Apparatus and method for evaluating a formation

Abstract

An apparatus and method for evaluating a formation is presented. The apparatus comprises a tubular string deployed into a wellbore penetrating the formation, where the tubular string has a longitudinal flow passage therethrough. A flow sub in the tubular string provides fluid communication between the longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore. A wireline tool is attached proximate a bottom end of the flow sub. A telemetry module proximate the flow sub provides communication between the wireline tool and a surface system, without the use of a wireline to the surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to logging of subsurface reservoirs and more particularly to pipe conveyed logging.

2. Description of the Related Art

Ordinarily, gravity is used to pull logging tools along and into a well borehole for conducting logging operations. When a well is highly deviated from vertical, the force exerted by gravity may not be sufficient to draw the logging tool through a deviated portion of the well. Many oil wells are deviated. For example, an offshore platform commonly has many wells drilled from the platform into various portions of a targeted formation that surrounds the location of the platform. While some of the wells might be approximately vertical, most of the wells extending from the platform will deviate at various angles into the formations of interest and some may involve deviations up to, or above, horizontal. Gravity conveyed logging tools supported on wirelines lose the effect of gravity for forcing the tool through the hole and simply do not have sufficient motive force to traverse the deviated hole to the zone to be logged. In many instances, the logging tool must be pushed through the deviated well to the zone of interest to ensure that the logging tool is located at the requisite location in the deviated hole. It is desirable therefore that the logging tool be fixed to the end of a string of sufficiently stiff pipe to log along the deviated well at the zone of interest. In many cases, this requires using large pipe, such as drill pipe, to have the stiffness required for logging these sections.

A known method for logging highly deviated wells, disclosed in U.S. Pat. No. 4,457,370, to Wittrisch, consists of the following steps. A well logging tool is secured to the bottom of a section of drill pipe, inside a protective sleeve, and the tool is lowered into the well as additional sections of pipe are assembled. An electrical connector attached to the end of a wireline cable is then inserted into the drill pipe, the cable is passed through a side entry sub mounted on top of the drill string and the connector is pumped down through the drill pipe into engagement with a mating connector attached to the logging tool to effect connection of the tool to the cable and therefore the surface control equipment. Then other sections of drill pipe are added, the portion of the cable above the side entry sub running outside the drill pipe, until the tool reaches the bottom of the section to be logged. Then the logging operation is performed as the drill pipe is moved through the desired section.

The running of the cable and the additional care and complexity required to protect the cable during pipe movement increase the time required to obtain a log. In addition the making of a wet connect is commonly prone to failure requiring additional time and effort to correct.

There is a demonstrated need for providing an apparatus and method for logging a highly deviated wellbore that does not require the running of a wireline cable or the making of a wet connect.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an apparatus for evaluating a formation comprises a tubular string deployed into a wellbore penetrating the formation, where the tubular string has a longitudinal flow passage therethrough. A flow sub in the tubular string provides fluid communication between the longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore. A wireline tool is attached proximate a bottom end of the flow sub. A telemetry module proximate the flow sub provides communication between the wireline tool and a surface system, without the use of a wireline to the surface.

In another aspect, a method for evaluating a formation comprises deploying a tubular string into a wellbore penetrating the formation. Fluid communication is provided between a longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore using a flow sub attached to the tubular string. A parameter of interest is measured with a wireline tool attached to the tubular string below the flow sub. Communication between the wireline tool and a surface system is accomplished without the use of a wireline.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present invention, references should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:

FIG. 1 is a drawing of a logging system according to at least one embodiment of the present invention;

FIG. 2 is a blown up portion of bottom assembly 30 of FIG. 1;

FIG. 3 is a drawing showing an example of multiple sample tanks in a formation test tool; and

FIG. 4 is a block diagram of the interrelationship of several components of the present invention.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 and 2 show an exemplary embodiment of the present invention. Rig 5 supports a string 13 of jointed pipe in borehole 15, also called a wellbore, that extends through formation 20. As shown, borehole 15 is highly deviated and may include substantially horizontal sections. As used herein, highly deviated refers to wellbores that are deviated from vertical by about 70 degrees, or more. String 13 is made up of pipe sections 10 joined together at threaded connections 12. The pipe may be drill pipe of the type known in the art. String 13 extends in borehole 13 into a subterranean formation 20. Bottom assembly 30 is attached to the bottom of string 15 and comprises telemetry module 35, and flow sub 31. Attached below flow sub 31 are wireline logging tools 32A and 32B. As one skilled in the art will appreciate, and as used herein, a wireline tool is intended to be a tool designed to be commonly deployed into and out of the wellbore on an electrical wireline cable, and is distinguished from tools designed for use during measurement while drilling (MWD) operations. Commonly, wireline tools are not designed to survive the shock, vibration, and torsion of the drilling operation, as required by MWD tools. It is understood, in the context of the present invention, that minor mechanical modifications to a wireline tool to mechanically interface the tool for the present invention, do not alter the nature of the tool as a wireline tool.

As shown, tool 32A is a formation test tool. Logging tool 32B comprises a logging tool that may include, but is not limited to, at least one of: a nuclear magnetic resonance logging tool (NMR); a resistivity tool; and a nuclear density tool. Such tools are used to determine various parameters of interest of the formation including, but not limited to: formation resistivity, formation porosity, and formation permeability. Multiple wireline logging tools may be connected together in a logging string below flow sub 31. It should be noted that there is no significance to the specific location of particular logging tools in the logging string. For example, if multiple wireline tools are connected below flow sub 31, formation test tool 32A may be located at any location in the logging string.

Surface pump 3 pumps fluid 38 through string 13 and down through bottom assembly 30. Fluid 38 exits through flow port 50 in flow sub 31 into the annulus between the string 13 and the wall 14 of borehole 15 where it returns to the surface. While only one flow port 50 is shown, additional ports are located around the circumference of flow sub 31. Energy conductor 51 is disposed within the body of flow sub 31 and enables power and information to be communicated between wireline logging tools 32A and 32B and pulser 53, described below. Alternatively, multiple conductors may be routed in similar fashion.

Fluid 38 provides flow energy to power turbine/alternator 52 (shown in cutaway inside telemetry module 35, and in FIG. 2) to generate sufficient electrical power to operate the downhole logging tools and other downhole devices described herein. Such turbine/alternators are known in the art and are not discussed, in detail, here.

Telemetry module 35 also contains oscillating shear valve pulser 53, see FIG. 2, wherein rotor 60 oscillates proximate stator 61 to restrict a portion of flow of fluid 38 thereby generating pressure signals 41 that propagate to the surface through fluid 38. Pressure signals 38 are detected by transducer 7 that is in fluid communication with the output flow line of pump 3. Transducer 7 is commonly a pressure transducer of a kind known in the art. Alternatively, transducer 7 may be a flow transducer in line with the pump output detecting changes in flow related to pressure signals 41. For additional details of the operation of oscillating shear valve pulser 53, see U.S. Pat. No. 6,626,252, assigned to the assignee of this application and which is incorporated herein by reference. While described herein as used with a shear valve pulser, any suitable downhole mud pulser is intended to be within the scope of the present invention. Such pulsers include, but are not limited to: positive pulsers, negative pulsers, and continuous, also called siren, pulsers. In addition, surface located downlink pulser 4 transmits pulses 42 from the surface controller 8 to the downhole system. Pulses 42 contain instructions and status information used for operating the downhole system.

Alternatively, other types of transmission schemes known in the art, that do not employ a wireline connection between the surface and the wireline tool, are intended to be within the scope of the present invention. These include, but are not limited to: acoustic transmission through the pipe wall and electromagnetic telemetry.

In one embodiment, wireline tool 32A is a formation test tool such as those described in U.S. Pat. Nos. 5,303,775; 5,377,755; 5,549,159; 5,587,525; 6,420,869; 6,683,681; 6,798,518; and published application US 2004/0035199 A1, each of which is assigned to the assignee of this application, and each of which is incorporated herein by reference. Anchors 36 and sample probe 34 are extendable from the body of tool 32A to force sample probe 34 into contact with wellbore wall 14 and hence into fluid communication with formation 20. In one embodiment, as illustrated in FIG. 3, the tool 32A of FIG. 1 is shown to incorporate a bi-directional piston pump mechanism shown generally at 124 which is illustrated schematically. Within the tool 32A is also provided at least one and preferably a plurality of sample tanks such as exemplary tanks 126 and 128, which may be of identical construction if desired. The piston pump mechanism 124 defines a pair of opposed pumping chambers 162 and 164 which are disposed in fluid communication with the respective sample tanks via supply conduits 134 and 136. Discharge from the respective pump chambers to the supply conduit of a selected sample tank 126 or 128 is controlled by electrically energized three-way valves 127 and 129 or by any other suitable control valve arrangement enabling selective filling of the sample tanks. The respective pumping chambers are also shown to have the capability of fluid communication with the subsurface formation of interest via pump chamber supply passages 138 and 140 which are defined by the sample probe 34 of FIG. 1 and which are controlled by appropriate valving. The supply passages 138 and 140 may be provided with check valves 139 and 141 to permit overpressure of the fluid being pumped from the chambers 162 and 164 if desired. While described with two sample tanks, additional sample tanks may be added as desired. Additional details of the operation and design of tool 32A are contained in the incorporated references. Parameters of interest of the sampled fluid and the formation may be determined with sensors such as, for example, optical sensors, density sensors, pressure sensors, and temperature sensors incorporated in tool 32A. The parameters include, but are not limited to, formation pressure, sample fluid refractive index, sample fluid bubble-point, sample fluid density, sample fluid resistivity, and sample fluid composition.

In one embodiment, see block diagram in FIG. 4, wireline tools 32A-D are substantially unmodified for use in the present invention. As such, the power, commands, and data transmission to and from wireline tools 32A-D are substantially the same as if the tools were connected by a conventional wireline to the surface. This capability allows use of a variety of off-the-shelf logging tools in the present invention. Downhole controller 405 contains suitable circuitry in interface module 406 to emulate the appropriate functions necessary to operate and control wireline tools 32A-D. Controller 405 also comprises a processor 407 and memory 408. At least a portion of memory 408 contains programmed instructions for use by interface module 406 in the control of the operation of wireline tools 32A-D. Additional circuitry (not separately shown) is adapted to receive power form turbine-alternator 52 and appropriately distribute the power to the downhole components. Additional circuitry and instructions stored in downhole controller 405 are used to process the measurement data received form wireline tools 32A-D and to format this information for transmission by the mud pulse system to the surface. In addition, because the volume of data collected by the wireline tools 32A-D is commonly orders of magnitude greater than the capacity of the telemetry channel 401, when using mud pulse, the measurement data or suitable subsets thereof may be stored in memory 408 for later retrieval when the tools are returned to the surface. Programmed instructions resident in controller 405 are used to determine the appropriate transmission and storage protocols.

In one embodiment, surface system 400 contains surface controller 8 that sends commands via downlink pulser 4 to command initiation of various downhole functions, such as, for example performing a formation test. The commands, encoded as pulses 42 are received by a suitable sensor in telemetry module 35, such as for example, a pressure sensor (not separately shown). Once the commands are received and interpreted, downhole controller 405 assumes substantially autonomous control of the formation test. This may include data acquisition and interpretation to determine that a suitable result is obtained. Instructions and decision rules programmed into controller 405 are used to control this operation. Other downlink commands may, for example, cause changes in the encoding and pulsing format to enhance detection at the surface.

While described herein as a system used in a highly deviated wellbore, it is intended that the invention described herein is also to be used for deploying heavy wireline tools, or heavy strings of tools, that may be too heavy to be safely conveyed into and out of wellbores that are not highly deviated, including vertical wellbores.

The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible. It is intended that the following claims be interpreted to embrace all such modifications and changes.

Claims

1. An apparatus for evaluating a formation, comprising:

a tubular string deployed into a wellbore penetrating the formation, the tubular string having a longitudinal flow passage therethrough;

a flow sub in the tubular string, said flow sub providing fluid communication between the longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore;

a wireline tool attached proximate a bottom end of the flow sub; and

a telemetry module proximate the flow sub providing communication between the wireline tool and a surface system, without the use of a wireline to the surface.

2. The apparatus of claim 1, further comprising a downhole power source.

3. The apparatus of claim 2, wherein the downhole power source comprises a turbine-alternator disposed in a fluid flowing in the axial flow passage and generating electrical power therefrom.

4. The apparatus of claim 1, wherein the tubular string comprises drill pipe.

5. The apparatus of claim 1, wherein the wireline tool comprises at least one of: a formation test tool; a resistivity tool, a nuclear tool, and a nuclear magnetic resonance tool.

6. The apparatus of claim 1, wherein the telemetry module comprises a mud pulser transmitting encoded pulses in the flowing fluid that are detected by the surface system.

7. The apparatus of claim 1, wherein the surface system comprises a surface pulser transmitting a downlink signal to the telemetry module.

8. The apparatus of claim 7, wherein the downlink signal comprises commands for operation of at least one of the wireline tool and the telemetry module.

9. The apparatus of claim 1, wherein the telemetry module comprises a controller having a processor and a memory.

10. The apparatus of claim 9, wherein a signal from the wireline tool is stored in the memory in the telemetry module.

11. The apparatus of claim 1, wherein the wellbore comprises a highly deviated wellbore.

12. A method for evaluating a formation, comprising:

deploying a tubular string into a wellbore penetrating the formation;

providing fluid communication between a longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore using a flow sub attached to the tubular string;

measuring a parameter of interest with a wireline tool attached to the tubular string below the flow sub; and

communicating between the wireline tool and a surface system without the use of a wireline.

13. The method of claim 12, further comprising supplying electrical power proximate the flow sub.

14. The method of claim 12, wherein the tubular string comprises drill pipe.

15. The method of claim 12, wherein the wireline tool is chosen from the group consisting of: a formation test tool; a resistivity tool, a nuclear tool, and a nuclear magnetic resonance tool.

16. The method of claim 12, wherein the step of communicating between the wireline tool and a surface system without the use of a wireline comprises generating encoded mud pulses in a fluid and detecting the encoded pulses at the surface.

17. The method of claim 12, wherein the step of communicating between the wireline tool and a surface system without the use of a wireline comprises transmitting a downlink signal from the surface system to a telemetry module proximate the wireline tool.

18. The method of claim 17, wherein the downlink signal comprises commands for operation of at least one of the wireline tool and the telemetry module.

19. The method of claim 17, wherein the telemetry module comprises a controller having a processor and a memory.

20. The method of claim 12, wherein a signal from the wireline tool is stored in the memory in the telemetry module.

21. The method of claim 13, wherein the step of supplying electrical power proximate the flow sub comprises inserting a turbine-alternator disposed in a flowing fluid downhole and generating electrical power therefrom.