WO2009067373A2

WO2009067373A2 - Generating and updating true vertical depth indexed data and log in real time data acquisition

Info

Publication number: WO2009067373A2
Application number: PCT/US2008/083320
Authority: WO
Inventors: Xuejun Yang; Kanai Pathak
Original assignee: Schlumberger Canada Limited; Services Petroliers Schlumberger; Schlumberger Holdings Limited; Schlumberger Technology B.V.; Prad Research And Development Limited
Priority date: 2007-11-21
Filing date: 2008-11-13
Publication date: 2009-05-28
Also published as: CA2706309A1; GB2467253A; WO2009067373A3; GB201007621D0; US20090132168A1; NO20100705L

Abstract

An invention for dynamically determining a trajectory of a drilled wellbore is provided. A method may include: receiving a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and updating only a portion of the determined trajectory, a calculation of the portion of the determined trajectory being affected by the received data.

Description

GENERATING AND UPDATING TRUE VERTICAL DEPTH INDEXED DATA AND LOG IN REAL TIME DATA ACQUISITION

FIELD OF THE INVENTION

[0001] The present invention relates generally to data analysis in wellbore drilling and more specifically to dynamically determining a trajectory of a drilled wellbore.

BACKGROUND OF THE INVENTION

[0002] During D&M or Wireline data acquisition, a large volume of time stamped data is generated over a depth interval. The data is then gated in real time into depth indexed data for further analysis, displaying in logs, and/or delivery to a client. Many kinds of data analyses such as temperature calculations use true vertical depth (TVD) indexed data instead of measured depth (depth) indexed data. TVD is one of two primary depth measurements used by the drillers, the other being measured depth. TVD refers to the vertical distance from a point in the wellbore (usually the current or final depth) to a point at the surface, usually the elevation of the rotary kelly bushing (RKB). TVDs are important in determining, for example, bottomhole pressures, which are caused in part by the hydrostatic head of fluid in the wellbore. For this calculation, measured depth is irrelevant and TVD must be used. Typically, if no designation is used to indicate which depth measurement it refers to, the term "depth" refers to a measured depth. Note that a measured depth, due to intentional or unintentional curves in the drilled wellbore, is usually longer than a TVD at any given point. [0003] It is highly desirable to transform depth indexed data into TVD indexed data in real time. Unlike the depth index values, which depend only on the drilling or logging direction, the TVD index values can change as the well trajectory gets enhanced with more accepted survey stations. However, converting depth indexed data into TVD indexed data (or converting measured depth into TVD) in real time presents a special challenge. In existing data acquisition systems, the real time TVD logs cannot be corrected once generated since the TVD index range cannot be updated and the depth indexed data are not re-gated over the changed TVD index range. As a consequence, for example, the TVD logs are not correctly updated after a survey station is accepted.

SUMMARY OF THE INVENTION

[0004] In one embodiment of the invention, there is a method for dynamically determining a trajectory of a drilled wellbore. In this embodiment, the method comprises: receiving a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and updating only a portion of the determined trajectory, a calculation of the portion of the determined trajectory being affected by the received data.

[0005] In a second embodiment of the invention, there is a system for dynamically determining a trajectory of a drilled wellbore. In this embodiment, the system comprises: means for receiving a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and means for updating only a portion of the determined trajectory, a calculation of the portion of the determined trajectory being affected by the received data.

[0006] In a third embodiment of the invention, there is a computer program product for dynamically determining a trajectory of a drilled wellbore. In this embodiment, the computer program product comprises: computer usable program code stored in a computer useable medium, which, when executed by a computer system, enables the computer system to: receive a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and update only a portion of the determined trajectory, a calculation of the portion of the determined trajectory being affected by the received data.

[0007] Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention is illustrated by way of example and not intended to be limited by the figures of the accompanying drawings in which like references indicate similar elements and in which:

[0009] FIG. 1 shows a schematic block diagram of a system including a depth to TVD conversion tool according to one embodiment of this invention; [0010] FIG. 2 shows a flow chart describing a process of converting a depth into TVD according to one embodiment of this invention;

[0011] FIG. 3 shows examples of updating a trajectory of wellbore; and

[0012] FIG. 4 shows a computer environment which may be used to implement the depth to TVD conversion tool.

DETAILED DESCRIPTION

[0013] Advantages and features of the present invention may be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification. Embodiments of this invention are directed to a technique for dynamically converting measured depth to true vertical depth (TVD) and managing a cache for storing the dynamically updated TVD. Although the technique is described with reference to a measured depth of a drilled wellbore, the technique is suitable for use with any measured depth which deviates from the respective TVD.

[0014] Referring to FIG. 1, a schematic diagram of an illustrative system 10 for analyzing a wellbore 14 is shown. In FIG. 1, wellbore 14 is shown as a vertical well, but may also be other type of wells, such as a deviated well including a horizontal well. Wellbore 14 is shown as straight for simplicity but it is appreciated that actual wellbores may include curves such that a measured depth of a point in wellbore 14 is different (larger) than the respective TVD. Wellbore 14 is drilled in a reservoir 16 which may include any reservoir including but not limited to oil reservoir, gas reservoir, coal reservoir, and underground water reservoir. A measurement device(s) 20, e.g., a survey station, is positioned along wellbore 14 to obtain information (data) related to wellbore 14 or the drilling process, e.g., openhole log data. Measurement device 20 may be any solution to obtain the required information. In the description herein, "any solution" refers to any currently known or later developed technique to achieve a goal. For example, measurement device 20 may include portable rotary torque meters, weight indicators, log devices, sink probes, observation probe, and/or the like. As drill string or tool string, which is composed of one or more tools each tool having one or more measurement devices 20, drills further into reservoir formation 24 of reservoir 16, measurement devices 20 may be positioned further with the progress of drillstring. A progress of wellbore 14 refers to the extension of wellbore 14 to the bottom thereof. As is appreciated, measurement devices 20 may be positioned along wellbore 14 and/or may proceed into wellbore 14. FIG. 1 shows that measurement devices 20(a)-(d) are positioned in earth formation 24 of reservoir 16 for clarity, which is not necessary. Measurement device 20 may be positioned within wellbore 14.

[0015] Information obtained by measurement device 20 is communicated to a processing center 22 via any communication solution. Processing center 22 includes a depth to TVD conversion tool 24 ("TVD conversion tool 24"). Conversion tool 24 includes a data receiving component 26; a displaying component 28; a calculation component 30; a TVD conversion component 32; and a cache management component 34.

[0016] Data receiving component 26 is configured to receive information from either outside or inside of TVD conversion tool 24 (or both). In addition, data receiving component 26 also includes an application programming interface (API) which functions to convert received data or information into a format that can be used by TVD conversion tool 24. For example, the information received from measurement devices 20 may represent the physical characteristics of drilled wellbore 14 and API may need to convert the physical characteristics into data (format) that is recognized by TVD conversion tool 24.

[0017] Displaying component 28 functions to display the operation progress, status, and/or results of TVD conversion tool 24 as output(s) 42 to an outside individual (human-being or machine), e.g., a user 44, which in turn may use the information to, e.g., manage the drilling of wellbore 14 through instruction(s) 46.

[0018] Calculation component 30 is configured to calculate a trajectory of drilled wellbore 14 based on information received by data receiving component 26. Calculation component 30 may also function to convert a depth of drilled wellbore 14 into a TVD based on, e.g., the calculated trajectory of drilled wellbore 14. Calculation component 30 may apply any now know or later developed technique in the calculation thereby.

[0019] Cache management component 34 functions to manage a cache to temporarily store a calculated trajectory of drilled wellbore 14 and/or a TVD of a point therein. Basically, cache management component 34 may manage the cache based on a result of the calculation by calculation component 30 and other related information. For example, the factor that triggers the updating of wellbore 14 trajectory may be considered by cache management component 34 in updating the cache.

[0020] FIG. 2 shows a flow chart describing a process 100 of dynamically determining a true vertical depth of a point in wellbore 14 according to embodiments of this invention. As shown in FIG. 2, the process 100 begins at process block 110 where data receiving component 26 receives information which is relevant to determining a trajectory of drilled wellbore 14. Specifically, data receiving component 26 receives from measurement devices 20 physical characteristics of wellbore 14 and may convert the measured physical characteristics into data acceptable/usable by TVD conversion tool 24.

[0021] At process block 120, calculation component 30 calculates/updates a portion of the calculated trajectory of drilled wellbore 14. Specifically, only the portion of the calculated trajectory that is affected by the newly received data will be updated. For different types of data, the affected portion of the traj ectory will be different. Consequently, calculation component 30 may only need to calculate/update the respective portion(s) of trajectory of drilled wellbore 14. FIG. 3 shows examples of received data and updated portions of the trajectory.

[0022] In FIG. 3, blocks 200 (200a, 200b, 200c shown, enclosed in a dotted block for clarity) indicate different events (example) that cause update of information regarding drilled wellbore 14, and blocks 210 (210a, 210b, 210c shown) indicate portions of the trajectory affected by the data and thus updated by calculation component 30. At block 200a, a Tie-in-Point (TIP) for calculating the trajectory of wellbore 14 is updated/ modified. Consequently, in the respective block 210a, the entire trajectory will be recalculated as the Tie-in-Point affects the entire trajectory. At block 200b, a new (first) measurement device 20, e.g., a survey station, is accepted, which obtains new information regarding physical characteristics of drilled wellbore 14. In this case, at the respective block 210b, the trajectory will be updated from another (second) measurement device 20 positioned immediately above the newly accepted (first) measurement device 20 along a progress of wellbore 14. That is, the updated portion of the trajectory extends from the (second) measurement device 20 positioned immediately above the newly accepted (first) measurement device 20 to a deepest measurement device 20 positioned along the progress of wellbore 14. For example, with respect to FIG. 1, assuming measurement device 20b is a newly accepted measurement device 20, calculation component 30 will update/calculate the trajectory of wellbore 14 from measurement device 20a that is positioned immediately above measurement device 20b to measurement device 20c which is the deepest measurement device.

[0023] As shown in FIG. 3, within block 210b, calculation component 30 may further determine whether the newly accepted measurement device is positioned deepest along the progress of drilled wellbore 14. If the newly accepted measurement device is the deepest one, calculation component 30 may need to calculate the portion of the trajectory (from the immediately above measurement device 20) as the deepest measurement device 20 provides the updated progress of wellbore 14. If the newly accepted measurement device is not the deepest one, calculation component 30 may need to update the already calculated trajectory (from the immediately above measurement device 20), as the trajectory has already been calculated up to the deepest measurement device 20. In the description herein, updating the trajectory of wellbore 14 includes the situations of above mentioned updating and calculating operations of calculation component 30, unless specifically indicated otherwise.

[0024] In the description herein, the terms "deep" and "above" are defined with respect to the progress of the drilled wellbore 14. As such, in some situation, the "deepest" measurement device 20 may not necessarily have a higher TVD value than a measurement device portioned "above" the deepest measurement device 20.

[0025] Returning to FIG. 3, at block 200c, an already accepted (first) measurement device 20 is rejected. Consequently, at block 210c, the trajectory will be updated from another (second) measurement device 20 positioned immediately above the newly rejected (first) measurement device 20 along a progress of wellbore 14.

[0026] Returning to FIG. 2, at process block 130, TVD conversion component 32 converts a depth value of a point in the drilled wellbore to a true vertical depth (TVD) based on the calculated/updated trajectory of wellbore 14. Any now available or later developed technique may be used in the conversion, and none limits the scope of the invention.

[0027] At process block 140, cache management component 34 manages a cache storing the trajectory and/or the converted TVD based on the updating thereof. Cache management component 34 only updates a portion of a cache corresponding to the updated trajectory of wellbore 14 and/or the updated TVD of a point of wellbore 14. For example, turning to FIG. 3 to follow the previous example, at block 220a, a cache will be generated/ regenerated to store the calculated trajectory as the entire trajectory is recalculated at block 210a. At block 220b, cache management component 34 updates/calculates a portion of the cache corresponding to the updated/calculated portion of the trajectory of wellbore 14 resulted from block 210b. Similarly at block 220c, cache management component 34 updates/calculates a portion of the cache corresponding to the updated portion of the trajectory of wellbore 14 due to the rejection of measurement device 20b.

[0028] An alternate embodiment of the invention is as follows. A computer system is created is created acording to Figure 3. It is initialized with the survey data and is responsible for all the trajectory related calculations. For example, it can calculate the corresponding TVD index value for any given depth index value at any time.

[0029] A client initializes the process by providing survey data to be processed. The survey data includes a collection of accepted survey stations. Each accepted survey station contains the measured depth, inclination from the vertical, azimuth from the north, TVD, north displacement, east displacement, and other related values. A TIP is entered by the field engineer. The TIP has the shallowest depth and TVD values (usually at the surface) and is used to tie all the other accepted stations together during trajectory calculations. The computer system keeps track of all the survey related data and uses the survey data to keep the well trajectory up to date at all times. The well trajectory is calculated as follows: 1. Sort all the accepted survey stations by increasing station depth values with the TIP at the top (shallowest depth).

2. For any depth value between the TIP and the deepest station depth value, use the well known minimum curvature algorithm to calculate its other values such as TVD. i. Find the enclosing shallower and deeper accepted stations, ii. Interpolate the values by using the enclosing shallower and deeper accepted stations' values.

For any depth value deeper than the deepest accepted station depth, use straight line extrapolation to calculate the other values.

[0030] The calculation component 30 (Fig.2) or blocks 200 (Fig.3) observe any changes in the station data. If a new survey station is accepted or an accepted survey station is rejected, block 200b automatically re-sorts the accepted survey stations and updates the trajectory to reflect the changes.

[0031] The output of the computer system is a representation of the TVD indexed data. It specifies the data type, TVD index start and stop index values, the TVD index step size (sampling rate), the cardinality which is the number of points, and other information. It provides TVD indexed data access to the client in a transparent manner.

[0032] The client requests for TVD for a depth representation object by supplying the depth representation as the source data. The depth representation object is a representation of the depth indexed data. Just like the TVD representation, it specifies the data type, depth start and stop index values, the depth index step size, the cardinality which is the number of points, and other information.

[0033] The system responds by creating a TVD representation instance if an existing one originated from the same depth representation is not found. The newly- created TVD representation has the same data type and step size as the source depth representation and the TVD representation keeps a back pointer to the depth representation for access to the depth data. The TVD representation object also keeps a pointer to a cache in block 220 for any depth and TVD index conversions.

[0034] The TVD representation object then initializes itself. It first fetches the depth index range from its source depth representation object. It then gets the TVD index range from block 220 corresponding to the depth index range. Finally, it calculates the number of TVD data points with the formula: Number of TVD data points = absolute value (TVD stop index - TVD start index) / TVD step size. The TVD representation is then provided to the client.

[0035] The client can then use the returned TVD representation object to fetch the TVD indexed data. The client can first ask the TVD representation object for its cardinality which represents the number of TVD points as calculated above. Using the cardinality value, it can then loop through to get some or all of the TVD index and data values. [0036] The TVD index values are directly calculated and returned with the formula: TVD Index = TVD start index + i * TVD step size where O <= i < TVD cardinality is the zero-based TVD ordinal number.

[0037] The TVD data value for a given TVD index value is found by block 220 and then getting its corresponding depth data value from the source depth representation object.

[0038] As the real time drilling or logging job goes on, the client periodically calls the TVD representation's refresh method to update the TVD index values and ranges dynamically. The TVD representation forwards its refresh call to the block 220 refresh method, which performs the actual TVD index range updates.

[0039] Block 220 performs all the depth index to TVD index and TVD index to depth index conversions and keeps track of them in its internal cache. When an open survey station is accepted or an accepted survey station is rejected, the cache is invalidated and rebuilt as needed. As the depth index range changes during logging or drilling, the internal cache is updated to reflect the new depth index range.

[0040] The foregoing flow chart shows some of the processing functions associated with preparing an electronic document of a log containing continuous information for both continuous and page-by-page printing according to one embodiment of this invention. In this regard, each block represents a process act associated with performing these functions. It should also be noted that in some alternative implementations, the acts noted in the blocks may occur out of the order noted in the figure or, for example, may in fact be executed substantially concurrently or in the reverse order, depending upon the act involved. Also, one of ordinary skill in the art will recognize that additional blocks that describe the processing functions may be added.

[0041] FIG. 4 depicts a block diagram of a general-purpose computer system 300 that can be used to implement data correction tool 300. Data correction tool 300 may be coded or deployed as a set of instructions on removable or hard media for use by the general-purpose computer 300. The computer system 300 has at least one microprocessor or central processing unit (CPU) 305. The CPU 305 is interconnected via a system bus 320 to machine readable media 375, which includes, for example, a random access memory (RAM) 310, a read-only memory (ROM) 315, a removable and/or program storage device 355, and a mass data and/or program storage device 350. An input/output (I/O) adapter 330 connects mass storage device 350 and removable storage device 355 to system bus 320. A user interface 335 connects a keyboard 365 and a mouse 960 to the system bus 320, a port adapter 325 connects a data port 345 to the system bus 320, and a display adapter 340 connects a display device 370 to the system bus 320. The ROM 315 contains the basic operating system for computer system 300. Examples of removable data and/or program storage device 355 include magnetic media such as floppy drives, tape drives, portable flash drives, zip drives, and optical media such as CD ROM or DVD drives. Examples of mass data and/or program storage device 350 include hard disk drives and non-volatile memory such as flash memory. In addition to the keyboard 365 and mouse 960, other user input devices such as trackballs, writing tablets, pressure pads, microphones, light pens and position-sensing screen displays may be connected to user interface 335. Examples of the display device 370 include cathode-ray tubes (CRT) and liquid crystal displays (LCD).

[0042] A machine readable computer program may be created by one of skill in the art and stored in computer system 300 or a data and/or any one or more of machine readable medium 375 to simplify the practicing of this disclosure. In operation, information for the computer program created to run the present disclosure is loaded on the appropriate removable data and/or program storage device 355, fed through data port 345, or entered using keyboard 365. A user controls the program by manipulating functions performed by the computer program and providing other data inputs via any of the above mentioned data input means. The display device 370 provides a way for the user to accurately control the computer program and perform the desired tasks described herein.

[0043] Computer readable media can be any available media that can be accessed by a computer. By way of example, and not limitation, computer readable media may comprise "computer storage media" and "communications media."

[0044] "Computer storage media" include volatile and non- volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. [0045] "Communication media" typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as carrier wave or other transport mechanism. Communication media also includes any information delivery media.

[0046] The term "modulated data signal" means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above are also included within the scope of computer readable media.

[0047] While shown and described herein as a method and system for performing a data correction on a hierarchical integrated circuit layout, it is understood that the disclosure further provides various alternative embodiments. For example, in an embodiment, the disclosure provides a program product stored on a computer- readable medium, which when executed, enables a computer infrastructure to perform a data correction on a hierarchical integrated circuit layout. To this extent, the computer-readable medium includes program code, such as data correction tool 300 (FIG. 4), which implements the process described herein. It is understood that the term "computer-readable medium" comprises one or more of any type of physical embodiment of the program code.

[0048] It should be appreciated that the teachings of the present disclosure could be offered as a business method on a subscription or fee basis. For example, a computer system comprising data correction tool 300 (FIG. 4) could be created, maintained and/or deployed by a service provider that offers the functions described herein for customers. That is, a service provider could offer to provide a service to perform a data correction on a hierarchical IC layout as described above.

[0049] As used herein, it is understood that the terms "program code" and "computer program code" are synonymous and mean any expression, in any language, code or notation, of a set of instructions that cause a computing device having an information processing capability to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and/or (c) decompression. To this extent, program code can be embodied as one or more types of program products, such as an application/software program, component software/a library of functions, an operating system, a basic I/O system/driver for a particular computing and/or I/O device, and the like. Further, it is understood that the terms "component" and "system" are synonymous as used herein and represent any combination of hardware and/or software capable of performing some function(s).

[0050] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. [0051] Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the disclosure has other applications in other environments. This application is intended to cover any adaptations or variations of the present disclosure. The following claims are in no way intended to limit the scope of the disclosure to the specific embodiments described herein.

[0052] It is apparent that there has been provided by this invention an approach for performing data correction operation on an IC layout accommodating compensation for CD variations. While the invention has been particularly shown and described in conjunction with a preferred embodiment thereof, it will be appreciated that variations and modifications will occur to those skilled in the art. Therefore, it is to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

We claim:

1. A method for dynamically determining a trajectory of a drilled wellbore, comprising:

receiving a piece of information including data converted from a measured physical characteristic of at least one of a wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and

updating only a portion of the piece of information relevant to the determined traj ectory, a calculation of the portion being affected by the received data.

2. The method according to claim 1, wherein the measured physical characteristic is provided by a first measurement device.

3. The method according to claim 2, wherein the portion is calculated from a second measurement device positioned above the first measurement device along a progress of the wellbore to a deepest measurement device positioned along the progress of the wellbore.

4. The method according to claim 1 , wherein the piece of information indicates that a previously accepted measurement device is rejected.

5. The method according to claim 4, wherein the portion is calculated from a measurement device positioned above the rejected previously accepted measurement device along a progress of the wellbore to a deepest measurement station positioned along the progress of the wellbore.

6. The method according to claim 1, further comprising updating a provided cache storing the determined trajectory with only the updated portion of the trajectory.

7. The method according to claim 1, wherein where the piece of information indicates a modification of a tie-in point for the determination of the trajectory, the updating includes calculating the entire trajectory.

8. The method according to claim 7, further comprising generating a cache for the calculated entire trajectory.

9. The method according to claim 1, further comprising calculating and updating a true vertical depth of a point of the wellbore based on the determined trajectory.

10. A system for dynamically determining a trajectory of a drilled wellbore, comprising:

means for receiving a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and

means for updating only a portion of the information relevant to determining a traj ectory, a calculation of the portion of being affected by the received data.

11. The system according to claim 10, wherein the physical characteristic is provided by a first measurement device.

12. The system according to claim 11, wherein the updating means calculates the portion from a second measurement device positioned above the first measurement device along a progress of the wellbore to a deepest measurement device positioned along the progress of the wellbore.

13. The system according to claim 10, wherein the piece of information indicates that a previously accepted measurement device is rejected.

14. The system according to claim 13, wherein the updating means calculates the portion from a measurement device positioned above the rejected previously accepted measurement device along a progress of the wellbore to a deepest measurement station positioned along the progress of the wellbore.

15. The system according to claim 10, further comprising means for updating a provided cache storing the determined trajectory with only the updated portion.

16. The system according to claim 10, wherein where the piece of information indicates a modification of a tie-in point for the determination of the trajectory, the updating means calculates the entire trajectory.

17. The system according to claim 16, further comprising means for generating a cache for the calculated entire trajectory.

18. The system according to claim 10, further comprising means for calculating and updating a true vertical depth of a point of the wellbore based on the determined trajectory.

19. A computer program product for dynamically determining a trajectory of a drilled wellbore, comprising: computer usable program code stored in a computer useable medium, which, when executed by a computer system, enables the computer system to:

receive a piece of information including data converted from a measured physical characteristic of at least one of the wellbore or drilling the wellbore, the piece of information being relevant to determining a trajectory of the wellbore; and

update only a portion of the information relevant to the determined trajectory, a calculation of the portion being affected by the received data.

20. The program product according to claim 19, wherein the data indicating a change of the physical characteristic related to a first measurement device, and the portion is calculated from a second measurement device positioned immediately above the first measurement device along a progress of the wellbore to a deepest measurement device positioned along the progress of the wellbore.

21. A method for converting depth indexed data into true vertical depth indexed data in a wellbore comprising:

providing depth indexed data from a plurality of survey stations along the wellbore;

receiving a piece of information including data converted from a measured physical characteristic of each of the plurality of survey stations, the piece of information being relevant to determining a trajectory of the wellbore;

updating only a portion of the information relevant to the determined traj ectory from each of the plurality of survey stations, a calculation of the portion of being affected by the received data;

calculating and updating a true vertical depth for each of the survey stations of the wellbore based on the updated portion; and

providing true vertical depth indexed data for the plurality of survey stations along the wellbore.