Patent Application
20240376789
The present disclosure relates generally to drilling wellbores and, more particularly, to preventing drill pipe from becoming differentially stuck during wellbore drilling activities.
A significant issue in drilling a wellbore in the oil and gas industry (or other industries) is differential sticking. Differential sticking occurs when the drilling assembly is prevented from rotating or reciprocating within a wellbore. This may occur due to the formation of a thick layer of drilling fluid filter cake (alternately referred to as “mud cake”) on the inner walls of the wellbore. The flush surface of standard drill pipe provides a large contact area for sticking into the mud cake, and may enable a sticking force to be assumed by the drilling assembly (also referred to as “stuck pipe”).
In certain applications, the drilling assembly cannot overcome the force generated from the wellbore differential pressure that pushes the drilling assembly into the mud cake. Standard procedures for freeing a drilling assembly experiencing differential sticking involve using an oil-based mud as a spotting fluid, using mechanical jarring to apply a shock force, adjusting the wellbore's hydrostatic pressure, or any combination thereof. However, these corrective measures for freeing stuck pipe may be costly and introduce further downtime. Further, jarring assemblies and additional corrective measures can include complex internal mechanisms which may fail during operation.
Accordingly, a system for preventing the differential sticking of drill pipe is desirable to prevent downtime and costly corrective measure.
Various details of the present disclosure are hereinafter summarized to provide a basic understanding. This summary is not an exhaustive overview of the disclosure and is neither intended to identify certain elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of this summary is to present some concepts of the disclosure in a simplified form prior to the more detailed description that is presented hereinafter.
According to an embodiment consistent with the present disclosure, a drilling system includes a drilling rig, and a drill string extended from the drilling rig and into a wellbore and including a plurality of sections of drill pipe connected end to end and a drill bit arranged at a distal end of the drill string. At least one section of the drill pipe includes an outer surface and a plurality of raised features extending radially outward from the outer surface.
In another embodiment, a method of drilling a wellbore includes extending a drill string from a drilling rig into a wellbore, the drill string including a plurality of sections of drill pipe connected end to end and a drill bit arranged at a distal end of the drill string drilling rig, rotating the drill bit and thereby extending a length of the wellbore, generating a mud filter cake on an inner wall of the wellbore, preventing differential sticking of the drill string in the mud filter cake with a plurality of raised features provided on an outer surface of at least one section of drill pipe.
Any combinations of the various embodiments and implementations disclosed herein can be used in a further embodiment, consistent with the disclosure. These and other aspects and features can be appreciated from the following description of certain embodiments presented herein in accordance with the disclosure and the accompanying drawings and claims.
Embodiments of the present disclosure will now be described in detail with reference to the accompanying Figures. Like elements in the various figures may be denoted by like reference numerals for consistency. Further, in the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to one of ordinary skill in the art that the embodiments disclosed herein may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. Additionally, it will be apparent to one of ordinary skill in the art that the scale of the elements presented in the accompanying Figures may vary without departing from the scope of the present disclosure.
Embodiments in accordance with the present disclosure generally relate to drilling wellbores and, more particularly, to preventing differentially stuck drill pipe during wellbore drilling activities. The embodiments described herein describe a drill pipe modified with a plurality of raised features and forming part of a bottom hole assembly. The raised features included on the modified drill pipe may prove advantageous in reducing surface contact area with mud filter cake during drilling operations. Through a reduction of surface contact area, the raised features of the modified drill pipe may reduce the sticking force applied to the drill pipe during drilling. Accordingly, the reduced sticking force may be more easily overcome through motion of the drill pipe without a need for jarring, spotting, or repressurization, thus reducing instances of differentially stuck pipe and corrective measures during drill operations.
The BHA 104 includes a drill bit 112 operatively coupled to a tool string 114 which is moved axially within a drilled wellbore 116 as attached to the drill string 106. The depth (length) of the wellbore 116 is extended by rotating the drill bit 112, which grinds and cuts through the underlying rock and subterranean formations of the earth 102. During drilling operations, a drilling fluid or “mud” from a mud tank 118 may be pumped into the drill string 106 and conveyed downhole to the drill bit 112. Upon reaching the drill bit 112, the drilling fluid is discharged through various nozzles included in the drill bit 112 to cool and lubricate the drill bit 112. The drilling fluid then circulates back to the surface 110 via the annulus defined between the wellbore 116 and the drill string 106, and in the process returns drill cuttings and debris to the surface. The cuttings and drilling fluid mixture are processed and returned to the mud tank 118 to be subsequently conveyed downhole once again.
During drilling, the drilling fluid is be forced against the interior wall of the wellbore 116, and at least some portion of the liquid within the mud may permeate into the surrounding earth 102. Following the loss of liquid from the drilling fluid, the remaining drilling fluid components may remain adhered to the interior wall of the wellbore 116 and may form what is commonly referred to as mud filter cake 120. The mud filter cake 120, or “mud cake”, may collect and thicken due to numerous factors, such as poor processing of the drilling fluid through to the mud tank 118. The thickened mud cake 120 may cause sticking of one or more downhole pipes or components, such as the drill string 106 or the tool string 114. The differential sticking of these downhole pipes or components within the mud cake 120 may lead to downtime and expensive corrective measures, such as side-tracking operations or jarring tool deployment.
A layer of mud cake 120 is formed on or against the inner walls of the wellbore 116, and the outer surface 202 of the drill pipe 200 is seated (forced) against the mud cake 120 and may be “differentially stuck,” such that rotation or translation of the drill pipe 200 is substantially or entirely restricted. The differential sticking of the drill pipe 200 may be caused by an imbalance between the surrounding formation pressure 204, which is exerted from within the earth 102 into the wellbore 116, and the fluid column pressure 206 of drilling fluid present within the wellbore 116. With increased fluid column pressure 206, the drill pipe 200 may be pushed against the inner wall of the wellbore 116, as shown, such that the drill pipe 200 enters into and becomes at least partially embedded within the mud cake 120.
The smooth outer surface 202 of the drill pipe 200 may be retained within the mud cake 120 by a differential sticking force 208, or Fs, such that the differential sticking force 208 must be overcome for continued movement of the drill pipe 200. The differential sticking force 208 may be calculated using:
where ƒ is the coefficient of friction of the mud cake 120, A is the surface contact area of the smooth outer surface 202 of the drill pipe 200, and ΔP is the difference between the formation pressure 204 and the fluid column pressure 206. The coefficient of friction of the mud cake 120 may rely on material or fluid properties of the mud (drilling fluid) utilized during drilling, the pressure difference may rely on the characteristics of the formation. In the illustrated example, the smooth outer surface 202 of the drill pipe 200 may provide a large, uninterrupted (continuous) area for contact with the mud cake 120, which may in turn increase the differential sticking force 208. With an increased differential sticking force 208. jarring or further rotation of the drill pipe 200 may become more difficult, and any unsticking process may become more costly and time-consuming.
As the drill pipe 200 enters the mud cake 120, a portion of the smooth outer surface 202 of the drill pipe 200 may become stuck within the mud cake 120. As previously discussed, the magnitude of the differential sticking force 208 may depend partially on the surface contact area exposed to the mud cake 120. As illustrated, an arc length 212 of the outer surface 202 may be in contact with the mud cake 120, and the surface contact area may depend upon the magnitude of the arc length 212 and the length of the drill pipe 200 embedded within the mud cake 120. As will be appreciated, the smooth feature of the outer surface 202 enables a greater surface area to be in contact with the mud cake 120, and thus may generate higher values of differential sticking force 208, which may require corrective measures.
The differential sticking force 208 of the drill pipe 300 in the wellbore 116 will depend on the coefficient of friction of the mud cake 120, the pressure differential between the formation pressure 204 and the fluid column pressure 206, and the surface contact area of the drill pipe 300 in contact with the mud cake 120. While the coefficient of friction of the mud cake 120 and the pressure differential depend upon the specific operation and characteristics of the formation and thus are difficult to alter, according to embodiments of the present disclosure, the surface contact area of the drill pipe 300 may be tuned or otherwise optimized to reduce the magnitude of the differential sticking force 208.
More specifically, as illustrated, the drill pipe 300 provides and otherwise defines an outer surface 302, and a plurality of raised features 304 are provided along at least a portion of the length of the drill pipe 300. The raised features 304 extend radially outward from the outer surface 302 of the drill pipe 300 and thereby provide discrete contact points for the drill pipe 300 against the mud cake 120. In contrast to the larger contact area of the outer surface 302, which is now offset and isolated from the mud cake 120, the raised features 304 may prove advantageous in effectively reducing the magnitude of the differential sticking force 208.
The raised features 304 may be provided on any portion of the drill pipe 300 that may be at risk of differential sticking. In some embodiments, for example, the raised features 304 may be provided along the entire or substantially the entire length of the drill pipe 300, but could alternatively be provided only at select locations along the drill pipe 300 with large gaps of length between raised features 304, without departing from the scope of the disclosure. Moreover, in one or more embodiments, the raised features 304 may extend about the entire outer circumference of the drill pipe 300.
In some embodiments, the drill pipe 300 may include one or more sets 306 of raised features 304. In such embodiments, the sets 306 may be axially aligned along the length of the drill pipe 300, thereby forming axially-offset rows of the raised features 304. More specifically, each set 306 may provide an aligned row of raised features 304 axially offset from an adjacent (uphole or downhole) aligned row of raised features 304. Thus, the raised features 304 may be provided on the drill pipe 300 in a uniform pattern of rows and columns surrounding the drill pipe 300. However, additional patterns or designs may be utilized on the drill pipe 300, without departing from the scope of this disclosure.
In other embodiments, for example, some or all of the raised features 304 may be provided on the outer surface 302 of the drill pipe 300 in a generally helical pattern, as shown in the lower portions of the drill pipe 300 in
With the smaller differential sticking forces 208 of the drill pipe 300, standard drilling operations (movement) may be sufficient to free the drill pipe 300 from the mud cake 120 without the need for corrective measures. The raised features 304 may be applied or installed in any location that may be prone to differential sticking without significant additional costs or system modifications. Further, the drill pipe 300 may not require any internal mechanisms or sensitive components, such that the drill pipe 300 may provide functional reliability which may be lacking in standard operating equipment for prevention and correction of differentially stuck pipe. The prevention of differentially stuck pipe and reduction in differential sticking forces 208 of the drill pipe 300 for cases requiring corrective actions may reduce downtime of operational equipment and costs associated with freeing stuck pipe.
In some embodiments, one or more first raised features 304a may form an integral extension of the drill pipe 300 extending radially outward from the outer surface 302. In such embodiments, the first raised features 304a may be defined by being milled into the outer surface 302 of the drill pipe 300 and, therefore, may be made of the same material as the drill pipe 300.
In some embodiments, one or more second raised features 304b may be secured to the outer surface 302 of the drill pipe 300 using an attachment substrate 402. Examples of the attachment substrate 402 include, but are not limited to, welding, brazing, an adhesive, a magnetic interconnection, or any combination thereof.
In some embodiments, one or more third raised features 304c may be secured to the outer surface 302 of the drill pipe 300 using a mechanical attachment 404 (shown in dashed lines) that mechanically fastens the raised feature 304c to the drill pipe 300. Examples of the mechanical attachment 404 include, but are not limited to, a mechanical fastener (e.g., a bolt, a screw, etc.), an interference fit, a bayonet connection, any combination thereof, or any other force-resistant securing means.
In one or more embodiments, all of the raised features 304a0e included on the drill pipe 300 may be provided in a uniform size and shape, but could alternatively vary in shape and size. In some embodiments, as illustrated, the first, second, and third raised features 304a-c exhibit a generally arcuate, curved, or hemispherical shape that protrudes radially outward from the outer surface 302 of the drill pipe 300. In at least one embodiment, the first, second, and third raised features 304a-c protrude from the drill pipe 300 about 0.5 inches to about one inch. The specific cross-sectional shape of the raised features 304a-c, however, may be chosen based upon the limited surface area of sphere-dependent geometry, as well as for smoother dispersion of stress through the curved surface. In embodiments with a hemispherical shape, the raised features 304a-c may exhibit a diameter 406 of about one inch, while the diameter of the drill pipe 300 may be about 5.5 inches. In such embodiments, the differential sticking force 208 (
In other embodiments, one or more of the raised features 304a-e may exhibit other non-curved cross-sectional geometries, such as conical or polygonal shapes. In such embodiments, one or more fourth raised features 304d may exhibit a pyramidal or conical cross-sectional shape. Moreover, one or more fifth raised features 304e may exhibit a trapezoidal or frustoconical cross-sectional shape. In such embodiments, the fourth and fifth raised features 304d,f may provide one or more points or edges that protrude away from the outer surface 302 of the drill pipe 300. In such embodiments, the non-curved geometry may equally help reduce the surface contact area in contact with the mud cake 120.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, for example, 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 “contains”, “containing”, “includes”, “including,” “comprises”, and/or “comprising,” and variations thereof, 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.
Terms of orientation used herein are merely for purposes of convention and referencing and are not to be construed as limiting. However, it is recognized these terms could be used with reference to an operator or user. Accordingly, no limitations are implied or to be inferred. In addition, the use of ordinal numbers (e.g., first, second, third, etc.) is for distinction and not counting. For example, the use of “third” does not imply there must be a corresponding “first” or “second.” Also, if used herein, the terms “coupled” or “coupled to” or “connected” or “connected to” or “attached” or “attached to” may indicate establishing either a direct or indirect connection, and is not limited to either unless expressly referenced as such.
While the disclosure has described several exemplary embodiments, it will be understood by those skilled in the art that various changes can be made, and equivalents can be substituted for elements thereof, without departing from the spirit and scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation, or material to embodiments of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, or to the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.
