Coring device

A coring device, comprising an electronic sub communicated with a ground control system and identifying the position of a core taken underground, a supporting arm sub for fixing the coring device, a rotating sub for rotating a mechanical sub to a specified position to carry out coring by rotating, a hydraulically controlled sub for providing power to the rotating sub and the mechanical sub, a mechanical sub for performing pushing, coring, core folding and core length measurement operations, and a core storage barrel sub for storing a taken core, which are sequentially connected. The rotating sub comprises a rotating shaft, a moving sleeve which sleeves the rotating shaft and is in threaded connection with the rotating shaft, and a fixed housing; the rotating shaft and the moving sleeve are arranged inside the fixed housing, two ends of the rotating shaft respectively extend from two ends of the fixed housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is a U.S. National Phase Entry of International Application PCT/CN2021/085835 having an international filing date of Apr. 7, 2021, which claims priority of Chinese patent application 202010737790.7, filed on Jul. 28, 2020, and the contents disclosed in the above-mentioned applications are hereby incorporated as a part of this application.

TECHNICAL FIELD

Embodiments of the present application relate to, but are not limited to, the field of logging instruments, in particular to a coring instrument (device).

BACKGROUND

In some technologies of downhole coring operations, azimuth information of taken core is very important for a downhole heterogeneous formation, and meanings represented by the cores at different azimuths vary greatly, azimuths and fractures of cores are very important for geologists. However, coring instruments in some technologies are only able to complete the coring operations downhole, and cannot accurately identify the azimuth of the cores downhole, much less directly drill a core in a certain azimuth downhole.

SUMMARY

The following is a summary of the subject matters described in detail herein. This summary is not intended to limit the protection scope of the claims.

An embodiment of the present application provides a coring instrument that can identify the azimuth in which the instrument is located downhole and drill a core in a specified azimuth.

An embodiment of the application provides a coring instrument which includes an electronic sub, a support arm sub, a rotary sub, a hydraulic control sub, a mechanical sub and a core reserving drum sub which are connected in sequence.

The mechanical sub is configured to complete operations of thrusting, coring, core-breaking and core length measurement; the core reserving drum sub is configured to reserve a taken core; the electronic sub is configured to communicate with a ground control system and identify an azimuth of the core taken downhole; the rotary sub is configured to rotate the mechanical sub to a specified azimuth for rotary coring; the hydraulic control sub is configured to provide power for the rotary sub and the mechanical sub; the support arm sub is configured to fix a position of the coring instrument in the downhole.

The rotary sub includes a rotating shaft, a moving sleeve and a fixed shell, the moving sleeve is sleeved outside the rotating shaft and is in threaded connection with the rotating shaft; the rotating shaft and the moving sleeve are arranged in the fixed shell, and two ends of the rotating shaft extend out of two ends of the fixed shell respectively, and the rotating shaft is axially limited in the fixed shell; an end face of the fixed shell close to the hydraulic control sub is provided with an oil inlet, and the hydraulic control sub is configured to inject hydraulic oil into the fixed shell through the oil inlet to push the moving sleeve to move axially.

The coring instrument provided by the embodiment of the present application can accurately measure the azimuth of the instrument during coring, and adjust the azimuth of the coring instrument according to the azimuth, to drill the core at the desired azimuth. After the coring instrument of the embodiment of the present application completes coring, relevant personnel (such as geologists) analyze the core, figure out the porosity, the permeability and the saturation of the formation, which together with the azimuth information of the core, may make the analyzed formation data be more accurate, provide more effective information for reservoir evaluation and greatly enhance the utilization value of the taken core.

Other features and advantages of the present application will be described in the following specification, and other aspects will become apparent upon reading and understanding of the drawings and detailed description.

DESCRIPTION OF REFERENCE SIGNS

DETAILED DESCRIPTION

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings. The embodiments in the present application and the features in the embodiments may be combined with each other randomly if there is no conflict.

An embodiment of the present application provides a coring instrument83, as shown inFIG.1, the coring instrument83includes an electronic sub1, a support arm sub2, a rotary sub3, a hydraulic control sub4, a mechanical sub5and a core reserving drum sub6which are connected in sequence.

The mechanical sub5is configured to complete operations of thrusting, coring, core-breaking (i.e., breaking a core) and core length measurement. The core reserving drum sub6is configured to reserve a taken core. The electronic sub1is configured to communicate with a ground control system81, and identify an azimuth of a core taken downhole, and may also be configured to control actions of the support arm sub2, the hydraulic control sub4, the rotary sub3and the mechanical sub5. The rotary sub3is configured to rotate the mechanical sub5to a specified azimuth for rotary coring. The hydraulic control sub4is configured to provide power for the rotary sub3and the mechanical sub5. The support arm sub2is configured to fix a position of the coring instrument83downhole.

As shown inFIG.3, the rotary sub3includes a rotating shaft31, a moving sleeve32and a fixed shell33. The moving sleeve32is sleeved outside the rotating shaft31and is in threaded connection with the rotating shaft31. The rotating shaft31and the moving sleeve32are arranged in the fixed shell33, and two ends of the rotating shaft31extend out of two ends of the fixed shell33respectively, and the rotating shaft31is axially limited in the fixed shell33. An end face of the fixed shell33close to the hydraulic control sub4is provided with an oil inlet, and the hydraulic control sub4is configured to inject hydraulic oil into the fixed shell33through the oil inlet to push the moving sleeve32to move axially.

As shown inFIG.2, the coring instrument83goes downhole to work, and the ground control system81may be arranged on the ground, the ground control system81may be configured to be able to receive commands, send commands, collect and process data, etc., and provide a control power supply and a power supply. The ground control system81may include a ground operation control panel, a large motor DC power, a small motor DC power, a ground monitoring industrial personal computer, a generator, a collector ring and other electric control accessories, etc. The ground control system81runs the coring instrument83into the well through an intermediate transmission device82for logging operation.

In the coring instrument83, the mechanical sub5is configured to complete operations of thrusting, coring, core-breaking and core length measurement. The core reserving drum sub6is configured to reserve a taken core. The electronic sub1is configured to communicate with the ground control system81, the electronic sub1can receive instructions sent by the ground control system81, and command the downhole instrument to complete a series of coring actions according to requirements of the instructions transmitted by the control system, also can collect an instrument status of the mechanical sub5for reference by the operator. The rotary sub3is configured to rotate the mechanical sub5to a specified azimuth for rotary coring. The hydraulic control sub4is configured to provide power for the rotary sub3, and the support arm sub2is configured to fix the position of the coring instrument83downhole. Only after the downhole position of the coring instrument83is fixed and an upper structure of the rotary sub3(an end of the rotary sub3away from the hydraulic control sub4) is fixed, the rotary operation can be carried out.

The hydraulic oil may be injected into the fixed shell33, and the moving sleeve32is pushed by the pressure of the high-pressure hydraulic oil to move axially. Since the moving sleeve32is in threaded connection with the rotating shaft31, the moving sleeve32may drive the rotating shaft31to rotate while moving axially, thus controlling the rotation of the lower mechanical sub5through the rotating shaft31.

In an exemplary embodiment, as shown inFIG.3, the oil inlet includes a first oil inlet334and a second oil inlet335, the moving sleeve32is in dynamic seal with the fixed shell33, and a sealed first cavity71and a sealed second cavity72are formed on two sides of the moving sleeve32, the first oil inlet334communicates with the first cavity71and the second oil inlet335communicates with the second cavity72.

Taking the example shown inFIG.3, when the hydraulic oil is injected into the first cavity71through the first oil inlet334, the moving sleeve32is pushed to move towards the left and the rotating shaft31rotates forward, when the hydraulic oil is injected into the second cavity72through the second oil inlet335, the moving sleeve32is pushed to move towards the right and the rotating shaft31rotates backward. When the rotating shaft31rotates forward or backward, it is possible to drive the mechanical sub5to rotate correspondingly, so as to drill the core in the desired azimuth.

In an exemplary embodiment, as shown inFIG.3, the fixed shell33includes a sleeve331, a fixed flange332and a fixed sleeve333, the fixed flange332and the fixed sleeve333are respectively arranged at two ends of the sleeve331along the axial direction, and the fixed flange332and the fixed sleeve333are each provided with a through hole for the rotating shaft31to pass therethrough.

Taking the example shown inFIG.3, the sleeve331, the fixed flange332and the fixed sleeve333form a cylindrical structure with through holes at both ends, both the rotating shaft31and the moving sleeve32are arranged in the cylindrical structure, and two ends of the rotating shaft31each extend out of the through holes provided on the fixed flange332and the fixed sleeve333, so as to be connectable to other structures at both ends. In order to improve the sealing performance of the connection, there are O-shaped seal rings provided between the sleeve331and the fixed sleeve333and between the sleeve331and the fixed flange332, respectively, the embodiment of the present application does not limit the forms of sealing between the sleeve331and the fixed sleeve333, and between the sleeve331and the fixed flange332.

In an exemplary embodiment, as shown inFIG.3, the outer side of the fixed sleeve333on the rotating shaft31, that is, a side of the fixed sleeve333away from the sleeve331is provided with a rotating disk34. The rotating disk34may be provided with a through hole, and the rotating shaft31may extend out of the through hole of the rotating disk34.

The rotating shaft31may be connected to other instrument string members through the rotating disk34.

In an exemplary embodiment, the first oil inlet334and the second oil inlet335are provided on the fixed flange332.

The first oil inlet334may directly communicate with the first cavity71. The second oil inlet335may communicate with the second cavity72through a channel73provided on the sleeve331.

In an exemplary embodiment, the rotating shaft31is provided with a first limiting part311, one end of the first limiting part311abuts against the fixed sleeve333, a retaining ring is installed on the sleeve331and abuts against the other end of the first limiting part311. Alternatively, as shown inFIG.3, the rotating shaft31is further provided with a second limiting part312, and the second limiting part312abuts against the fixed flange332.

It is possible to fix and limit an axial position of the rotating shaft31, so that when the fixed sleeve333rotates, it may drive the rotating shaft31to rotate without moving the rotating shaft31axially. It is possible to arrange the first limiting part311on the rotating shaft31, and by arrangement of the retaining ring, the movement of the rotating shaft31in two axial directions (i.e., towards left and right inFIG.3) can be limited. Moreover, it is possible to limit the movement of the rotating shaft31in the two axial directions by providing two limiting parts (the first limiting part311and the second limiting part312). The first limiting part311may be a bearing for preventing axial movement, and the second limiting part312may be an axial sliding stop sleeve, the embodiment of the present application does not limit implementation forms of the first limiting part311and the second limiting part312.

In an exemplary embodiment, as shown inFIG.3, a wire channel313is provided in the rotating shaft31.

Wires or cables or the like are connected through the wire channel313, so that the wires or cables are not affected by the rotation of the instrument.

In an exemplary embodiment, the hydraulic control sub4is provided with three magnetic flux gate sensors (not shown in the figure), and orientations of the three magnetic flux gate sensors are perpendicular to each other.

Among them, orientation of one magnetic flux gate sensor is parallel to a central axis of the electronic sub1, and orientations of the other two magnetic flux gate sensors are perpendicular to the central axis of the electronic sub1. The three magnetic flux gate sensors are horizontally orthogonal in pairs, and according to a corresponding component relationship of geomagnetic field on each sensor, an actual azimuth angle can be obtained by azimuth discrimination and arctangent function operation. Alternatively, the magnetic flux gate sensors may be arranged in other positions below the rotary sub3(as shown inFIG.1, at a side of the rotary sub3close to the hydraulic control sub4), which is not limited in the embodiment of the present application, as long as it can be ensured that the position of the magnetic flux gate sensors relative to the mechanical sub5is fixed, and the angle of the mechanical sub5can be detected.

In an exemplary embodiment, the coring instrument83further includes a balancing sub (not shown in the figures), which is connected with the hydraulic control sub4, and the balancing sub is configured to realize a balance between the hydraulic oil pressure inside the instrument and the mud pressure of the downhole formation.

The balancing sub may be arranged in parallel to the hydraulic control sub4to reduce the effect on the length of the coring instrument83. Alternatively, the balancing sub may be arranged between the hydraulic control sub4and the mechanical sub5. The embodiment of the present application does not limit the arrangement position of the balancing sub.

In an exemplary embodiment, the hydraulic control sub4is further provided with a reverse thrusting arm41, which is configured to separate the coring instrument from a wellhole wall. When the coring instrument83is stuck downhole, action of the reverse thrusting arm41can separate the coring instrument83from the wellhole wall.

In actual operation, when the coring instrument83reaches a target horizon, an azimuth sensor (i.e., a magnetic flux gate sensor) first measures an azimuth of the drill bit (i.e., the mechanical sub5), if the azimuth is not a target azimuth, the two supporting and fixing arms21at the upper part of the coring instrument83are unfolded, the upper part of the instrument is fixed, and then the rotary sub3is rotated to drive the drill bit to swing, the azimuth sensor continues to detect the position of the drill bit while the drill bit is swinging. After reaching the specified azimuth, the rotary sub3stops rotating, an upper thrusting arm42and a lower thrusting arm51are unfolded, the two upper supporting and fixing arms21are retracted to start the coring action. After the coring operation is completed, the upper thrusting arm42and the lower thrusting arm51are retracted. If the instrument is stuck downhole, that is, the instrument is stuck with the wellhole wall at a position where the instrument contacts the wellhole wall for coring, which makes it impossible to separate the instrument from the wellhole wall, the reverse thrusting arm41(installed on a side of the drill bit) is unfolded, such that the instrument can be peeled off from the wellhole wall. In addition, when the instrument is stuck, with a method of controlling the rotary sub3to make the mechanical sub5rotate, the instrument can be separated from the wellhole wall.

The coring instrument83according to the embodiment of the present application can obtain the accurate azimuth of cores drilled downhole, and can drill cores with specified azimuths downhole. In the coring process, the coring instrument83can acquire cores with specified depths and specified azimuths according to the design requirements of geologists, and record, so that the depths of the cores taken downhole and the azimuths of the taken cores can be accurately distinguished on the ground. Geological experts analyze the core, figure out a porosity, a permeability and a saturation of a formation, which together with the azimuth information of the core, may make the analyzed formation data be more accurate, provide more effective information for reservoir evaluation and greatly enhance utilization value of the taken cores.

In the description of the application, it should be noted that the azimuth or position relationships indicated by the terms “upper”, “lower”, “left”, “right” and the like are based on the azimuth or position relationships shown in the drawings, which are only for convenience of describing the embodiments of the application and simplifying the description, rather than indicating or implying that the structure referred has the specific azimuth, or is constructed and operated in the specific azimuth, and thus cannot be interpreted as a limitation on the application.

In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the terms “connect”, “connected with” should be understood in a broad sense, for example, the term “connection” may refer to a fixed connection, a detachable connection or an integrated connection, it may be a direct connection, or an indirect connection through an intermediary, or may be an internal communication between two elements. For those of ordinary skills in the art, the meanings of the above terms in the application can be understood according to actual situations.

The embodiments described herein are exemplary, not restrictive, and for those of ordinary skills in the art that there may be more embodiments and implementation schemes within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of disclosed features are possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element of any other embodiment or may replace any other feature or element of any other embodiment.

The application includes and contemplates combinations of features and elements known to those of ordinary skills in the art. The disclosed embodiments, features and elements of the application may also be combined with any conventional features or elements to form a unique technical solution defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other technical solutions to form another unique technical solution defined by the claims. Therefore, any feature shown and/or discussed in the application may be implemented individually or in any suitable combination. Therefore, the embodiments are not to be limited except those made according to the appended claims and their equivalent substitutions. Various modifications and changes may be made within the protection scope of the appended claims.