Patent Application
20100258351
1. Technical Field
The present invention relates in general to taking measurements while operating a tool downhole and, in particular, to an improved system method and apparatus for a downhole string of equipment having integrated measurement while operating components.
2. Description of the Related Art
Measurement while drilling (MWD) systems are used for monitoring the path of the wellbore as it is drilled, and for evaluation of the formation that surrounds the wellbore. The MWD tool comprises numerous sensors, electronic controlling boards, a power source, and a transmitter. These components are installed inside a pressure housing and typically centralized in the bore of a conventional non-magnetic drill collar. The drill collar is typically positioned on the top end of the mud motor. The mud motor rotates the drill bit at an offset angle so as to cause a deviation in the wellbore path. The orientation of this offset angle is monitored by the MWD tool, and the collected data is sent to the surface where it is displayed to the drilling crew. The crew uses this data to reorient the drill string as needed to control the wellbore path.
The presence of the MWD tool centralized in the drill collar, however, reduces the mud flow area and interrupts the flow pattern. This flow restriction created by MWD also minimizes the size and concentration of particulate that can be present in the drilling mud. These types of mud components or loss circulation materials (LCM) are used to control and reduce, for example, the loss of mud volume to the formation that is being penetrated and frictional drill string drag. Although known solutions are workable, it would be beneficial to perform measurement during operation without having a reduced flow area or compressed cross-section of the flow area through the downhole tool.
Embodiments of a system, method, and apparatus for a downhole string having integrated measurement while operating components are disclosed. For example, a drilling member may contain measurement while drilling (MWD) components has a unique shape and elements. A chassis has external slots or pockets machined into it from its outer diameter. The size of the longitudinally milled slots in the chassis is determined by the size of the components. The chassis is then inserted and sealed into a modified drill collar from the axial end. The mud flow path is positioned off-center because of the component slots. The geometric shape of the flow path through the tool is shaped to optimize the flow area and maintain a wall thickness that can withstand the mud pressure. The wall thickness surrounding the flow area is driven by the sum of the maximum hydrostatic pressure and the circulation pressure.
The flow path contains no obstructions, thereby allowing the drilling operation to utilize a larger size and higher concentrations of loss circulation materials. The design reduces the number of seals required to only one (or a single set) at each end of the chassis, which enhances the overall system reliability. The MWD components are mounted in the chassis slots before the chassis is inserted into the modified drill collar from one axial end. The flow diverters are held in place on the axial ends of the chassis with other drilling subs. The flow diverters are designed to provide a smooth transition for the mud flow cross-sectional areas, and to control material erosion.
At the upper end of the tool, an isolation connection may be attached as part of a gap sub. The gap sub provides a means for the data signal to be transmitted to surface. The transmission signal comprises an electromagnetic signal that is driven onto the drill string sections that exist on either side of the insulated connection. The orientation of the integrated MWD system with respect to the offset bend of the mud motor must be known. A series of alignment pins may be used to maintain orientation.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the present invention, taken in conjunction with the appended claims and the accompanying drawings.
So that the manner in which the features and advantages of the present invention are attained and can be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the appended drawings. However, the drawings illustrate only some embodiments of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
Referring to
In the illustrated embodiment of
The MWD integrated system 21 comprises a drill collar 23 (
The chassis 31 is mounted in the drill collar 23 through one of the axial end openings 27. The chassis 31 has external pockets 33, 35 formed in an exterior thereof. The external pockets 33, 35 may be machined into the chassis 31 from an outer diameter thereof such that the external pockets 33, 35 comprise longitudinally milled slots. Various MWD components 37, 39 are mounted in at least one of the external pockets 33, 35. The external pockets 33, 35 also may house an internal steering module 39 (e.g., a series of electronics boards and modules) for measurement while drilling. Other sleeves or components may be located between the drill collar 23 and the chassis 31. The MWD components 37, 39 are mounted in the chassis slots or pockets 33, 35 before the chassis 31 is inserted into the modified drill collar 23 from one axial end 27.
The chassis 31 further comprises a mud flow path 41 extending therethrough in an axial direction. In the embodiment of
The MWD integrated system 21 may further comprise flow diverters 45, 47 adjacent the axial ends for providing a smooth transition of mud through the chassis 31 and to control material erosion. The flow diverters 45, 47 may be retained between the chassis 31 and other drilling subs. As best shown in
In some embodiments, a communications device 43 (e.g., gap isolation assembly in
In other embodiments, the method may comprise forming the drill collar with a smooth, cylindrical, uniform exterior surface with no external pockets, and further comprise mounting flow diverters adjacent the axial end openings for providing a smooth transition of mud through the chassis and to control material erosion. Alternatively, the mud flow path may be provided with an axial sectional shape comprising a multi-lobed aperture without obstructions extending therein, a wall thickness of the chassis surrounding the mud flow path is selected to withstand a total pressure load comprised of a sum of a maximum hydrostatic pressure in a well and a circulation pressure in the mud flow path, and the chassis has only one seal adjacent the axial end openings.
In still other embodiments, the method may comprise configuring the MWD components as batteries, sensors and electronics, and the sensors and electronics are located opposite the mud flow path, and batteries are located on each side of the mud flow path adjacent the sensors and electronics. In addition, the gap isolation assembly may comprise an isolation connection and permits a data signal to be transmitted to a surface of a well, the data signal comprising an electromagnetic signal that is driven onto drill string sections on either side of the insulated connection; and further comprising alignment pins to maintain an angular orientation of the chassis with respect to an offset bend of a mud motor.
The invention has numerous advantages. For example, the flow path contains no obstructions, thereby allowing the drilling operation to utilize larger sizes and higher concentrations of loss circulation materials. The unique shape and elements of the design permit the chassis to be axially inserted into the modified drill collar so the electronics do not have to be installed and sealed on the sides of the tool. The sizes of the longitudinally milled slots in the chassis may be selectively determined by the size of the components.
The shape of the mud flow path through the tool optimizes the flow area and maintains a wall thickness that can withstand the mud pressure. The flow diverters provide a smooth transition for the mud flow and control material erosion. The flow path contains no obstructions, thereby allowing the drilling operation to utilize larger sizes and higher concentrations of loss circulation materials. In addition, the invention also reduces the number of required seals to only one at each end of the chassis, which enhances the overall system reliability.
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
