Apparatus and method for performing downhole measurements

Abstract: An apparatus for performing a function in a flowing fluid includes an apparatus body and a drag member associated with the apparatus body and configurable between drag configuration for moving with the fluid wherein the apparatus has a first drag and a reduced drag configuration for moving against the fluid wherein the apparatus has a second drag which is less than the first drag.

Description: The invention relates to an apparatus corresponding to the preamble of claim 1 and a method for performing a function in a flowing fluid and, more particularly, to a method and an apparatus for performing downhole measurements and the like. Oil and gas wells are drilled into oil and gas bearing formations so as to produce such oil and gas for use as fuel and numerous other products. In the course of such drilling and production, it is critical to obtain information as to the formations drilled through, as well as fluids within the well. Conventional methods for obtaining desirable information include core sampling from the well, measurement while drilling, logging while drilling and the like. These methods all provide critical information which is helpful in optimising drilling and production activities. Conventional equipment for obtaining this information includes electrical wiring and/or optical fiber in substantial lengths, for example equivalent to the depth of the well, and various other sensors and analytical equipment.. This equipment creates substantial cost and in some cases can require re-completion of a well for installation, particularly to install sensors in appropriate positions. Conventional equipment is frequently accompanied by poor robustness or reliability, which leads to poor performance over time. Sensors and other equipment are frequently not reusable and are expensive to install and/or replace. DE-A-2358371 discloses an apparatus in order to bring measuring instruments upwards to the daylight, which have been lowered into a bore hole by means of drill pipes. This is formed as an automotive floating body mounted to or connected with the measuring instrument. The volume weight of the floating body is variable. The common weight of the measuring instrument and of the floating body is lower than the specific gravity/volume weight of the well fluid circulating in the bore hole. The floating body has the form of a hollow body, and it has a valve, a device for liquid displacement, a gas generator and a time switch. The floating body has a storage for electric energy and is furthermore equipped with an electric motor controlled by a time switch and a driving device, which is a propeller or a driving wheel which is in glide contact with the side of the drill pipe. A self-propelling apparatus for well logging tools -- shown in US-A-3937278 -- includes a housing which is secured to the housing of a well logging tool and which defines a cylinder. A piston is slidably received in the cylinder, and a powder charge is mounted in the housing for electrical actuation. The cylinder is initially filled with a weighted fluid to establish a negative buoyancy whereby the well logging tool moves downwardly in a well to effect a logging operation. Upon completion of the well logging operation, a signal from the well logging tool actuates the powder charge whereby the piston forces the weighted fluid out of the cylinder and thereby establishes a positive buoyancy. This positive buoyancy together with the flow of the weighted fluid and the flow of gases resulting from the burning of the powder charge out of the housing combine to propel the well logging tool upwardly. At the top of the well the apparatus is siezed by latching apparatus and is retained thereby for subsequent retrieval. A method and apparatus is described in US-A-3789355 for monitoring at a remote location downhole conditions encountered while drilling a well. A sensed downhole condition is represented by a binary coded acoustic signal which is transmitted by way of a liquid path, provided by drilling liquid, to the surface of the earth. The acoustic signal, whose phase state represents bit values, is detected at the surface and decoded by way of a coherent system. Coherency is provided by deriving from the received signal a reference signal which is compared with the received signal to produce an output representative of the sensed condition. It is clear that the need remains for improved methods and equipment for obtaining downhole measurements. It is therefore the primary object of the present invention to provide an apparatus for obtaining downhole measurements which addresses the foregoing disadvantages of the prior art. It is a further object of the present invention to provide a method for obtaining downhole measurements. Other objects and advantages of the present invention will appear hereinbelow. The problems are solved by the teaching according to the independent claims. Particular developments are given in the dependent claims. Within the frame of the invention are all combinations of at least two of the descriptive elements and technical features disclosed in the claims and/or in the description. In accordance with the present invention, the foregoing objects and advantages have been readily attained. In accordance with the invention, an apparatus is provided for performing a function in a flowing fluid, which apparatus comprises an apparatus body and a drag member associated with said apparatus body and configurable between a drag configuration for moving with said fluid wherein said apparatus has a first drag, and a reduced drag configuration for moving against said fluid wherein said apparatus has a second drag which is less than said first drag. Said apparatus body comprises an elongated member having a longitudinal axis, and wherein said drag member comprises a substantially planar member having a planar surface which is positionable relative to said apparatus body between said drag configuration wherein said planar surface is substantially perpendicular to said axis and said reduced drag configuration wherein said planar surface is substantially parallel to said axis. The apparatus is advantageously provided with sensors for making desired measurements and can be controlled from a surface location. In further accordance with the present invention, a method is provided for positioning an apparatus relative to a flowing fluid, which method comprises the steps of providing a flow of fluid; providing an apparatus comprising an apparatus body and a drag member associated with said apparatus body and configurable between a drag configuration having a first drag for moving with said flow of fluid and a reduced drag configuration having a second drag for moving against said flow of fluid wherein said second drag is less than said first drag; positioning said apparatus in said flow of fluid with said drag member in said reduced drag configuration whereby said apparatus moves against said flow of fluid; and configuring said drag member in said drag configuration whereby said apparatus moves with said flow of fluid; selectively controlling the position of the apparatus in said flow of fluid and measuring with said apparatus at least one condition of said flowing fluid, at that selected position. Further advantages, characteristics and details of the invention are apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings, wherein: Fig. 1 schematically illustrates an oil well drilled to a producing formation and an apparatus positioned therein in accordance with the present invention; Fig. 2 illustrates an embodiment of the present invention in a reduced drag configuration for descending in a well; Fig. 3 illustrates an embodiment of the present invention in a drag configuration for moving upwardly in a well; and Fig. 4 illustrates a cycle path of use of the apparatus of the present invention for obtaining measurements along the depth of a well. The invention relates to an apparatus and method for performing a function in a flowing fluid, and particularly to an apparatus and method for obtaining downhole measurements in a subterranean well environment. In accordance with the present invention, an apparatus and a method for using the apparatus are provided which readily allow for obtaining various desirable measurements in a flowing fluid, for example in a producing oil and gas well, without the conventional disadvantages associated with utilizing equipment attached to wires such as conventional logs, and without the further disadvantages accompanied by installing permanent sensors in downhole locations. Fig. 1 schematically illustrates a typical oil producing well 10 which includes a production tubing 12 positioned from a surface location 14 to a subterranean formation 16 for producing fluid (schematically illustrated by arrows 18) from formation 16 to surface location 14 as desired. Fig. 1 also illustrates apparatus 20 in accordance with the invention which can advantageously be positioned within production tubing 12 and configured to travel from surface location 14 to deeper locations within production tubing 12, and back to surface location 14 when desired. Apparatus 20 can be utilized to obtain any and all desired measurements from various downhole locations along production tubing 12 as desired. It should of course be. appreciated that apparatus 20 is shown in Fig. 1 with exaggerated size so as to better illustrate the present invention. Turning to Fig. 2 and 3, apparatus 20 in accordance with the present invention is further illustrated. Apparatus 20 in accordance with the present invention preferably includes an apparatus body 22 for housing the various desired components of apparatus 20 as will be further discussed below. Apparatus body 22 is preferably a substantially elongate member having a longitudinal axis. The exterior surface of apparatus body 22 is preferably designed so as to provide a minimum amount of drag to fluids flowing past apparatus 20, or through which apparatus 20 is moving. For example, body 22 may be substantially cylindrical with tapered or rounded ends. Of course, other shapes are also suitable. Apparatus 20 also includes a drag member 24 which is configurable between a drag configuration (illustrated in Fig. 3) and a reduced drag configuration (illustrated in Fig. 2). This is further described below. In a producing well, fluids being produced typically include hydrocarbons, water and any other materials which might be encountered in the particular subterranean formation from which fluids are produced. These fluids flow upwardly through production tubing 12 to surface location 14 as desired. This flow may be driven by pressure within formation 16, and/or various other additional forces such as pumps, gas lift, and the like. In accordance with the present invention, apparatus 20 is adapted and configured such that, in the reduced drag configuration of Fig. 2, the force of gravity is sufficient to pull apparatus 20 downwardly through the upwardly flowing fluid so as to'move apparatus 20 against the flow of fluid and in a downward direction within production tubing 12 to deeper locations in the well. This advantageously allows apparatus 20 to be positioned at downhole locations as desired. When it is desired to return apparatus 20 to the surface, drag member 24 is configured to the drag configuration of Fig. 3, which has increased drag as compared to the reduced drag configuration, and which results in the drag force applied by upwardly flowing fluid overcoming the force of gravity and lifting apparatus 20 through production tubing 12 toward surface location 14 as desired. This advantageously allows for apparatus 20 to be positioned at any desired downhole location along production tubing 12, within flowing fluid 18, so as to obtain any desired measurements and the like without the need for conventional logging equipment and/or permanently installed sensors. Drag member 24 in accordance with the present invention may advantageously be provided as a plurality of substantially planar members 26 which can be positioned substantially parallel to the longitudinal axis of apparatus body 22 as shown in Fig. 2 so as to provide for a reduced drag configuration. In this configuration, the force of gravity G overcomes the drag of upwardly flowing fluid 18 resulting in downward motion D of apparatus 20 as desired. Planar members 26 can be configured or positioned, in this case through rotation, to a substantially horizontal position with respect to the longitudinal axis of apparatus body 22 as shown in Fig 3 so as to provide an increased drag configuration wherein the force of upwardly flowing fluid 18 overcomes the force of gravity G resulting in upward motion U as shown in Fig. 3. Positioning of drag member 24 between the drag configuration of Fig 3 and the reduced drag configuration of Fig. 2 may advantageously be accomplished from a remote location, for example using a preferably wireless control member or transmitter 28 (see Fig. 1) positioned at surface location 14 for issuing commands to apparatus 20. Commands can be received, for example through a receiver 30 on apparatus 20, for actuating a motor or motors (not shown) within apparatus body 22 for rotating planar members 26 between the desired positions. Fig. 2 and 3 illustrate planar members 26 positioned in a vertical position (Fig. 2) and in a horizontal position (Fig. 3) representing the minimum and maximum drag positions, respectively. It should be appreciated that planar member 26 could be partially pivoted between the positions of Fig. 2 and 3 so as to obtain an intermediate drag position which could be utilized, in combination with a sensor for detecting speed of movement within production tubing 12, to allow for obtaining an equilibrium position wherein apparatus 20 maintains substantially the same position within production tubing 12 for example if a particular measurement must be taken that requires being stationary at a particular level in the well for an extended length of time. By monitoring speed and position of apparatus 20, and adjusting drag member 24 appropriately, apparatus 20 can be positioned to any location within a well, and returned to the surface when desired. Further, the speed of descent and ascent can be controlled by changing the angle of the drag member to increase or decrease drag. As set forth above, it is a particular advantage of the present invention to be able to obtain various desirable downhole measurements without the need for conventional equipment such as fixed installation sensors and/or wired or otherwise connected devices. Thus, apparatus 20 is typically provided having one or more sensors or other analytical devices positioned on or within body 22 as schematically illustrated at 32 for example to obtain measurements of desired conditions. Such conditions may be fluid related conditions including pressure, temperature, density, viscosity, water content, composition, multiphase flow and the like. Additional information which may be desirable to obtain utilizing sensors 32 includes speed of movement of apparatus 20, position of apparatus 20 within production tubing 12, proximity of bottom 44 of well 10, and the like. The actual structure and/or circuitry of such sensors is well known to a person of ordinary skilled in the art and is therefore not described herein. Apparatus 20 in accordance with the present invention includes various electronic devices as described above. Such devices includes sensor 32 and one or more motors (not shown) for driving planar members 26 of drag member 24. A power source for these devices is preferably provided in the form of a rechargeable battery 34, which can ideally be positioned within apparatus body 22. Battery 34 may advantageously be rechargeable such that apparatus 20 can be recharged once it is retrieved at surface location 14. In accordance with a further preferred embodiment of the present invention, apparatus 20 may be provided having a fluid actuated charger or generator 36 operatively associated with rechargeable battery 34 and exposed to flowing fluid 18 within production tubing 12 so as to allow for potentially continuous recharging of battery member 34 if desired. The specific components and circuitry of battery 34 and charger 36 are also well known to a person of ordinary skill in the art and are therefore not included herein. For example, drag member 24 could be adapted to convert fluid momentum into rotation of drag member 24 as shown in Fig. 3. This rotation relative to the rest of apparatus 20 could be used to operate charger/generator 36. In this embodiment, stabilizing fins or other structure may be desired to prevent rotation of body 22 along with drag member 24. Of course, other configurations and structures could likewise be used to convert fluid momentum into stored energy for operating apparatus 20 as desired. Apparatus 20 may advantageously be provided with a control member programmed to provide for particular desirable functions. For example, apparatus 20 may include a control member programmed to sense when battery 34 has reached a low power state at which point drag member 24 could be automatically positioned to the drag position of Fig. 3 so as to allow for recovery of apparatus 20 at surface location 14 and recharging of battery 34 and the like. The control member may also advantageously be adapted to utilize particular information received by sensors 32 to enhance the downhole measurement ability of apparatus 20. For example, the control member of apparatus 20 may be adapted so as to detect the approach of the bottom 34 of production tubing 12 so that drag member 24 can be properly positioned to increase drag and slow descent of apparatus 20, thereby avoiding a potentially damaging collision with bottom 34 of production tubing 12. Still further, the control member of apparatus 20 may advantageously be adapted so as to detect abnormalities in one or more fluid conditions and automatically configure drag member 24 to remain at the particular location for an extended period of time obtain additional measurements. Apparatus 20 may also be provided with capacity for carrying one or more additives such as cement for local repairs, plugging material for selectively closing off one or more zones, or any other material which could advantageously be deployed within production tubing 12 by apparatus 20 if desired. In this embodiment, the control member for apparatus 20 would of course control deployment of such material as well. In accordance with the present invention, apparatus 20 is provided which is configurable to positions which increase and decrease the drag coefficient at the fluid-body interface between apparatus body 22 and flowing fluid 18. The total time-averaged force (F D ) exerted by the flow on an object can be written in a dimensionless manner, utilizing frontal area (A) of the object, as follows: C D = F D / A 1 2 ρ V 2 wherein C D is the drag coefficient and V is fluid velocity. In the embodiment of Fig. 2 and 3, drag member 24 operates by increasing and decreasing area A as well as changing local geometry which thereby adjusts the drag coefficient C D . Through this manipulation, apparatus 20 can be configured to move downwardly within production tubing 12 by the force of gravity, and can be configured to move upwardly with flow 18, utilizing energy provided by flow 18 on drag member 24. Apparatus 20 in accordance with the present invention will typically be exposed to conditions including temperatures between about 20°C and about 350°C and pressures between about 6, 895 bar (100 psi) and about 1723,75 bar (25000 psi). It is therefore preferable that apparatus body 22 be selected so as to withstand such conditions, and further that components within apparatus body 22 be selected so as to withstand such conditions. It should also readily be appreciated that communication between apparatus 20 and surface location 12 is accomplished utilizing wireless communications, thereby providing a marked improvement over conventional systems utilizing hardwiring and/or optical cables. Further, apparatus 20 in accordance with the present invention operates utilizing extremely low energy consumption, and can preferably be provided so as to recharge during use utilizing energy from the fluid. A typical cycle for use of apparatus 20 in accordance with the present invention will now be described. Use may typically be commenced by introducing apparatus 20 into well 10 utilizing a "lubricator" or any other port which is suitable for introducing apparatus 20 into production tubing 12 from surface location 14. Once apparatus 20 is within production tubing 12, communication is established between apparatus 20 and control member 28. A diagnostic may then advantageously be performed so as to insure all systems of apparatus 20 are functioning. Assuming that the diagnostic does not indicate any problems, drag member 24 may advantageously be configured to the reduced drag configuration of Fig. 2 and apparatus 20 will begin a smooth falling motion through upwardly flowing fluid 18 as desired. Fig. 4 illustrates schematically a cycle path with vertical position of apparatus 20 plotted over time, and various tasks being accomplished along the way. While apparatus 20 is travelling, various measurements are being taken including those which may be automatically programmed and those which may be requested by an operator at surface location 14. Apparatus 20 is preferably adapted to continuously monitor acceleration so as to maintain speed and acceleration below levels which could cause damage upon impact with production tubing 12 and other well equipment. Information obtained by apparatus 20 may be stored within apparatus 20, for example in local memory, and/or may be transmitted to control member 28 at surface location 14. During descent, should any abnormal situation be detected, apparatus 20 may be programmed and/or instructed to take an appropriate action. For example, as illustrated at point 38 in Fig. 4, it may be desirable to slow or stop descent of apparatus 20 in production tubing 12 so as to perform a further specific measurement task and the like. Upon completion, drag member 24 can again be configured to the reduced drag configuration so as to continue descent as illustrated. Upon reaching a further downhole point, for example point 40 as illustrated in Fig. 4, an additional task may be performed. Further, if it is now detected that apparatus 20 has reached a close proximity to the bottom of the well, apparatus 20 may advantageously be configured to the drag position of Fig. 3 for ascent through production tubing 12 back to surface location 14 as desired. It should be readily appreciated that apparatus 20 and the use of same provide for substantial advantages as compared to conventional systems and methods for obtaining downhole measurements. Specifically, apparatus 20 avoids the need for permanent installations downhole, and also avoids the need for wired connections or optical connections extended over substantial lengths such as the entire depth of a well and the like.

Claims: An apparatus (20) for performing a function in a flowing fluid (18), comprising an apparatus body (22) and a drag member (24) associated with said apparatus body (22) and configurable between a drag configuration for moving with said fluid (18) wherein said apparatus (20) has a first drag and a reduced drag configuration for moving against said fluid (18) wherein said apparatus (20) has a second drag which is less than said first drag, wherein said apparatus body (22) comprises an elongated member having a longitudinal axis, and wherein said drag member (24) comprises a substantially planar member (26) having a planar surface, characterised in that said planar surface is positionable relative to said apparatus body (22) between said drag configuration wherein said planar surface is substantially perpendicular to said axis and said reduced drag configuration wherein said planar surface is substantially parallel to said axis. The apparatus according to claim 1, further comprising a control member (28) remotely associated with said drag member (24) for configuring said drag member (24) between said drag configuration and said reduced drag configuration. The apparatus according to claim 1 or 2, further comprising a rechargeable power source (34) within said apparatus body (22) and a fluid actuated charger (36) positioned on said apparatus body (22) for charging said power source when said apparatus (20) is exposed to said flowing fluid (18). The apparatus according to one of the claims 1 to 3, further comprising a sensor member (32) mounted relative to said apparatus body (22) for sensing at least one condition of said flowing fluid (18) selected from the group consisting of pressure, temperature, density, viscosity, water content, composition and multiphase flow. The apparatus according to claim 4, further comprising a transmitter member (28) mounted to said apparatus body (22) and a receiver (30) positioned remotely relative to said apparatus body (22), said transmitter (28) being adapted to said transmitting said at least one condition to said receiver (30). The apparatus according to claim 4, further comprising a storage member mounted to said apparatus body (22) for storing said at least on condition. The apparatus according to one of the claims 1 to 6, further comprising a position sensor member (32) mounted to said apparatus body (22) for sensing position of said apparatus (20). The apparatus according to one of the claims 1 to 7, wherein said drag member (24) is configurable to at least one partial drag configuration between said drag configuration and said reduced drag configuration whereby drag relative to said fluid can be adjusted. A method for positioning an apparatus (20) relative to a flowing fluid (18), comprising the steps of: providing a flow of fluid (18); providing an apparatus (20) comprising an apparatus body and a drag member (24) associated with said apparatus body (22) and configurable between a drag configuration having a first drag for moving with said flow of fluid (18) and a reduced drag configuration having a second drag for moving against said flow of fluid (18) wherein said second drag is less than said first drag; positioning said apparatus (20) in said flow of fluid (18) with said drag member (24) in said reduced drag configuration whereby said apparatus (20) moves against said flow of fluid (18) and configuring said drag member (24) in said drag configuration whereby said apparatus (20) moves with said flow of fluid (18); selectively controlling the position of the apparatus (20) in said flow of fluid (18) and measuring with said apparatus (20) at least one condition of said flowing fluid (18) at that selected position. The method according to claim 9, wherein said flow of fluid (18) is a substantially vertical flow of fluid (18). The method according to claim 9, wherein said flow of fluid (18) is in a directional substantially opposite to gravitational forces on said apparatus (20). The method according to claim 9, wherein said flow of fluid is in a well (10) producing fluid from a subterranean formation to a surface location (14). The method according to claim 12, further comprising controlling configuration of said drag member (24) from said surface location (14) when said apparatus (20) is in said well (10). The method according to claim 12 or 13, further comprising the step of measuring, with said apparatus (20), at least one condition of said flowing fluid (18) selected from the group consisting of pressure, temperature, density, viscosity, water content, composition and multiphase flow. The method according to claim 12, 13 or 14, further comprising the step of transmitting said at least one condition from said apparatus (20) in said well (10) to said surface location (14). The method according to one of the claims 9 to 15, further comprising the step of measuring, with said apparatus (20), at least one condition of said flowing fluid selected from the group consisting of pressure, temperature, density, viscosity, water content, composition and multiphase flow. The method according to one of the claims 9 to 16, further comprising the step of storing said at least one condition in said apparatus (20). The method according to one of the claims 9 to 17, further comprising the step of detecting with said apparatus (20) a position of said apparatus (20) relative to said flow of fluid (18).

Inventors: ARAUJO MARIELA, ESPIN DOUGLAS, RANSON AARON, ZAPICO JOSE, ARAUJO, MARIELA, ESPIN, DOUGLAS, RANSON, AARON, ZAPICO, JOSE
Applicants: INTEVEP SA
Application year: 2001
Main classification: E21B47
IPC codes: E21B23, E21B41, E21B27, E21B47