WO2010136448A1

WO2010136448A1 - Sample bottle

Info

Publication number: WO2010136448A1
Application number: PCT/EP2010/057149
Authority: WO
Inventors: Gustav Wee
Original assignee: Gustav Wee
Priority date: 2009-05-27
Filing date: 2010-05-25
Publication date: 2010-12-02
Also published as: NO20092062L; NO330524B1

Abstract

Sample bottle, comprising a cylindrical sample chamber and a coaxial cylindrical displacement chamber, an axially movable piston sealingly separating said chambers, a feedthrough from the sample chamber to outside the sample bottle, a feedthrough from the displacement chamber to outside the sample bottle, and at least one end piece. The sample bottle is distinguished in that it comprises a mixing device, the mixing device is located in the sample chamber, the mixing device has the shape of a pipe section that closely fits into the sample chamber and it has end surfaces and a bore between said end surfaces, the piston and the end piece or sample bottle, on the sides facing the sample chamber, have shape and a protrusion coaxial to the mixing device bore, said shapes and protrusions are adapted to fit completely to the shape and bore of the mixing device, such that the mixing device is slideable in the sample chamber while providing mixing effect and the volume of the sample chamber can be reduced to contain only the mixing ring.

Description

Sample bottle

Field of the invention

The present invention relates to devices for taking representative samples of a fluid such as a well stream or a process stream. More specifically, the invention relates to a sample bottle.

Background of the invention and prior art

Devices for collecting samples are important for several industries, particularly the oil and gas industry. When for example the nature and size of a reservoir is to be determined, the further development of a field is to be determined or the efficiency of a process step is to be determined, the collection of samples can easily become crucial for the further steps to take. It is then natural to question the quality of the samples because decisions of huge technical and economical impact sometimes depend on the accuracy and representativeness of the collected samples.

For samples such as well stream samples, flashing or alteration of pressure, volume and temperature are not desirable. More specifically, the condition of the sample is to be maintained as constant as possible, to ensure that the sample is representative.

To this end, sample bottles containing a displacement fluid of similar pressure as the sample is useful. Before collecting the sample, a displacement chamber is filled with displacement fluid, such as glycol. A piston separates a sample chamber and the displacement chamber. When collecting the sample, the displacement fluid flows out of the displacement chamber while the sample flows into the sample chamber and the piston moves so as to displace the displacement fluid that is at a slightly lower pressure than the sample. Accordingly, the sample chamber is expanded and filled with the sample while the displacement chamber is retracted and the displacement fluid is discharged, without flashing or changing the sample properties significantly. A range of sample bottles operating according to the above mention principle can be provided by suppliers such as Proserv as, for more information see www.proserv.no However, the known sample bottles still result in samples for which the quality is questioned. The sample chamber typically contains a mixing ball somewhat smaller than the diameter of the typically circle cylindrical sample chamber. By manipulating the sample bottle or using magnets or other techniques, the mixing ball glides back and forth in the sample chamber, thereby providing mixing effect. But heavier constituents such as asphaltenes are prone to precipitate on the sample chamber wall, which represents a problem. A further problem with prior art technology is mixing of the fresh sample with small stagnant volumes of old sample fluid or flushing fluid remaining in the sample bottle when taking the sample. Choice of materials having different coefficients of expansion may also represent a problem. The objective of the present invention is to eliminate or reduce the above mentioned problems.

Summary of the invention

The objective is met by the present invention providing a sample bottle, comprising a cylindrical sample chamber and a coaxial cylindrical displacement chamber, an axially movable piston sealingly separating said chambers, a feedthrough from the sample chamber to outside the sample bottle, a feedthrough from the displacement chamber to outside the sample bottle, and at least one end piece. The sample bottle is distinguished in that it comprises a mixing device, the mixing device is located in the sample chamber, the mixing device has the shape of a pipe section that closely fits into the sample chamber and it has end surfaces and a bore between said end surfaces, the piston and the end piece or sample bottle, on the sides facing the sample chamber, have shape and a protrusion coaxial to the mixing device bore, said shapes and protrusions are adapted to fit completely to the shape and bore of the mixing device, such that the mixing device is slideable in the sample chamber while providing mixing effect and the volume of the sample chamber can be reduced to contain only the mixing device.

The sample bottle is in most embodiments cylindrical, such as built around a tube section, but not necessarily, since only the sample and displacement chambers must be cylindrical and coaxial in order to be divided between a movable piston. The cross- section shape of said cylindrical chambers is typically circular, but not necessarily, since also for example a square or elliptical cross section shape can be functional. For all embodiments with a rotation-symmetrical cross section shape, the bore and protrusions as referred to above are all coaxial with the longitudinal centre axis of the chambers, for other cross-section shapes said bore and protrusions must be aligned but not necessarily coaxial to the axis of the sample bottle or chambers. Further, the sample bottle comprises at least one end piece, since one end can be solid or integral with the outer wall, such as a sample bottle machined from a bolt from one end. But preferably there are two end pieces, such as one end cap in each end.

Preferably the sample bottle according to the invention includes a mixing device in the form of a mixing ring having concave end surfaces and a central bore. Preferably the mixing ring includes a knife-like edge on each end, at the periphery, scraping off heavier constituents from the sample chamber wall while mixing in order to thoroughly mix also said heavier constituents in the sample. The mixing device or mixing ring closely fits into the sample chamber, which in this context means that it scrapes off heavier constituents and any other deposits from the wall of the sample chamber during mixing, ensuring that such scraped off constituents are mixed thoroughly in the sample, thereby ensuring that the sample is representative.

Preferably the length of the protrusions in sum equals the length of the bore through the mixing device. This, together with end surface shapes of the mixing device matching the end surface shapes of the sample chamber, ensures that the sample chamber volume can be reduced to contain only the mixing device, thereby eliminating small stagnant volumes in the sample chamber containing fluid that can mix with a fresh sample. The expression "the piston and the end piece or sample bottle, on the sides facing the sample chamber" means the end surfaces of the sample chamber. More specifically, the shape of the respective end surfaces of the sample chamber completely matches the shape of the respective end surfaces of the mixing device, and the protrusions can in sum completely fill out the bore of the mixing device. Preferably all parts except seals and packers are made of materials having identical properties with respect to thermal and other elastic expansion, such as titanium grade 5 or 2. Alloys such as "super duplex" (e.g SAF 2507), 6 Mo and several other stainless steel alloys and alloys having high contents of nickel, can all be useful. However, expansion and elastic properties are important factors to take into consideration in order to ensure favourable technical effect in a given operating range of conditions. Preferably, the mixing device and the outside part, such as an outside pipe section, are made of identical materials or are designed in order to have equal properties in such respect.

Preferably the sample bottle includes two replaceable threaded end caps including feedthrougs (through bores, fluid passageways) and instrumentation or transmitters, such as for pressure, temperature, volume and time. A logger, documenting the PVT history of a sample, can preferably be included. In order to facilitate replacement and installation, sensors, loggers and other types of instrumentation are preferably integrated in or have connection to the end cap facing the sample chamber.

The sample bottle preferably comprises two feedthroughs from the sample chamber to outside the sample bottle, preferably in an end cap and preferably the feedthroughs converge at the sample chamber in order to allow complete flushing of the sample chamber and feedhtrough fluid passageways before taking a representative sample. Small stagnant volumes of old fluid in the inlet port fluid passageway (feedthrough) will thereby not mix with the fresh sample. One of said feedthroughs can be a fluid passageway for bleeding out fluid or it can include means such as threaded ports, valves, connectors etc. for being connected to a process return line, returning the flushing fluid to a process location having appropriate process conditions.

The sample bottle preferably comprises a heater, and a thermostat control, in order to preheat the sample bottle before sample collection and maintaining a constant temperature while the sample bottle contains a sample. The heater can be arranged under a thermo insulation layer. The most preferable embodiment of the sample bottle according to the invention includes all of the above mention features, however, different embodiments may include different features as here described in any combination.

Figure

The sample bottle of the invention is illustrated in Figure 1.

Detailed description

Reference is made to figure 1, illustrating an embodiment of a sample bottle according to the present invention. More specifically, a sample bottle 1 is illustrated, comprising a cylindrical sample chamber 2 and a coaxial cylindrical displacement chamber 3, an axially movable piston 4 sealingly separating said chambers, a feedthrough 5 from the sample chamber to outside the sample bottle, a feedthrough 6 from the displacement chamber to outside the sample bottle, one end piece 7 in the form of a replaceable threaded end cap closing the sample chamber and one end piece 8 in the form of a replaceable threaded end cap closing the displacement chamber. The end pieces 7, 8 can be screwed into internal threads on a pipe section 9 that makes up the largest part of the sample bottle 1. Further, the sample bottle comprises a mixing device 10 in the form of a mixing ring, the mixing device is located in the sample chamber 2, the mixing device has the shape of a pipe section that closely fit into the sample chamber and it has concave end surfaces 10a and 10b and a central bore 10c between said end surfaces. Further, the piston 4 and the end piece 7 closing the sample chamber, on the sides 4a, 7a facing the sample chamber, respectively, have convex shape and a central protrusion, 7b and 4b respectively, the protrusions are coaxial to the mixing device bore, and said shapes and protrusions are adapted to fit completely to the end surface shapes and bore of the mixing device 10. Further, a spiral groove 11 on the displacement chamber side of the piston is illustrated, which groove prevents vacuum. Also, conventional seals and packers are illustrated.

Accordingly, the mixing device is slideable in the sample chamber while providing mixing effect and the volume of the sample chamber can be reduced to contain only the mixing ring. More specifically, heavier constituents are scraped off by the mixing device as it slides or glides in close contact with the inner wall of the sample chamber, while said constituents are mixed thoroughly in the sample since the flow through the bore generates agitation and mixing effect. Also, the existence of small stagnant volumes of old fluid in the sample chamber is avoided by the design as described above, by matching shapes of surfaces and bores and protrusions as good as possible in order to be able to eliminate all dead volumes. In addition to use topsides, the sample bottle can be adapted for use downhole by incorporating appropriate prior art technology.

Testing has surprisingly revealed that the sample bottle of the invention, in addition to meeting the objective as set forth, also results in a significantly reduced period of time for mixing, typically 30 % or even 50 % reduction. Without any desire to be bound by theory, it is assumed that the favourable technical effect of the sample bottle of the invention also is due to the fact that the flow of fluid during mixing is far more turbulent than for prior art sample bottles.

Claims

C l a i m s 1.

Sample bottle (1), comprising a cylindrical sample chamber (2) and a coaxial cylindrical displacement chamber (3), an axially movable piston (4) sealingly separating said chambers, a feedthrough (5) from the sample chamber to outside the sample bottle, a feedthrough (6) from the displacement chamber to outside the sample bottle, and at least one end piece (7,8), characterised in that the sample bottle comprises a mixing device (10), the mixing device is located in the sample chamber (2), the mixing device has the shape of a pipe section that closely fits into the sample chamber and it has end surfaces (10a, 10b) and a bore (10c) between said end surfaces, the piston (4) and the end piece (7) or sample bottle, on the sides facing the sample chamber (2), have shape (4a,7a) and a protrusion (4b,7b) coaxial to the mixing device bore, said shapes and protrusions are adapted to fit completely to the shape and bore of the mixing device, such that the mixing device (10) is slideable in the sample chamber (2) while providing mixing effect and the volume of the sample chamber can be reduced to contain only the mixing device.

2.

Sample bottle according to claim 1, characterised in that the mixing device (10) is a mixing ring having concave end surfaces (10a, 10b) and a central bore (10c).

3.

Sample bottle according to claim 2, characterised in that the mixing ring includes a knife-like edge on each end, at the periphery, scraping off heavier constituents from the sample chamber wall while mixing in order to thoroughly mix also said heavier constituents in the sample.

4.

Sample bottle according to claim 1, characterised in that the length of the protrusions (4b,7b) in sum equals the length of the bore (10c) through the mixing device.

5.

Sample bottle according to claim 1, characterised in that all parts except seals and packers are made of titanium.

6.

Sample bottle according to claim 1, characterised in that it includes at least one end piece in the form of two replaceable threaded end caps (7,8).

7. Sample bottle according to claim 1, characterised in that it comprises two feedthroughs from the sample chamber to outside the sample bottle, in order to allow complete flushing of the sample chamber and feedhtrough fluid passageways.

8. Sample bottle according to claim 1, characterised in that it comprises a heater, and a thermostat control, in order to preheat the sample bottle before sample collection and maintaining a constant temperature while the sample bottle contains a sample.