable module (10).
A method of exploiting the output from a single well, comprising the steps of:
(i) installing a base structure (8);

(ii) drilling a well through the base structure (8);

(iii) installing a casing string (2) in the drilled well;

(iv) terminating the casing string (2) with a wellhead (6);

(v) connecting a retrievable christmas tree module (10) containing a christmas tree (12) and fluid processing means (15) to the wellhead (6) by means of connecting means (14) so as to receive well fluid therefrom; and

(vi) processing fluid received from the well via the wellhead (6) and christmas tree (12) with the processing means (15).