WO2010144945A1

WO2010144945A1 - Remote installation of seabed instrument package

Info

Publication number: WO2010144945A1
Application number: PCT/AU2010/000671
Authority: WO
Inventors: Patrick Joseph Kelleher; Stephen David Payor
Original assignee: Benthic Geotech Pty Ltd
Priority date: 2009-06-15
Filing date: 2010-06-01
Publication date: 2010-12-23

Abstract

A standpipe assembly for remote installation of in situ seabed monitoring, sensing or measuring devices. The standpipe assembly including, a plurality of individual sections (1) coupled together, a lower rod adaptor (3) attached to or integrated with a measuring device (4), and an upper rod adaptor (5) adapted to separately couple to an auxiliary tubular extension (13), a closure cap (6) and an instrument package (7). The measuring device (4) can communicate with the instrument package (7). Also disclosed is a method of installing the standpipe assembly, including connecting individual sections 1 to a downward thrusting apparatus, and connecting the auxiliary tubular extension (13) associated with the upper rod adaptor (5) to the same part of the downward thrusting apparatus, and then removing the auxiliary tubular extension (13) to connect an upper section or end (8) of the upper rod adaptor (5) to the instrument package (7).

Description

Remote Installation of Seabed Instrument Package

Technical Field

[001] The present invention generally relates to an apparatus, assembly and/or method for remote installation of in situ seabed monitoring, sensing or measuring devices for geotechnical applications.

Background

[002] In many aspects of offshore technologies there is a need to monitor in situ parameters of seabed soil formations, particularly in the identification and study of geohazards arising from potentially unstable slopes and sediments. An example of such monitoring is the well recognised importance of knowing the pore pressure regimes to provide a fundamental understanding of soil strength and stability behaviour.

[003] Presently, a known technique for gathering in situ soil data, including pore water pressure measurements, involves probing the seabed using standard piezocone penetrometer instruments deployed from floating vessels, surface platforms, seabed rigs or ROV (Remotely Operated Vehicle) equipment. However, the practicalities and high costs of operating such equipment mean pore pressure dissipation tests conducted using this method are necessarily of relatively short duration (typically a few hours), whereas it is desirable to acquire such data over much longer periods of weeks or months.

[004] A number of methods have been described for in situ measurement and long term monitoring of pore pressure (see for example, J.M. Strout & T.I. Tjelta, 2007 Offshore Technology Conference, Paper 18706: 'Excess Pore Pressure Measurement and Monitoring for Offshore Instability Problems'). These methods involve various installation approaches, including piezometer lances that may be ballasted free-fall or hammered-in, wire-line installations in drilled geotechnical boreholes, hydraulic standpipes installed by seabed frame or coiled tube apparatus.

[005] There are several disadvantages associated with this conventional equipment and techniques, for example: limited penetration depth of just a few metres below mudline; imprecise or indeterminate penetration depth; indeterminate height of termination of the standpipe above the mudline; inability of the seabed frame for self-levelling to ensure vertical alignment of the standpipe; limitations of geotechnical drilling vessels to establish bore holes in deepwater locations (typically > 1000 m).

[006] There is a need for an apparatus, assembly and/or method for installation of in situ seabed monitoring, sensing or measuring devices which addresses or at least ameliorates one or more problems inherent in the prior art.

[007] The reference in this specification to any prior publication (or information derived from the prior publication), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from the prior publication) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Brief Summary

[008] In one aspect, the present invention provides an apparatus, assembly and/or method for installation of a seabed instrument package or probe using a seabed drill or thrusting apparatus.

[009] In another aspect, the present invention provides deepwater installation capability, precise positioning at predetermined depths below the mudline, controlled termination height above the mudline, and/or vertical alignment of seabed monitoring, sensing or measuring devices.

[010] In another aspect, the present invention provides connection means that permit a variety of in situ sensor, probes or measuring devices to be deployed into the seabed and a variety of instrument package configurations to be located at the seafioor such that they are accessible for installation and data retrieval.

[01 1] According to a particular example form, there is provided a standpipe assembly for deployment of a measuring device into a seabed, including: a plurality of individual sections; an instrument probe including or attachable to the measuring device, the instrument probe adapted to be coupled to a first individual section; an upper section adapted to couple to a last individual section, the upper section removably attachable to an auxiliary extension.

[012] According to a further example form, there is provided a standpipe assembly for deployment of a measuring device into a seabed, including: a plurality of individual sections adapted to be coupled together, including a first individual section near a lower end of the standpipe when in position in the seabed, and a last individual section near an upper end of the standpipe when in position in the seabed; an instrument probe including the measuring device, the instrument probe adapted to be coupled to the first individual section; an upper section adapted to couple to the last individual section, the upper section including an upper end or portion which is removably attachable to an auxiliary extension which can be gripped by downward thrusting apparatus.

[013] Preferably, the auxiliary extension is an auxiliary tubular extension. In another form, the upper end is also removably attachable to a closure cap. In another form, the upper end is also removably attachable to an instrument package.

[014] According to a further example form, there is provided a standpipe assembly for deployment of a measuring device into a seabed, including: a plurality of individual sections coupled together; a lower rod adaptor attached to a first individual section, the lower rod adaptor including or attached to the measuring device; and, an upper rod adaptor attached to a last individual section, the upper rod adaptor attached to an instrument package able to communicate with the measuring device.

[015] According to a further example form, there is provided an apparatus for deployment of a measuring device into a seabed, the apparatus used with a plurality of individual sections able to be coupled together to form a standpipe when positioned in the seabed by using a downward thrusting apparatus located on the seabed, the apparatus including: a lower rod adaptor including or attachable to the measuring device, the lower rod adaptor able to be coupled to a first individual section; and, an upper rod adaptor able to be coupled to a last individual section, the upper rod adaptor also removably attachable to an auxiliary extension which in use can be gripped by the downward thrusting apparatus. [016] According to a further example form, there is provided a method of installing a standpipe assembly in a seabed, including the steps of: attaching a lower rod adaptor, having an attached or integrated measuring device, to a first individual section; attaching a series of individual sections to the first individual section using a downward thrusting apparatus; attaching an upper rod adaptor to a last individual section, the upper rod adaptor including an upper portion; attaching an auxiliary extension to the upper rod adaptor so that the upper portion of the upper rod adaptor is received internally to the auxiliary extension; attaching at least the auxiliary extension to the downward thrusting apparatus so as to position the measuring device at a desired depth; and, removing the auxiliary extension to leave the upper portion of the upper rod adaptor above the seabed.

Brief Description of Figures

[017] Example embodiments should become apparent from the following description, which is given by way of example only, of at least one preferred but non-limiting embodiment, described in connection with the accompanying figures.

[018] Fig. 1 illustrates an example standpipe configuration.

[019] Fig. 2 illustrates an example of a piezometer drill string configuration.

Preferred Embodiments

[020] The following modes, given by way of example only, are described in order to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments.

[021] Referring to Fig. 1, there is illustrated a standpipe assembly or apparatus 10 for deployment of a measuring device into a seabed below a mudline. The standpipe assembly includes a plurality of individual sections 1 adapted to be coupled together to form a drill string. Individual sections 1 include a first individual section Ia near a lower end of the standpipe when in position in the seabed, and a last individual section Ib near an upper end of the standpipe when in position in the seabed. An instrument probe (i.e. lower rod adaptor) 3 includes, or is otherwise attached to, measuring device 4, which can be selected from a variety of different measuring devices. Lower rod adaptor 3 is adapted to be coupled to the first individual section Ia. Upper section (i.e. upper rod adaptor) 5 is adapted to couple to the last individual section Ib, and upper rod adaptor 5 includes an upper end, section or portion 8 which is removably attachable to an auxiliary extension 13 (see Fig. 2) which can be gripped by downward thrusting apparatus (for example a seabed drill) in a similar manner as when gripping and forcing individual sections 1 downward into the seabed.

[022] Instrumentation standpipe assembly 10, includes individual sections 1, preferably of tubular material of set length, that can be advanced into a soil formation by the downward thrusting apparatus or seabed drill, where further individual sections 1 are progressively added until the desired penetration depth is achieved. Adjoining individual sections 1, for example of tubular material, are sealed by a fluid-tight coupling 2, such that the complete standpipe is continuously sealed along its length. The fluid-tight coupling 2 can be provided in a variety of forms, for example an o-ring 2a held in a groove provided in a drill rod pin and box joint.

[023] The first individual section Ia of tubular material near the lower end of the standpipe is adapted to attach an in situ sub-probe or lower rod adaptor 3, which includes or attaches to at least one measuring device 4, for example a piezometer filter element, geophone or other type of sensing, monitoring, measuring or sampling device. Optionally, though not necessarily, the overall length of lower rod adaptor 3 and measuring device 4 matches the set length of the individual sections 1 of the standpipe 10.

[024] The last individual section Ib of tubular material near the top or upper end of the standpipe 10 is adapted to attach an upper rod adaptor 5 in a fluid-tight connection. Upper rod adaptor 5 has an upper end, section or portion 8 able to separately attach to an auxiliary extension 13, a closure cap 6 and a particular type of instrument pack 7. Optionally, though not necessarily, the overall length of the upper rod adaptor 5 matches the set length of the individual sections 1 of the standpipe 10. A variety of attachment mechanisms for securing the auxiliary extension 13, the closure cap 6 or the instrument package 7 to upper end 8 of the upper rod adaptor 5 can be provided, such as a tapered spigot, threaded assembly, locking pin, lock ring, push-on seal, bayonet fitting or the like.

[025] In the process of installing the standpipe, should the soil strength exceed the capacity of the direct downward thrusting apparatus to advance the standpipe assembly into the soil formation, the lower end of the standpipe, or first individual section Ia, may be adapted to attach a drill bit, which by mechanical rotation and cuttings removal by fluid circulation, allows the standpipe assembly to be advanced into the soil to the desired depth.

[026] Where adverse soil conditions may create difficulty in advancing the instrumentation standpipe, an alternative means of installation may be provided by establishing a borehole with casing pipe sections advanced into the soil formation by downward thrusting, rotation and wash boring to a desired depth, and subsequently advancing the standpipe inside the casing. A grouting plug may be introduced to seal the gap between the inner standpipe and the outer casing. For example, the grouting plug material may be pre-loaded in rupturable packaging into a special tube assembly at a preselected distance behind the instrument probe 3, and activated by drill water pressure at an appropriate time.

[027] By this arrangement the standpipe can be formed to a desired depth D of sub- seabed penetration, based on a multiple of the set length of the individual sections 1 of tubular material, typically, for example, to a maximum of about 100 metres below the mudline, and terminating at a desired height H, typically, for example, about 0.5 to 1 metre, above the mudline, to suit a particular instrument package 7 configuration and installation method. The standpipe can accept various configurations of in situ devices, smaller or equal in diameter to the standpipe, or outer casing if used, and can accept various configurations or types of instrument package 7.

[028] Coupling and thrusting the standpipe sections may be provided by a remotely operated seabed drill unit. Example units include the Seafloor Geoservices ROV Drill

M80, the Williamson & Associates DWACS (Deepsea Wireline Automated Coring

System), the University of Bremen MeBo Sea Floor Drill Rig and the Benthic Geotech

PROD (Portable Remotely Operated Drill). These known devices may be adapted to contain the tubular standpipe individual sections 1 in their tool magazines as well as the lower rod adaptor 3, for example already coupled to measuring device 4, and the upper rod adaptor 5 specially adapted to attach to the instrument package 7.

[029] In one aspect, the present invention facilitates handling of a last section of standpipe which in other methods may be significantly smaller in diameter than the other individual sections 1 of the standpipe and would otherwise be impossible to hold in a drill unit chuck for a final downward advancement stroke. An externally-threaded shoulder is provided as part of upper end 8 of upper rod adaptor 5 at a suitable distance below the terminating spigot or attachment device. This allows an auxiliary extension 13, which is preferably tubular, of the same or similar diameter as the individual sections 1 to be fitted prior to loading the tool magazine. The overall length of upper rod adaptor 5 and auxiliary extension 13 preferably matches the overall combined length of lower rod adaptor 3, measuring device 4 and the set length of an individual section Ia of the standpipe.

[030] By this arrangement the upper rod adaptor 5 can be gripped in a normal manner by a drill chuck and rod clamps for completing the standpipe to its final depth, then while gripping the standpipe in the rod clamp, the auxiliary extension 13 can be unscrewed by rotation of the drill head and lifted off, leaving the standpipe termination, being part of upper rod adaptor 5, correctly positioned or configured to receive instrument package 7 or closure cap 6.

[031] Certain types of instrumentation such as a piezometer require only a hydraulic connection between the measuring device 4 at the lower end of the standpipe and the measurement and data logging instrument package 7 mounted above the mudline at the upper end of the standpipe. In this case a water column in the continuously sealed standpipe 10 serves as the connection means or transmission medium. Other types of instrumentation, for example a geophone, may require connection means of physical wires or cables between the down-hole measuring device 4 and the data logging instrument package 7 mounted above the mudline at the upper end of the standpipe. For some instrument probes, a wireless electromagnetic or acoustic signal can be suitable as the connection means.

[032] Installation of the instrument package 7 may be achieved by common intervention methods such as using a ROV with suitable tools to remove or replace the preinstalled cap 6 from the standpipe, fit or remove the instrument package 7 on the standpipe, and periodically interrogate the data logger and recharge instrument package batteries.

[033] A further aspect of the present invention therefore provides for remotely connecting the down-hole measuring device 4 to the data logging instrument package 7. In one form, the connection means includes a reeled cable assembly that can be positioned over the upper open end of the standpipe using an ROV or similar remotely operated equipment, such that the free end of the cable may be lowered to reach the down-hole measuring device 4 while the other fixed end is connected to the instrument package 7.

[034] The cable may comprise electrical or optical conductors, or a combination thereof, terminated at the free end with a weighted assembly. This cable termination assembly and a down-hole measuring device assembly are adapted to provide a mating connection 9, whereby power may be fed to the measuring device 4 and data signals may be exchanged between the measuring device 4 and the remote instrument package 7. The method of power and data exchange providing connection means may be via an electrical or electro- optical stab connector or via a close proximity wireless link employing inductive coupling, optical, infrared, or radiofrequency devices. The mating connector faces can be configured to mechanically guide the mating halves of the assemblies together and may be locked in place with the use of magnets embedded in the connector faces.

Further Examples

[035] The following examples provide a more detailed discussion of particular embodiments. The examples are intended to be merely illustrative and not limiting to the scope of the present invention.

[036] Referring to Fig. 2, there is illustrated an example embodiment of the present invention for a hydraulic piezometer configuration. A first tool assembly A is located at the bottom of the standpipe, first tool assembly A comprising drill rod 1 a of a standard length Ll, hydraulic piezometer probe 4 and lower rod adaptor 3. Piezometer probe 4 is a known device, characterised by a cylindrical porous filter element, smaller in diameter (typically 30-40mm) than lower rod adaptor 3 (typically 60mm diameter). The length of lower rod adaptor 3 is specified in accordance with the length of piezometer probe 4 such that the overall length of tool assembly A is a set maximum length L2 (typically 3m) to suit the tool magazine of a remotely operated seabed drill rig.

[037] A second tool assembly B is located at the top of the standpipe, second tool assembly B comprising upper rod adaptor 5 removably connected to hydraulic stab adaptor 12. An externally threaded shoulder 11 is provided on upper rod adaptor 5 for removably connecting to a corresponding internal thread provided as part of auxiliary tubular extension 13. The overall length of second tool assembly B matches the set length L2 of first tool assembly A. Auxiliary tubular extension 13 has the same external diameter (typically 60mm) as upper rod adaptor 5 and individual tubular sections 1 that comprise the main section of standpipe between first tool assembly A and second tool assembly B.

[038] The method of installation of the piezometer hydraulic standpipe comprises the following sequence of steps by way of example.

[039] Prior to launch of the remotely operated seabed drill rig:

(a) Piezometer 4, lower rod adaptor 3 and drill rod Ia are assembled as first tool assembly A, preferably using a thread sealant compound on the joints to ensure an adequate hydraulic seal is achieved between these components.

(b) Hydraulic stab 12 and upper rod adaptor 5 are assembled, again preferably using a thread sealant compound on the joint to achieve a hydraulic seal.

(c) Auxiliary tubular extension 13 is assembled onto upper rod adaptor 5 as second tool assembly B.

(d) Individual tubular sections 1 are fitted with o-ring seals and preferably lightly greased (e) Tool assemblies A and B and individual tubular sections 1 sufficient to reach target depth D below the mudline are loaded into the tool magazines of the seabed drill rig.

[040] When the seabed drill rig is positioned on the seabed: (f) For shallow boreholes in soft seabed formations first tool assembly A is pushed into the seabed with sufficient individual tubular sections 1 added behind first tool assembly A until target depth D is approximately achieved.

(g) For deeper boreholes, where excessive frictional force may prevent continuous pushing to target depth D, a borehole is established by rotary drilling and terminated approximately within a drill rod length of the target depth D. The drill string is withdrawn and reinstalled in the borehole with first tool assembly A substituted for the rotary drilling tool.

(h) Second tool assembly B is then attached at the upper end of the drill string and the drill string is pushed downwards a short further distance into undisturbed soil, until upper rod adaptor 5 aligns with the drill rig lower clamp and the upper end of hydraulic stab 12 is positioned at predetermined height H above the mudline.

(i) With upper rod adaptor 5 gripped by the drill rig clamp, auxiliary tubular extension 13 is unscrewed from upper rod adaptor 5 using the drill rig rotary chuck and returned to the tool magazine.

(j) The seabed drill rig is lifted clear of exposed hydraulic stab 12 and recovered to the launch vessel, leaving hydraulic standpipe assembly 10 ready for installation of instrument package 7 using suitable ROV equipment. (k) Instrument package 7, or closure cap 6, can be fitted to exposed hydraulic stab 12, whilst it is known that piezometer 4 is correctly positioned at the target depth D.

[041] Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[042] Although a preferred embodiment has been described in detail, it should be understood that various changes, substitutions, and alterations can be made by one of ordinary skill in the art without departing from the scope of the present invention.

Claims

The claims:

1. A standpipe assembly for deployment of a measuring device into a seabed, including: a plurality of individual sections coupled together; a lower rod adaptor attached to a first individual section, the lower rod adaptor including or attached to the measuring device; and, an upper rod adaptor attached to a last individual section, the upper rod adaptor attached to an instrument package able to communicate with the measuring device.

2. The standpipe assembly as claimed in claim 1, wherein the lower rod adaptor is substantially the same outer diameter as the individual sections.

3. The standpipe assembly as claimed in either claim 1 or 2, wherein the upper rod adaptor is substantially the same outer diameter as the individual sections.

4. The standpipe assembly as claimed in any one of claims 1 to 3, wherein the upper rod adaptor is separately attachable to an auxiliary extension, the instrument package and a closure cap.

5. The standpipe assembly as claimed in any one of claims 1 to 4, wherein the upper rod adaptor includes an upper portion that after insertion of the standpipe into the seabed is positioned at a selected height above the seabed after the auxiliary extension is removed.

6. The standpipe assembly as claimed in any one of claims 1 to 5, wherein the upper portion of the upper rod adaptor is of smaller outer diameter than the individual sections.

7. The standpipe assembly as claimed in any one of claims 1 to 6, wherein the auxiliary extension when attached to the upper rod adaptor can be gripped by a downward thrusting apparatus.

8. The standpipe assembly as claimed in any one of claims 1 to 7, wherein the auxiliary extension is substantially the same outer diameter as the individual sections.

9. The standpipe assembly as claimed in any one of claims 1 to 8, wherein the upper rod adaptor includes a hydraulic stab.

10. The standpipe assembly as claimed in any one of claims 1 to 9, wherein the lower rod adaptor, the upper rod adaptor and the auxiliary extension are of tubular extent.

11. The standpipe assembly as claimed in any one of claims 1 to 10, wherein the standpipe assembly is substantially fluid tight and the measuring device is a piezometer in fluid connection with the measuring device.

12. The standpipe assembly as claimed in any one of claims 1 to 11, wherein when attached, the combined length of the lower rod adaptor, the measuring device and the first individual section is substantially equal to the combined length of the upper rod adaptor and the auxiliary extension.

13. An apparatus for deployment of a measuring device into a seabed, the apparatus used with a plurality of individual sections able to be coupled together to form a standpipe when positioned in the seabed by using a downward thrusting apparatus located on the seabed, the apparatus including: a lower rod adaptor including or attachable to the measuring device, the lower rod adaptor able to be coupled to a first individual section; and, an upper rod adaptor able to be coupled to a last individual section, the upper rod adaptor also removably attachable to an auxiliary extension which in use can be gripped by the downward thrusting apparatus.

14. The apparatus as claimed in claim 13, wherein the auxiliary extension is an auxiliary tubular extension.

15. The apparatus as claimed in either claim 13 or 14, wherein the upper rod adaptor includes an upper portion able to be received internally within the auxiliary extension.

16. The apparatus as claimed in any one of claims 13 to 15, wherein the upper rod adaptor is also removably attachable to a closure cap.

17. The apparatus as claimed in any one of claims 13 to 16, wherein the upper rod adaptor is also removably attachable to an instrument package.

18. The apparatus as claimed in any one of claims 13 to 17, wherein the individual sections, the lower rod adaptor and the upper rod adaptor are positioned in one or more tool magazines of a remotely operated seabed drill unit.

19. A method of installing a standpipe assembly in a seabed, including the steps of: attaching a lower rod adaptor, having an attached or integrated measuring device, to a first individual section; attaching a series of individual sections to the first individual section using a downward thrusting apparatus; attaching an upper rod adaptor to a last individual section, the upper rod adaptor including an upper portion; attaching an auxiliary extension to the upper rod adaptor so that the upper portion of the upper rod adaptor is received internally to the auxiliary extension; attaching at least the auxiliary extension to the downward thrusting apparatus so as to position the measuring device at a desired depth; and, removing the auxiliary extension to leave the upper portion of the upper rod adaptor above the seabed.

20. The method as claimed in claim 19, including: attaching either an instrument package or a closure cap to the upper portion of the upper rod adaptor.

21. The method as claimed in either claim 19 or 20, including: assembling the lower rod adaptor, the measuring device and the first individual section as a first tool assembly and storing the first tool assembly in a magazine of a remotely operated seabed drill unit.

22. The method as claimed in any one of claims 19 to 21, including: assembling the upper rod adaptor and the auxiliary extension as a second tool assembly and storing the second tool assembly in a magazine of a remotely operated seabed drill unit.