KUWAHARA SHIGEFUMI (JP)
MIYAZAWA TERUO (JP)
KUWAHARA SHIGEFUMI (JP)
| JP2001288079A | 2001-10-16 | |||
| JP2000290178A | 2000-10-17 | |||
| JP2000281572A | 2000-10-10 | |||
| JPH054963A | 1993-01-14 |
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WISE M L ET AL: "Biosynthesis of conjugated triene-containing fatty acids by a novel isomerase from the red marine alga ptilota falicina", BIOCHEMISTRY, vol. 33, no. 51, 1994, pages 15223 - 15232, XP000943620
SOLEM M L ET AL: "Three new and bioactive icosanoids from the temperate red marine alga farlowia mollis", LIPIDS, vol. 24, no. 4, 1989, pages 256 - 260, XP002904243
LOPEZ A ET AL: "Two new icosapentaenoic acids from the tepmerate red seaweed ptilota filicina j. agardh", LIPIDS, vol. 22, no. 3, 1987, pages 190 - 194, XP002904244
| 1. | An appar.; ;s for testing concrete/cement mixtures intended for use with cementing of casings within subsea bore holes for oil and/or gas wells, wherein cement mixture/ concrete sample during at least a part of the test, i.a. until hardening occurs, is accommodated within a cavity which may be formed by the interior of a preferably tubular test container (6), c h a r a c t e r i z e d i n that the test apparatus comprises or is connected to, respectively, means for the establishment and for the measuring of temperature and pressure conditions which at least partly correspond to those conditions anticipated to appear at the subsea casing cementing place concerned. |
| 2. | An apparatus as set forth in claim 1, c h a r a c t e r i z e d i n that the apparatus comprises a chamber (1,1') formed with a cavity for the accommodation of a tubular test container (6); heating/ cooling means (5) arranged within said cavity and at least partly defining that part of the cavity which serves for the accommodation of the tubular test container (6), wherein the chamber/test container (l,l'/6) is provided with inlet (16') for supply of gas to the interior of the test container (6), in order to establish first pressure conditions which substantially may correspond to those conditions which are anticipated to appear in the bore hole at the place of application, for the concrete/cement mixture, and that the chamber/test container (l,l'/6) is provided with outlet (18,18') for special supply of gas, in order to create a differential pressure which substantially may be considered ro simulate e.g. that extra pressure which is caused by a leakage of gas in the reservoir wherein the tested concrete/ cement mixture is intended to be used; the apparatus being equipped with or connected to, respectively, measuring instrument means for the measuring of at least the following parametres during the test: the temperature of the concrete/ cement mixture; amount of gas into/out from, respectively, the cement mixture/concrete sample; main pressure (i.e. the pressure prevailing during the abovementioned first pressure conditions) and possibly differential pressure. |
| 3. | An apparatus as set forth in claim 2, c h a r a c t e r i z e d i n that the pipelike test container (6) is equipped internally with measuring means, preferably in the form of a load cell (15), for measuring the hydrostatic pressure to which the cement mixture/ concrete samle is subjected during the test. |
| 4. | An apparatus as set forth in claim 1, 2 or 3, c h a r a c t e r i z e d i n that said heating/cooling means consists of a number of axially extending pipes (5) arranged peripherically within the cavity of the chamber (1,1'), said pipes (5) carrying heat/cold medium, and that the central portion of said cavity, radially defined inwardly of the pipes (5), is reserved for the accommodation of the pipelike test container (6). |
| 5. | An apparatus as set forth in one or more of the claims 14, c h a r a c t e r i z e d i n that the chamber consists of two interhinged (2) cylindrical halves (1,1' ) which, thus, may be rotated in order to open and close the chamber, thereby securing a simple removal of the test container (6) after the various measurements within the test apparatus have been carried through. |
| 6. | An apparatus as set forth in one or more of the claims T5, c h a r a c t e r i z e d i n that the pipelike test container (6), the main body thereof consisting of a tight pipe wall, is provided with end caps (14,14' ) at each end thereof, and that one end cap (14) has two through going bores each associated with a supply conduit (16,16' ), one (16) for the supply of gas for the establishment of desired pressure conditions and possibly migration through the concrete sample, one for the supply and possibly circulation of cement mixture/drilling fluid/separating liquid, and that the other end cap (14') is formed with two outlets (17,17'), one (17) for gas and one for circulated cement mixture/drilling fluid/separating liquid, the outlet (17) for gas being coupled to a measuring instrument for the measuring of the amount of gas that might have migrated through the concrete sample. |
| 7. | An apparatus as set forth in any one of the preceding claims, c h a r a c t e r i z e d i n that the chamber (1,1') is pivotally arranged around a lateral horizontal axis, so that the chamber (1,1') together with the pipe¬ like test container (6) may be adjusted to a position extending slopingly or perpendicularly to the vertical plane, in order to simulate cementing conditions for casings within deviated wells or horizontal wells, respectively. |
| 8. | An apparatus as set forth in any one of the preceding claims , c h a r a c t e r i z e d i n that the chamber/ test container (l,l'/6) is provided with means (18, 18 ',19) for the supply and distribution of gas, establishing a differential pressure. |
| 9. | An apparatus as set forth in claim 1, 2 and 5, c h a r a c t e r i z e d i n that the hinged semi cylindrical chamber halves (1,1' ) are formed with a double wall, the spacing thereof being filled with a thermal insulating material (3). |
| 10. | A method for testing concrete/cement mixtures intended for use when cementing casings within subsea bore holes for oil and/or gas wells, wherein the cement mixture/concrete sample is placed within a cavity, preferably formed by a pipelike test container (6), during at least a part of the test , c h a r a c t e r i z e d i n that temperature and pressure conditions are established and measured, at least partly corresponding to those conditions anticipated to appear at the subsea casing cementing location. |
| 11. | A method as set forth in claim 10, c h a r a c t e r i z e d i n that the cement mixture is circulated, preferably through a pipelike test container (6), which is filled with cement mixture prior to the start of the actual test, the level of the cement mixture within the test container being adjusted such that a certain distance from the upper end of the test container is established, whereafter the test container (6) is put under a pressure substantially simulating the general pressure conditions at the intentional place of application for the cement mixture, namely through conducting gas in above and below the cement mixture sample, whereafter a differential pressure is established through conducting gas in radially in relation to the longitudinal axis of the pipelike test container ( 6 ) , the cement mixture sample being heated or cooled, respectively, during the test in order to simulate the temperature conditions at the intentional place of application for the cement mixture. |
| 12. | A method as set forth in claim 10 or 11, c h a r a c, t e r i z e d i n that prior to the pumping of cement mixture into the pipelike test container drill fluid and thereafter separating fluid is pumped into the test container (6), and that said fluids may be circulated snch through the test container (6) that drill fluid is circulated until it has left a filter cake and a micro annulus forming grease film on the container wall, separating fluid being circulated until the removal of filter cake and grease film is considered to be satisfactory. |
This invention relates to an apparatus and a method for the testing of concrete for use when cementing casings in oil and gas wells .
It is previously known equipment and methods for testing concrete/cement mixtures for the purpose concerned.
Thus, one known test apparatus is substantially intended to test the concrete/cement mixture with respect to micro silicium oxide content. With this known test method, a pipe having one closed end and a height of about 2 metres is filled with concrete to be tested and, above the concrete column, a water layer is placed, whereafter nitrogen gas is supplied from below. The test consists in observing the temperature development within the cement mixture og possible nitrogen gas penetration, the latter being observed through tiny gas bubbles in the water layer.
In another known test apparatus of this kind, the test parametres are the same as above, but in this case one uses a much longer pipe, about 10 metres, for the concrete/ cement mixture to be tested.
Systems based on these prior art technics suffer from a number of deficiencies and disadvantages substantially
associated with the one-sidedness of the systems and of which i.a. the following may be mentioned:
Known test apparatus can not be put under pressure in order to simulate the conditions normally existing in a subsea oil or gass well. The concrete/cement mixture to be tested can not be heated, neither in static condition nor during circulation and, therefore, the test can not be effected at the temperatures that are prevailing in the reservoir wherein the casing are to be securely casted by means of concrete, the nature of which is desired to test.
Likewise, it represents obvious disadvantages and deficiencies in conventional test eguipment that neither hydrostatic pressure (weight of concrete plus pressure above the concrete column) nor differential pressure can be measures. One may, indeed, observe possible flow of gas through the concrete column/sample, but prior art test equipment lack measuring instruments to measure the amount of gas penetrating into or flowing out from the concrete column. Further, the concrete/cement mixture can not be circulated and, consequently, one can not simulate a complete cementing operation in situ, which, additionally, presupposes circulation of mud and separating liguid.
Also, it is desirable to test concrete/cement mixture for cementing of casings within wells drilled in permafrost and, likewise, how concrete/cement mixzture behaves itself in deviated wells and horizontal wells. Moreover, it would involve obvious advantages to be capable of logging data (data of experience) for later use. Nothing of this is possible to realize by means of prior art concrete test methods and eguipment.
A main object of the present invention is, therefore, to provide a new apparatus and a new method of the kind defined
introductorily, wherein at least most of the described disadvantages, deficiencies and limitations of conventional technics have been completely eliminated or reduced to a substantial degree.
Thus, according to the invention, one has aimed at providing an apparatus and a method wherein concrete/cement mixture can be tested under conditions which in many respects simulate the conditions to which the concrete/cement mixture is anticipated to be subjected in connection with the casing cementing in subsea oil or gas wells, as well as deviated wells, highly deviated wells and horizontal wells.
The main object of the invention is realized through a combination of features appearing from the following independent claims. Subordinate, advantageous features are indicated in the dependent claims.
In principle, the invention consists in that the pipe containing the concrete sample is placed in a chamber, which may have the form of two hinged chamber halves, enabling the opening and closing of the chamber. The chamber is heatable (coolable) in order to simulate the heat (cold) within a subsea well, e.g. to 100 , and may be placed under pressure, e.g. a pressure anticipated to exist in the well concerned. When this pressure has been established, one may - according to the method of the invention - add an overpressure (differential pressure), in order to simulate a gas leak from the reservoir. After the test has been performed, the chamber is opened and the concrete sample taken out for closer analysis in a laboratory. The apparatus cfcccrding to the invention may be placed slopingly or horizontally, in order to simulate special conditions prevailing in deviated wells (horizontal wells).
In accordance with the invention, one may work with a
pressure within the test chamber of up to 1,000 psi, and one will be capable of testing cement mixtures from -5 C to +200°.
Hydrostatic pressure may be observed during the entire test period. Hydrostatic pressure corresponds to the weight of the cement mixture plus possible additional pressure and may be measured by means of a load cell as well as read off on a connected computer display. When the cement mixture hardens, it becomes self-supported and, then, the hydrostatic pressure descends to zero.
The added differential pressure may be adjusted from 0-15 psi with an accuracy of 0,02 psi. The magnitude of the differential pressure may be observed during the entire test.
The test equipment/method according to the invention enables to measure how much gas that possibly might have entered the cement mixture. This is important, because one then may calculate how far into the concrete column the gas has penetrated in those cases wherein the gas has not penetrated through the entire column. At the place where the gas possibly may be anticipated to penetrate, it is suitably placed a meter, in order to establish whether the penetration has been 100% or less. According to the method of the invention, one may add a certain number of millilitres gas in order to establish a differential pressure, the concrete later being taken out for analysis.
The importance of being capable " of circulating the cement mixture in accordance with the apparatus and the method of the present invention consists in that one thereby is able to simulate the course of time upon the pumping-in of the cement mixture into the bore hole. The importance of concrete testing under temperature and circulation
conditions prevailing within the bore hole is i.a. associated with the shear stress (shearing) to which the concrete is subjected during pumping and which may influence the time of hardening.
In its most advanced embodiment, the new apparatus is designed and adapted to enable the performance of an entire cementing operation under simulated conditions.
Prior to the pipe being filled with concrete, one may circulate therethrough preferably oil-based mud, the various chemicals (barite, bentonite) thereof depositing along the inner wall of the pipe. Such a depositing or scale is usually called the "filter cake". Moreover, when using an oil-based mud, a grease film will form innermost along the pipe wall. As a result of this fat layer, a micro annulus may be formed, which in practice is represented through a thin oil film between casing and concrete. This being done, one may pump in a separating liquid, in order to remove both the filter cake and the grease film. During this removal, one tests, of course, the properties of the separating liquid in relation to the mud used. It is of significant importance to remove the filter cake and the gease film so completely that the adhesion of the concrete to the casing becomes fully satisfactory. With unsatisfactory adhesion, the possibility exists that gas from e.g. a gas pocket gets the opportunity of escaping through said micro annulus between pipe wall and adjacent cement mixture surface. During the test, one uses the same liquids (mud and separating liquid) that are to be used during the initial steps of the real cementing operation.
It may be advantageous to store all information as data of experience, in order to, on the basis these possibly updated data, to improve de nature of the various cement mixtures. Examples of such important data is the period of hardening.
its temperature during the test, the amount of gas into and/or out of the sample, hydrostatic pressure and differential pressure.
These informations may be used in order to optimalize the various cement mixtures to be used for cementing casings within subsea oil and gas wells, over a very wide reservoir temperature area and under strongly differing pressure conditions. The data of experience may i.a. be used for the pure purpose of research, and in this connection it might be mentioned that gas migration in cement mixtures, especially at temperatures above 100 C, is poorly investigated.
When using a test apparatus, the construction thereof being explained later in connection with the special part of the description, the method according to the invention comprises substantially the following working operations in succession: (i) drilling fluid is circulated through the empty concrete-accommodating container pipe until a suitable filter cake has built itself up on the inner wall of the pipe, e.g. one hour; ( ii ) the circulation of drilling fluid is replaced with e.g. one time circulation of separating liquid which thereby displaces the filter cake; cement is circulated in order to simulate the course of the pumping with an actual operation, in that the cement mixture may be circulated for e.g. 1-6 hours; the nature of the mixture will then be approximately such it would have been in practice, said circulation causing the cement mixture to be subjected to shear stresses, as it will be when passing through pumps, pipes, bends and the like, such that the test apparatus and method create conditions simulating the journey of the cement mixture through the drill pipe string, wherein it is subjected to shear forces through its contact with the pipe string wall, against valves and the like; (iii) whereafter the level of the cement mixture within the container pipe is adjusted such that said level becomes
situated about 10 cm from the upper portion of the pipe, whereafter the concrete pumps are stopped; (iv) whereafter the test apparatus is set under pressure, e.g. 1000 psi, piping gas above and below the concrete column (which not necessarily has to be vertical but may form an arbitrary angle with a vertical axis, for testing concrete for cementing of casings in deviated wells/horizontal wells); (v) whereafter one establishes a differential pressure in sides of the chamber wall, whereby that extra pressure emanating from a reservoir during real operations is simulated; a filter may be arranged to distibute the gas around the concrete sample over 360 ; (vi) oil being circulated within the chamber in order to heat the jacket.
The heating oil heats the jacket for a desired time, i.e. until the cement mixture has hardened, e.g. 5-12 hours, whereafter the chamber is opened and the concrete sample taken out for analysis.
An example of an embodiment of a test apparatus according to the invention is further explained in the following, reference being made to the drawings, wherein:
Figure 1 shows an axial section through the test chamber with associated eguipment; apparatus for circulating cement mixture, drilling fluid and separating liquid have been deleted for the sake of clarity and because such apparatus probably not have to be illustrated separately, in that it in each case merely is a question of a simple circulation process within a closed circuit prior to supplying the cement mixture, etc., to the test apparatus;
Figure 2 shows, on the same scale as figure 1, a side elevational view, partly broken along the line II-II in figure 3;
Figure 3 shows a radial section along the line III-III in figure 1 on a scale approximately twice that of figures 1 and 2.
In accordance with the drawings, a test chamber incorporated in an apparatus for the testing of concrete for use when cementing casings within subsea oil and gas wells comprises two half cylindrical wall parts 1,1' interhinged by means of hinges 2 for opening and closing of the test chamber 1,1' . The chamber walls are formed as double walls, and within the spacings between the single jackets, an insulating material 3 is placed. Diametrally opposite the hinges 2, the outer chamber jackets 1,1' are provided with cooperating coupling means 4, the engagement of which may be releasably secured by means of a locking bolt or the like, not shown.
The inner single jackets of the chamber walls are, at each axial end, bended such that the double wall, which is concentrical elsewhere, attains a somewhat smaller thickness there. Such a design is suitable i.a. for the fitting of end covers on an inner pipe to be described later on. A number of longitudinal pipes 5 is fitted within the annular spacing between the inner chamber jacket and the adjacent wall of mounting portions of the hinges 2 and the coupling means 4.
The reference numeral 6 denotes the test pipe, i.e. the pipe wherein the cement mixture to be tested is filled and subjected to heat/cold influence, pressure influence, i.a. differential pressure influence, etc., and which beforehand may be influenced through circulated drilling fluid and separating liquid, in order to investigate whether these are compatible.
The insulation 3 serves to insulate the pipes 5 against loss of heat, said pipes 5 being formed for the accommodation of circulating heat or cold medium, e.g. hot oil, in order to
bring the test pipe up/down to the desired temperature, e.g. 1 10000°CC,, ccoorrnresponding to a rather normal reservoir temperature,
Oil or other hot heat/cold medium is pumped into and through the heating/cooling pipes 5 through a lower radially directed supply pipe 7 opening into a manifold 8 in the lower end portion of the test chamber 1,1' . The arrangement may e.g. be such that the heat/cold medium becomes pumped in through the pipe 7 and the lower manifold 8 and from there up through the pipes 5 in the left half 1 ' of the test chamber 1,1' , in order to, at the upper end of the latter, to be transferred to an upper manifold 9, from where the heat/cold medium through a flexible hose piece 10 enters into a further manifold 11 in communication with the top ends of the pipes 5 in the right half 1 of the chamber. Then, subsequent to flowing downwards through the last- mentioned group of pipes 5, the heat/cold medium passes a further bottom manifold 12 and from there through a pipe 13 to a pump, not shown.
A flexible hose piece 10 is used in order to enable the rotation of the chamber halves 1 and 1' in relation to each other by means of the hinges 2.
Thus, when the test chamber halves 1,1' occupy the swung- open position thereof, not shown, the test pipe 6 may be placed into the chamber.
The test pipe 6 is provided with screwed-on end caps 14, 14' . In the bottom end cap 14-, -a lo.ad cell 15 has been placed, the load cell 15 being adapted to display the hydrostatic pressure within the test pipe/chamber.
The bottom end cap 14 of the test pipe 6 has two axially through-going bores, each associated with a pipeline/hose
16,16' constituting two inlets to the test pipe. The upper end cap 14' of the test pipe 6 is formed correspondingly, and 17 and 17' denote two outlets of the test pipe.
Now, drill mud, separating liquid and cement mixture may be circulated through the test pipe 6 through the inlet 16 and the outlet 17.
Through the inlet 16', gas is conducted in order to put the pipe 6 under pressure, and gas that might have migrated through the concrete within the test pipe 6, may be read off on a meter, not shown, coupled to the outlet 17' .
Radially directed channels 18,18' extending through the double chamber wall, serve to supply gas in order to establish an overpressure (differential pressure). The reference numeral 19 denotes a filter, the task of which is to distribute this overpressure 360 around the concrete sample. Such a pressure distributing filter is not critical for the function of the invention but, nevertheless, it constitutes an advantageous feature contributing to improve the degree of accuracy of the test results.
The test apparatus according to the invention will be equipped with a temperature-indicating instrument for the temperature of the tested concrete; a measuring instrument for measuring and indication of the amount of gas into/out from the concrete sample; a pressure-indicating instrument for measuring and indication of the main pressure (i.e. pressure minus differential pressure) acting on the concrete sample, e.g. 1000 psi; a measuring instrument for the measuring of hydrostatic pressure, e.g. in the form of the load cell 15 shown; a pressure-indicating measuring instrument for the measuring and indication of differential pressure (established through gas supplied through the radial channels 18,18' ).