Patent Publication Number: US-11378716-B2

Title: Method for altering locations of survey measurements along a borehole so as to increase measurement density

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application which claims priority from U.S. utility application Ser. No. 15/476,107, filed Mar. 31, 2017, which is a nonprovisional application which claims priority from U.S. provisional application No. 62/316,411, filed Mar. 31, 2016. 
    
    
     TECHNICAL FIELD/FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to downhole measurement tools, and specifically to methods of operating downhole measurement tools. 
     BACKGROUND OF THE DISCLOSURE 
     Knowledge of wellbore placement and surveying is useful for the development of subsurface oil &amp; gas deposits, mining, and geothermal energy development. Accurate knowledge of the position of a wellbore at a measured depth, including inclination and azimuth, may be used to attain the geometric target location of, for example, an oil bearing formation of interest. Additionally, accurate relative placement of a wellbore to a geological zone or formation, or relative to one or more adjacent wellbores, may be useful for the production or hydrocarbons or geothermal energy. Additionally, knowledge of the formation properties surrounding a wellbore along its depth may be used to guide wellbore placement into desired geological features or zones. Traditionally a combination of sensors are deployed on a drill string to measure these properties. 
     The measurement of inclination and azimuth of the wellbore may be used in surveying operations. Inclination is the angle between the longitudinal axis of a wellbore or a drill string or other downhole tool positioned in a wellbore and the Earth&#39;s gravity vector, and azimuth is the angle between a horizontal projection of the longitudinal axis and north, whether measured by a magnetometer (magnetic north) or by a gyro (true north). In some instances, surveying operations may include estimating the distance, orientation, or both the distance and orientation of a borehole relative to other boreholes by measuring the magnetic field that is produced either passively from the adjacent wellbore&#39;s casing or drill pipe, or by measuring an actively generated magnetic field. 
     One method of determining the orientation and position of a downhole tool with respect to the Earth spin vector is to take a gyro survey, referred to herein as a gyrocompass, to determine a gyro toolface, inclination, and azimuth. The gyrocompass utilizes one or more gyroscopic sensors, referred to herein as gyros to detect the Earth&#39;s rotation and determine the direction to true north from the downhole tool, the reference direction for a gyro toolface and azimuth. 
     The determination of orientation, position, inclination, and azimuth of the downhole tool may include determining a gravity toolface or magnetic toolface by using one or more accelerometers or magnetometers respectively. Accelerometers may be used to detect the local gravity field, typically dominated by the Earth&#39;s gravity, to determine the direction to the center of the Earth. This direction may be used as the reference direction for a gravity toolface. Magnetometers may similarly be used to detect the local magnetic field, typically dominated by the Earth&#39;s magnetic field, to determine the direction to magnetic north. This direction may be used as the reference direction for a magnetic toolface. 
     These measurements, referred to herein as a survey, may be taken by a surveying tool positioned on a drill string. A drill string is typically made up of tubular segments joined end to end, which are built up or broken down on a drilling rig to increase or decrease respectively the overall length of the drill string during the drilling or completions process. Typically, tubular segments are joined in sections of two or three before being added to the drill string, or are removed in sets of two or three, referred to herein as a pipe stand. While the pipe stand is joined to or removed from the drill string, the drill string containing the survey or LWD tool may typically be held relatively stationary. These conditions during the joining and removal process may be ideal for making survey or logging while drilling (LWD) measurements. 
     SUMMARY 
     The present disclosure provides for a method. The method may include providing a drill string including a measurement tool. The drill string may be positioned in a wellbore. The method may include taking a measurement with the measurement tool at a first location. The method may include coupling a pipe stand including a first selected number of tubular segments to the drill string, the first selected number being two or more. The method may include lowering or advancing the drill string into the wellbore the length of the pipe stand. The method may include taking a measurement with the measurement tool at a second location. The method may include raising the drill string the length of a tubular segment. The method may include removing a second selected number of tubular segments from the drill string, the second selected number different from the first selected number. The method may include taking a measurement with the measurement tool at a third location. The method may include raising the drill string the length of the first selected number of tubular segments. The method may include removing the first selected number of tubular segments. The method may include taking a measurement with the measurement tool at a fourth location. 
     The present disclosure also provides for a method. The method may include providing a drill string. The drill string may include a measurement tool. The drill string may be positioned in a wellbore. The method may include taking a measurement of the wellbore with the measurement tool at a first location. The method may include removing a pipe stand including a first selected number of tubular segments from the drill string, the first selected number being two or more. The method may include raising the drill string the length of the pipe stand. The method may include taking a measurement of the wellbore with the measurement tool at a second location. The method may include adding a second selected number of tubular segments to the drill string, the second selected number different from the first selected number. The method may include lowering the drill string the length of the second selected number of tubular segments. The method may include taking a measurement of the wellbore with the measurement tool at a third location. The method may include adding a pipe stand to the drill string, the pipe stand including the first selected number of tubular segments. The method may include lowering the drill string the length of the pipe stand. The method may include taking a measurement of the wellbore with the measurement tool at a fourth location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  depicts a portion of a measurement operation consistent with at least one embodiment of the present disclosure. 
         FIG. 2  depicts a portion of a measurement operation consistent with at least one embodiment of the present disclosure. 
         FIG. 3  depicts a portion of a measurement operation consistent with at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     As depicted in  FIG. 1 , drill string  100  may be positioned in wellbore  10 . Wellbore  10  may extend into Earth  15  from surface  20 . Drill string  100  may be manipulated by drilling rig  25 , which may have apparatuses to rotate drill string  100  as wellbore  10  is formed in Earth  15 . In certain embodiments, drilling rig  25  may be a workover rig. In some embodiments, drilling rig  25  may include hoisting apparatuses such as drawworks  30  and traveling block  35 . 
     In some embodiments, drill string  100  may include measurement tool  101 . Measurement tool  101  may be a survey tool or any measurement while drilling (MWD) or logging while drilling tool (LWD). Example LWD tools may include, but are not limited, to resistivity, porosity, natural gamma detectors, spectral gamma detectors, and borehole calipers. Example MWD tools may include sensors that measure the earth&#39;s inclination and azimuth, such as survey tools. 
     Measurement tool  101  may include one or more sensors such as, for example and without limitation, magnetometers, accelerometers, or gyros. Measurement tool  101  may, for example and without limitation, be used to make measurements within wellbore  10  as drill string  100  is inserted into or removed from wellbore  10 . Although depicted as being at an end of drill string  100 , one having ordinary skill in the art with the benefit of this disclosure will understand that measurement tool  101  may be positioned at any point along drill string  100  without deviating from the scope of this disclosure. 
     As understood in the art, drill string  100  may be formed from a plurality of tubular segments  103  joined end to end. In some embodiments, tubular segments  103  may be sequentially added to drill string  100  as wellbore  10  is drilled or as drill string  100  is made up into wellbore  10 . In some embodiments, drill string  100  may thus be made up by lowering drill string  100  into wellbore  10  and adding one or more tubular segments  103  to drill string  100  with drilling rig  25 . The lowering and adding operations may be repeated until drill string  100  has extended a desired length into wellbore  10 . In some embodiments, a first preselected number of previously joined tubular segments  103 , depicted in  FIG. 1  as pipe stands  105  including three tubular segments  103 , may be added to drill string  100  at each step. Pipe stands  105  may be made up prior to forming drill string  100 . The first preselected number of tubular segments  103  may be any number, two or more, of tubular segments  103  capable of being handled by drilling rig  25  as understood in the art. 
     In some embodiments, as drill string  100  is tripped or lowered into the wellbore  10  or as the wellbore  10  advances due to the drilling process, measurement tool  101  may be used to take a measurement of wellbore  10  during the time in which drill string  100  is stopped as the next pipe stand  105  is added. Measurements may thus be taken at a first set of measurement locations  107  as depicted in  FIGS. 1-3  as drill string  100  is inserted into wellbore  10 . Thus, for example and without limitation, in an embodiment in which pipe stands  105  consist of multiples of three tubular segments  103 , measurement locations  107  may be evenly spaced in wellbore  10  at a distance corresponding to the length of three tubular segments  103 . 
     In some embodiments, drill string  100  may be tripped out of wellbore  10  by raising drill string  100  by drilling rig  25  and removing one or more tubular segments  103  from drill string  100  at drilling rig  25 . In some embodiments, during the tripping out operation, a second preselected number of tubular segments  103  may be removed from drill string  100  different from the first preselected number of tubular segments  103  which were added to make up drill string  100 . The second preselected number of tubular segments  103  may be any number of tubular segments  103  which is different from the first preselected number of tubular segments  103 . For example and without limitation, as depicted in  FIG. 2 , a single tubular segment  103 ′ may be removed from drill string  100 . Subsequently, a measurement may be taken with measurement tool  101  at modified measurement location  109 . In other embodiments, as understood in the art, two tubular segments  103  may be removed without deviating from the scope of this disclosure in a case where pipe stands  105  are three tubular segments  103  in length. 
     Drill string  100  may then be tripped out of wellbore  10  by raising drill string  100  by drilling rig  25  and removing tubular segments  103  as pipe stands  105 ′ having the first preselected number of tubular segments  103  as depicted in  FIG. 3 . Measurement tool  101  may be used to take a measurement of wellbore  10  during the time in which each pipe stand  105 ′ is removed from drill string  100 . Measurements may thus be taken at a second set of measurement locations  107 ′ as depicted in  FIG. 3 . Measurement locations  107 ′ may thus be evenly spaced in wellbore  10  at a distance corresponding to the length of pipe stand  105 ′. Measurement locations  107 ′ may thus be offset from measurement locations  107  by the length of the second preselected number of tubular segments  103 ′ removed from drill string  100 . In an embodiment in which one tubular segment  103 ′ is removed as depicted in  FIG. 2 , measurement locations  107 ′ may be offset from measurement locations  107  by the length of one tubular segment  103 ′. Thus, this method may be utilized to increase measurement density along the length of a wellbore. 
     Measurements taken by measurement tool  101  at measurement locations  107  and measurement locations  107 ′ may be utilized to generate a model of wellbore  10 . Measurements taken by measurement tool  101  at measurement locations  107  and  107 ′ may be combined with other measurement or LWD information measured during drilling, such as continuous inclination and azimuth surveys, to generate a model of wellbore  10 . 
     In some embodiments, instead of removing a second preselected number of tubular segments  103 ′, the second preselected number of tubular segments  103 ′ may be added prior to the tripping out operation. In some embodiments, the second preselected number of tubular segments  103 ′ may be added or removed from drill string  100  before a tripping in operation. Although described as a tripping out and tripping in operation, one having ordinary skill in the art with the benefit of this disclosure will understand that the measurement operations described herein may be applied to a tripping in and tripping out operation without deviating from the scope of this disclosure. One having ordinary skill in the art with the benefit of this disclosure will understand that one need not measure during a trip in before measurement during a tripping out operation. 
     In some embodiments, a third preselected number of tubular segments  103  may be added to or removed from drill string  100  before a tripping in operation as described with respect to  FIG. 1  subsequent to the tripping out operation described with respect to  FIG. 3 . In such an embodiment, for example and without limitation, the first preselected number of tubular segments  103  used to form pipe stands  105  may be three, the second preselected number of tubular segments  103  added to or removed from drill string  100  may be one, and the third number of tubular segments  103  added to or removed from drill string  100  before the next trip in may be one or two. In an example in which each tubular segment  103  is 30 feet long, the first tripping in operation may result in measurement locations  107  being taken 90 feet apart, the tripping out operation may result in measurement locations  107 ′ being spaced 90 feet apart, offset 30 feet from measurement locations  107 , and the subsequent tripping in operation (not shown), may result in measurement locations being spaced 90 feet apart, offset 30 feet from measurement locations  107  and  107 ′. 
     By taking measurements as discussed herein, measurements may be taken at more measurement locations  107 ,  107 ′ and  109  along wellbore  10  than if taken only at the first preselected length of pipe stand  105 . By increasing the number of measurement locations  107 ,  107 ′, the data density of the measurements taken along wellbore  10 , i.e. the number of measurements taken per length of wellbore  10 , may be increased. The additional data density may, for example and without limitation, reduce error introduced when applying a curve-fitting algorithm or mathematical models such as minimum curvature or spline fits to determine the spatial model of wellbore  10  from the measurement points. 
     In some embodiments, additional measurement tools (not shown) may be positioned on drill string  100 . In some such embodiments, the additional measurement tools may be positioned spaced apart from measurement tool  101  a distance other than the first predetermined length of pipe stand  105  or the second predetermined length of tubular segment  103 ′. In some such embodiments, the additional measurement tools may provide additional measurement locations along wellbore  10  other than measurement locations  107 ,  107 ′, thus further increasing the data density gathered as discussed herein above. As described above, the measurement information may be utilized to generate a model of a wellbore  10 . 
     In some embodiments, measurements taken during the surveys may be stored to internal memory positioned in measurement tool  101 . In some embodiments, measurements taken during the measurement operations may be transmitted to a receiver (not shown) at surface  20 . In some such embodiments, measurements taken during the measurement operations may be transmitted by any suitable method known in the art including, for example and without limitation, by wireline, MWD telemetry, electromagnetic telemetry, or mud pulse telemetry. 
     The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.