Abstract:
A borehole conveyance system that integrates wireline type downhole instrumentation into the drill string tripping operations that are typically performed in a borehole drilling operation to increase the types of measurements that can be obtained during the drilling operation and reduce equipment costs and maintenance costs. Certain wireline type tools can be used during drilling operations to yield measurements superior to their LWD/MWD counterparts, but not during any drilling operation in which the drill string is rotating while other types of wireline tools can be used to obtain measurements not possible with LWD/MWD systems.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. provisional application No. 60/614,320 filed Sep. 29, 2004. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention is directed toward apparatus and methods for conveying and operating analytical instrumentation within a well borehole. More specifically, the invention is directed toward measurements of borehole conditions and parameters of earth formation penetrated by the borehole using a tubular to convey the required analytical instrumentation. 
   2. Background of the Art 
   Properties of borehole environs are of great importance in hydrocarbon production. These properties include parameters related to the borehole, parameters related to properties of formations penetrated by the borehole, and parameters associated with the drilling and the subsequent production from the borehole. Borehole parameters include temperature and pressure, borehole wall imaging, caliper, orientation and the like. Formation properties include density, porosity, acoustic velocity, resistivity, formation fluid type, formation imaging, pressure and permeability. Parameters associated with drilling include weight on bit, borehole inclination, borehole direction and the like. 
   Properties of borehole environs are typically obtained using two broad types or classes of geophysical technology. The first class is typically referred to as wireline technology, and the second class is typically referred to as “measurement-while-drilling” (MWD) or “logging-while-drilling” (LWD). 
   Using wireline technology, a downhole instrument comprising one or more sensors is conveyed along the borehole by means of a cable or “wireline” after the well has been drilled. The downhole instrument typically communicates with surface instrumentation via the wireline. Borehole and formation measurements are typically obtained in real time at the surface of the earth. These measurements are typically recorded as a function of depth within the borehole thereby forming a “log” of the measurements. Basic wireline technology has been expanded to other embodiments. As an example, the downhole instrument can be conveyed by a tubular such as coiled production tubing. As another example, downhole instrument is conveyed by a “slick line” which does not serve as a data and power conduit to the surface. As yet another example, the downhole instrument is conveyed by the circulating mud within the borehole. In embodiments in which the conveyance means does not also serve as a data conduit with the surface, measurements and corresponding depths are recorded within the tool, and subsequently retrieved at the surface to generate the desired log. These are commonly referred to as “memory” tools. All of the above embodiments of wireline technology share a common limitation in that they are used after the borehole has been drilled. 
   Using MWD or LWD technology, measurements of interest are typically made while the borehole is being drilled, or at least made during the drilling operation when the drill string is periodically removed or “tripped” to replace worn drill bits, wipe the borehole, set intermediate strings of casing, and the like. 
   Both wireline and LWD/MWD technologies offer advantages and disadvantages which generally known in the art, and will mentioned only in the most general terms in this disclosure for purposed of brevity. Certain wireline measurements produce more accurate and precise measurements than their LWD/MWD counterparts. As an example, dipole shear acoustic logs are more suitable for wireline operation than for the acoustically “noisy” drilling operation. Certain LWD/MWD measurements yield more accurate and precise measurements than their wireline counterparts since they are made while the borehole is being drilled and before drilling fluid invades the penetrated formation in the immediate vicinity of the well borehole. As examples, certain types of shallow reading nuclear logs are often more suitable for LWD/MWD operation than for wireline operation. Certain wireline measurements employ articulating pads which directly contact the formation and which are deployed by arms extending from the main body of the wireline tool. Examples include certain types of borehole imaging and formation testing tools. Pad type measurements are not conceptually possible using LWD/MWD systems, since LWD/MWD measurements are typically made while the measuring instrument is being rotating by the drill string. Stated another way, the pads and extension arms would be quickly sheared off by the rotating action of the drill string. 
   SUMMARY OF THE INVENTION 
   The present invention is a borehole conveyance system that integrates wireline type downhole instrumentation into the drill string tripping operations that are typically performed in a borehole drilling operation. This increases the types of measurements that can be obtained during the drilling operation. Equipment costs and maintenance costs are often reduced. Certain wireline type tools can be used during drilling operations to yield measurements superior to their LWD/MWD counterparts, but not during any drilling operation in which the drill string is rotating. Other types of wireline tools can be used to obtain measurements not possible with LWD/MWD systems. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the manner in which the above recited features, advantages and objects of the present invention are obtained and can be understood in detail, more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. 
       FIG. 1  illustrates a borehole conveyance system for a wireline tool, with the conveyance system deployed using a drill string in a borehole environment; 
       FIG. 2   a  shows the borehole conveyance system with the wireline tool contained within; 
       FIG. 2   b  shows the borehole conveyance system with the wireline tool attached thereto and deployed in the borehole; 
       FIG. 3  shows a hybrid system with the wireline conveyance system combined with a LWD/MWD instrument, wherein the wireline tool is deployed in the borehole; 
       FIG. 4   a  shows a LWD/MWD subassembly combined with a telemetry and power subsection of the borehole conveyance system to form a LWD/MWD system for measuring parameters of interest while advancing the borehole; and 
       FIG. 4   b  shows a LWD/MWD subassembly combined with the wireline conveyance system such that the wireline tool and LWD/MWD sensors share a common power source and a common downhole telemetry unit. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  illustrates a borehole conveyance system  100  that is used to integrate wireline type downhole instrumentation into the tripping operations used periodically during a well borehole drilling operation. A wireline tool conveyance subsection  10  (wireline conveyance sub “WCS”) is operationally attached to a telemetry-power subsection  12  (“telemetry-power sub “TPS”) and suspended within a borehole  14  by means of a drill string  18  through a connector head  13 . The borehole  14  penetrates earth formation  32 . The lower end of WCS  10  is optionally connected to a wiper  17 . The upper end of the drill string  18  is terminated at a rotary drilling rig  20 , which is known in the art and illustrated conceptually. Drilling fluid or drilling “mud” is pumped down through the drill string  18  and through conduits in the TPS  12  and WCS  10 , wherein the conduits are illustrated conceptually with the broken lines  11 . Drilling mud exits the lower end of the WCS  10  and returns to the surface of the earth via the borehole  14 . The flow of the drilling mud is illustrated conceptually by the arrows  15 . 
   Still referring to  FIG. 1 , elements in the TPS  12  communicate with an uphole telemetry unit  24 , as illustrated conceptually with the line  22 . This link can include, but is not limited to, a mud-pulse telemetry system, an acoustic telemetry system or an electromagnetic telemetry system. Downhole measurements are received by the uphole telemetry unit  24  and processed as required in a processor  26  to obtain a measure of a parameter of interest. The parameter of interest is recorded by a suitable electronic or “hard-copy” recording device  28 , and preferably displayed as a function of depth at which it was measured as a log  30 . 
     FIG. 2   a  is a more detailed view of the WCS  10  and the TPS  12 . A wireline tool  40  is shown deployed within the mud flow conduit illustrated by the broken lines  11 . In the context of this disclosure, the term “wireline” tool includes tools operated with a wireline, tools operated with a slick line, and memory tools conveyed by drilling fluid or gravity. 
   Wireline logging systems have been used for decades, with the first system being operated in a borehole in the late 1920&#39;s. The tools typically vary in outside diameter from about 1.5 inches to over 4 inches. Lengths can vary from a few feet to 100 feet. Tool housings are typically fabricated to withstand pressures of over 10,000 pounds per square inch. Power is typically supplied from the surface of the earth via the wireline cable. Formation and borehole data, obtained by sensors in the downhole tool, can be telemetered to the surface for processing. Alternately, sensor data can be processed within the wireline tool, and “answers” telemetered to the surface. The patent literature abounds with wireline tool disclosures. U.S. Pat. Nos. 3,780,302, 4,424,444 and 4,002,904 disclose the basic apparatus and methods of a wireline logging system, and are entered herein by reference. 
   Again referring to  FIG. 2   a,  the upper end of the wireline tool  40  is physically and electronically connected to an upper connector  42 . The TPS  12  comprises a power supply  48  and a downhole telemetry unit  46 . The power supply  48  supplies power to the wireline tool  40  through the connector  42 , when configured as shown in  FIG. 2   a.  The power supply  48  also provides power to the downhole telemetry unit  46 , as illustrated by the functional arrow. The downhole telemetry unit  46  is operationally connected, through the upper connector  42 , to the wireline tool  40  via the communication link represented conceptually by the line  52 . The communication link  52  can be, but is not limited to, a hard-wire or alternately a “short-hop” electromagnetic communication link. As shown in  FIG. 2   a,  a wireline tool can be conveyed into a well borehole  14  (see  FIG. 1 ) using a tubular conveyance means such as a drill string  18 . The WCS  10  tends to shield the wireline tool  40  from many of the harsh conditions encountered within the borehole  14 . Furthermore, the tool  40  is in communication with the surface using the downhole and uphole telemetry units  46  and  24 , respectively, over the communication link  22  which can be, but is not limited to, a mud pulse telemetry system, an acoustic telemetry system, or an electromagnetic telemetry system. 
   The outside diameter of the wireline tool  40  is preferably about 2.25 inches (5.72 centimeters) or less to fit within the conduit  11  of the WCS  10  and allow sufficient annular space for drilling fluid flow. 
   Once the desired depth is reached, the wireline tool  40  is deployed from the WCS  10 . A signal is sent preferably from the surface via the telemetry link  22  physically releasing the tool  40  from the upper connector  42 . Drilling fluid flow within the conduit  11  and represented by the arrow  15  pushes the tool  40  from the WCS  10  and into the borehole  14 , as illustrated in  FIG. 2   b.  If the tool  40  is a pad type tool, arms  60  are opened from the tool body deploying typically articulating pads against or near the formation  32 . The deployed tool is physically and electrically connected to a lower connector  44 , such as a wet connector. Electrical power is preferably supplied from the power supply  48  to the tool  40  by means of a wire  50  within the wall of the WCS  10 . Alternately, power can be supplied by a coiled wire (not shown) extended inside the flow conduit (illustrated by the broken lines  11 ) from the upper connector  42  to the lower connector  44 . Telemetric communication between the deployed tool  40  and the downhole telemetry unit  46  is preferably through the lower connector  44 , and is illustrated conceptually with the line  54 . Again, the communication link can include, but is not limited to, a hard wire or an electromagnetic short-hop system. Communication between the downhole telemetry unit  46  and the uphole telemetry unit  24  is again via the previously discussed link  22 . Again, it should be understood that the wireline tool  40  can be a non-pad device. 
   Well logging methodology comprises initially positioning the conveyance system  100  into the borehole  12  at a predetermined depth, and preferably in conjunction with some other type if interim drilling operation such as a wiper trip. This initial positioning occurs with the wireline tool  40  contained within the WCS  10 , as shown in  FIG. 2   a.  At the predetermined depth and preferably on command from the surface, the wireline tool is released from the upper connector  42 , forced out of the WCS  10  by the flowing drilling fluid (arrow  15 ), and retained by the lower connector  44 . This tool-deployed configuration is shown in  FIG. 2   b.  The system  100  is preferably conveyed upward within the borehole by the drill string  18 , and one or more parameters of interest are measured as a function of depth thereby forming the desired. log or logs  30  (see  FIG. 1 ). If the wireline tool  40  is a formation testing tool, the system is stopped at a sample depth of interest, and a pressure sample or a fluid sample or both pressure and fluid samples are taken from the formation at that discrete depth. Alternately, formation pressure can be made, of formation pressure measurements and formation fluid sampled can both be acquired. The conveyance system  100  is subsequently moved and stopped at the next sample depth of interest, and the formation fluid sampling procedure is repeated. 
   The conveyance system  100  can be combined with an LWD/MWD system to enhance the performance of both technologies. As discussed previously, it is advantageous to use LWD/MWD technology to determine certain parameters of interest, and advantageous and sometimes necessary to use wireline technology to determine other parameters of interest. Certain types of LWD/MWD measurements are made most accurately during the drilling phase of the drilling operation. Other LWD/MWD measurements can be made with equal effectiveness during subsequent trips such as a wiper trip. As discussed previously, wireline conveyed logging can not be performed while drilling, and the conveyance system  100  can not be included in the drill string during actual drilling. Drilling LWD/MWD measurements and wireline conveyed measurements must, therefore, be made in separate runs. In order to accurately combine measurements made during two separate runs, the depths of each run must be accurately correlated over the entire logged interval. 
   A hybrid tool comprising the wireline conveyance system  100  and a LWD/MWD subsection or “sub”  70  is shown in  FIG. 3 . As shown, the LWD/MWD sub  70  is operationally connected at the lower end to the TPS  12  and at the upper end to the connector head  13 . The LWD/MWD sub  70  comprises one or more sensors (not shown). The hybrid tool is preferably used to depth correlate previously measured LWD/MWD data with measurements obtained with the wireline conveyance system  100 . 
   Operation of the hybrid system shown in  FIG. 3  is illustrated with an example. Assume that neutron porosity and gamma ray LWD/MWD logs have been run previously while drilling the borehole. After completion of the LWD/MWD or “first” run, the drill string is removed from the borehole and the drill bit and motor or rotary steerable is removed. The wireline conveyance system  100 , comprising a gamma ray sensor and as an example a wireline formation tester, is added to the tool string below the LWD/MWD sub  70 , as shown in  FIG. 3 . The tool string is lowered into the borehole, and the wireline tool  40  (comprising the gamma ray sensor and formation tester) is deployed as illustrated in  FIG. 3 . The tool string is moved up the borehole as indicated by the arrow  66  thereby forming a “second” run with the tools “sliding”. 
   Both the wireline tool  40  and the LWD/MWD sub  70  measure gamma radiation as a function of depth thereby forming LWD/MWD and wireline gamma ray logs. It known in the art that multiple detectors are typically used in logging tools to form count rate ratios and thereby reduce the effects of the borehole. It is also known that additional borehole corrections, such as tool standoff corrections, are typically applied to these multiple detector logging tools. As an example, standoff corrections are applied to dual detector porosity and dual detector density systems. Standoff corrections for rotating dual detector tools typically differ from standoff corrections for wireline tools. The LWD/MWD neutron porosity measurement is preferably not repeated in the second run, since LWD/MWD borehole compensation techniques, including standoff, are typically based upon a rotating, rather than a sliding tool. Furthermore, washouts and drilling fluid invasion tends to be more prevalent during the second run. Stated another way, the neutron porosity measurement would typically be less accurate if measured during the second run, for reasons mentioned above. 
   The second run LWD/MWD gamma ray log may not show the exact magnitude of response as the “first run” LWD/MWD log, because factors discussed above in conjunction with the neutron log. Variations in the absolute readings tend to be less severe than for the neutron log. Furthermore, the second run gamma ray log shows the same depth correlatable bed boundary features as observed during the first run. 
   During the second run, the tool string is stopped at desired depths to allow multiple formation tests. Formation testing results, made with the wireline tool  40  during the second run, are then depth correlated with neutron porosity, made with the LWD/MWD sub  70  during the first run made while drilling, by using the gamma ray logs made during both runs as a means for depth correlation. All data are preferably telemetered to the surface via the telemetry link  22 . Alternately, the data can be recorded and stored within the wireline tool for subsequent retrieval at the surface of the earth. 
   The conveyance system  100  can be combined with an LWD/MWD system to enhance the performance of both technologies using alternate configurations and methodology.  FIG. 4   a  shows the LWD/MWD sub  70  operationally connected to the TPS sub  12 , which is terminated at the lower end by a drill bit  72 . One or more LWD/MWD measurements are made as the drill string  18  rotates and advances the borehole downward as indicated by the arrow  67 . This will again be referred to as the “first run”. 
   During a second run of the drill string such as a wiper trip, the WCS  10  is added to the drill string along with a wiper  17 , as shown in  FIG. 4   b.  In this embodiment, the WCS  10  and LWD/MWD sub  70  share the same power supply  52  and downhole telemetry unit  46  (see  FIGS. 2   a  and  2   b ) contained in the TPS  12 . The tool is lowered to the desired depth, the wireline tool  40  is deployed as previously discussed, and the tool string in moved up the borehole (as indicated by the arrow  66 ) using the drill string  18  and cooperating connector head  13 . One or more wireline tool measurements along with at least one LWD/MWD correlation log are measured during this second run. The at least one LWD/MWD correlation log allows all wireline and LWD/MWD logs to be accurately correlated for depth, and for other parameters such as borehole fluids, over the full extent of the logged interval. Again, all measured data are preferably telemetered to the surface via the telemetry link  22 . Alternately, the data can be recorded and stored within the borehole tool for subsequent retrieval at the surface of the earth. 
   It should be noted that the step of running at least one LWD/MWD correlation log can be omitted, and only a wireline log using the tool  40  can be run if the particular logging operation does not require a LWD/MWD log, or does not require LWD/MWD log and wireline log depth correlation. 
   It should also be noted that the downhole element discussed previously can contain a downhole processor thereby allowing some or all sensor responses to be processed downhole, and the “answers” are telemetered to the surface via the telemetry link  22  in order to conserve bandwidth. 
   While the foregoing disclosure is directed toward the preferred embodiments of the invention, the scope of the invention is defined by the claims, which follow.