The present invention relates to the removal of debris from wells drilled in geological formations.
While one of the functions of circulating drilling fluid during the drilling of a well is to prevent drill cuttings from accumulating in the borehole by carrying them to the surface, such circulation may not completely remove all such cuttings (and other debris) from the borehole. Moreover, the conventional circulation of drilling fluid during drilling is particularly inefficient for cleaning out drill cuttings in many high-angle and horizontal wells, sometimes resulting in the formation of a layer of drill cuttings and other solids settling along the low side of the high angle and horizontal drill sections; this is sometimes known as a cuttings bed. The formation of a cuttings bed can cause additional difficulties, for example, by causing increased torque and drag on the drill string.
In the following description of the invention, it is to be understood that although the reference is made to a borehole and/or well bore and the wall of the borehole and/or well bore, it is to be understood that the borehole could be open hole or lined. For example, the terms borehole/well bore have been used to include open holes, cased boreholes and the term borehole wall in that case would actually be the inner surface of an open borehole wall and any casing or other liner lining the well bore.
In one aspect of the invention, there is provided a cuttings bed removal tool for use on a tubular string in a well bore, comprising: a sub having a region of enlarged outer diameter over the string diameters indicated by its upper end connection and an indicator disposed downhole of the region of enlarged outer diameter and having at least one bypass port extending through the indicator to permit passage of fluid in an upward direction through the indicator.
In another aspect of the invention, there is provided a cuttings bed removal system for use in a well bore, comprising: a tubular string including a maximum outer diameter and including a sub having a region of enlarged diameter greater than the maximum outer diameter of the tubular string; and, an indicator disposed about the tubular string downhole of the region of enlarged diameter and having at least one by pass port extending through the indicator.
In another aspect of the invention, there is provided a cuttings bed removal system for use in a well bore, the system including a drill string including a sub having an annular volume restriction region and an indicator disposed about the drill string downhole of the annular volume restriction region and having at least one lateral channel extending therethrough.
In yet another aspect of the invention, there is provided a method of reducing a cuttings bed, comprising: inserting a tubular string from surface into a well bore, thereby defining an annulus between the tubular string and the well bore, the tubular string including inner bore, a sub forming an annular restriction region thereabout, and an indicator disposed downhole of the annular restriction region, the indicator having at least one bypass port extending through the indicator; running the tubular string to a selected depth; and, pumping fluid through the tubular string inner bore and into the wellbore annulus, circulating the fluid in the wellbore annulus from below the indicator, through the indicator bypass ports, and past the sub to surface. The method may further include the steps of retrieving and inspecting the indicator to determine whether sufficient cuttings remain to repeat the steps.
It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Referring to the drawings, several aspects of the present invention are illustrated by way of example, and not by way of limitation, in detail in the figures, wherein:
a is side view of a ported indicator body of an embodiment of the invention.
b is a bottom plan view of the ported indicator body of
a is a side view of an indicator mount of an embodiment of the invention.
b is a cross-section along line I-I of the indicator mount of
a is a side view of a top sub of an embodiment of a tool of the invention.
b is a top plan view of the sub of
The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
A cuttings bed removal tool of the invention may be used to remove waste solids such as cuttings and other debris collected on the low side of a drill section. Such removal may be accomplished by drilling fluid agitation caused by the tool and physical contact of the tool with the waste solids to urge them away from the cuttings bed and out of the borehole.
In operation, drilling fluid may be pumped down through a string into which the tool is installed and into the wellbore. The string may be a work string or a drill string and the fluid may be released into the wellbore through a port in a sub or out through the drill bit. The drilling fluid then passes up the borehole annulus between the string and the wellbore wall. As the drilling fluid passes the tool, an annular volume restriction region on the tool reduces the annular flow area about the tool and causes the annular velocity of the drilling fluid flowing back up the borehole annulus to be increased and, thereby, urges loose the cuttings bed. The tool further includes a ported indicator formed at least in part of a deteriorable material. Remaining debris on the cuttings bed may contact the indicator as the tool is drawn uphole causing the indicator to travel along the cuttings bed; if any such debris does remain, contact with the indicator may result in visible deterioration of the indicator such that viewing the indicator upon removal of the tool may provide the user with some indication of the state of the cuttings bed.
Referring to the embodiment shown in
Tool 100 includes an inner bore 145 extending axially from upper connection 143 and in the illustrated embodiment extending to lower connection 144, the inner bore being positioned to place the tool into communication with the inner bore 103 of the string to which it is attached. As such, fluid, arrows F, pumped through drill string 102 can pass into and through tool 100 via its bore 145. Inner bore 145 in the illustrated embodiment extends through the tool from end to end so that fluid can pass therethrough into the drill bit connected therebelow. It is to be understood that the tool lower end could represent the lower limit of the string and bore 145 could be open at the tool's lower end or the lower end could include ports in communication with bore 145 to allow fluid to pass therethrough into the wellbore 101.
Tool 100 includes an enlarged region 140 on its outer surface that creates an annular volume restriction, indicated at 146, between region 140 and the wellbore wall, compared to the annular volume between the drill string and the wellbore wall, when the tool and string are positioned in the wellbore.
Tool 100 further includes an indicator 106 having at least one port 112 therethrough to allow passage of fluid and cuttings in at least the uphole direction, toward upper connection 143. The indicator may be installed in various ways to act in the annulus about the tool or the drill string adjacent the tool. For example, in the embodiment shown in
Enlarged region 140 of the tool has an outer diameter OD1 less than the inner diameter of borehole 101 in which the tool is intended to be used such that fluid can flow therepast in the annular area around the enlarged region and the borehole. However, OD1 is greater than the average and in some embodiments the maximum outer diameter OD2 of the string with which the tool is intended to be used. As will be appreciated, a drill string generally includes connections sized with consideration as to the outer diameter OD2 of the string. At least upper connection 143 may be sized to correspond to the outer diameter OD2 of the drill string with which the tool is to be used. In particular, the size of upper connection 143 may be selected to correspond and connect to a tubular of diameter less than that diameter OD1 of region 140. In the illustrated embodiment, lower connection 144 also is sized to correspond and connect to a tubular of outer diameter less than that diameter OD1 of region 140. The ends of the tool adjacent to connections 143, 144 may have an outer diameter OD3 that substantially corresponds with that OD2 of the drill string to which the tool is intended to be connected. In such a tool, the ends of the tool have an outer diameter OD3 less than the outer diameter OD1 at region 140.
Region 140 may be formed in various ways, as by forming an area of increased wall thickness on the tool. For example, maximum wall thickness t1 at region 140 may be greater than the maximum wall thickness t2 of the tubulars forming drill string 102 and the maximum wall thickness t3 of the tool ends adjacent connections 143, 144.
The enlarged region of the tool, when placed adjacent to the cuttings bed and in operation, causes an increase in the annular velocity of fluid passing between the region and the borehole wall, which in turn scours the cuttings bed.
Referring to the embodiment shown in
In accordance with the invention, the indicator is provided with at least one passage or port to allow the flow of fluid from downhole upwardly past the outer surface of enlarged region 140 to convey debris from the cuttings bed, and then uphole. The number and size of passages or ports may be selected depending on the diameter and composition of the indicator, the desired flow rate past the indicator and/or the size of the cuttings of the cuttings bed, as would be known by consideration of the drilling and/or borehole parameters. The ports may be sized to permit passage therethrough of the cuttings. The flow rate that is effective to scour the cuttings bed may depend on factors such as the viscosity of the fluid used, the mass of the cuttings, the size of the borehole, etc., which would be understood by one skilled in the art. For example, in some conditions, a flow rate of 2 m3/min to 3 m3/min may be effective for a 13⅜ inch casing. In the embodiment shown in
In various embodiments, the indicator may be secured about the tool or a drill string sub by use of an indicator mount, including at least one port corresponding to and to be aligned with at least one of the indicator ports. Referring to
In operation, contact of the indicator with the cuttings bed may result in visible changes to the surface of the indicator. Referring back to
Another cuttings bed removal tool is shown in
While the illustrated embodiments disclose the engagement of the ported indicator about the subs, it is to be understood that the ported indicator itself may comprise a sub being bracketed between upper and lower subs. Such a ported indicator sub may be provided with connector elements with which it may attach to such upper and lower subs.
Of course, it is to be understood that the cuttings bed removal tool may be formed in other ways. While the embodiments of
In an embodiment of the method of the invention, the tool is made up and run in to the top of the cuttings bed. The borehole may be previously drilled, the drill sting removed and then another string including a tool according to the present invention run into the hole. In some embodiments, the exact location of the cuttings bed may not be positively known, but may be estimated or determined from the angle/trajectory of the well. At the upper end of the cuttings bed, if drilling fluid is not already being circulated through the tool, circulation of drilling fluid is begun and the tool is worked down through the cuttings bed to a desired depth. At a desired depth the tool has passed down through at least a portion of a cuttings bed and disrupted the bed such that at least some of the cuttings have been moved with the circulating fluid uphole of the tool. To most rapidly clear the cuttings bed, the circulation rate should be as high as possible while trying to avoid problematic well conditions, such as, for example, the generation of a back pressure issue. As the drilling fluid continues to be circulated, the tool is then slowly pulled back up towards surface such as to the depth previously believed to be the top of the cuttings bed. The drilling fluid continues to be circulated at this depth until the hole above the tool is substantially clear of drill cuttings. Depending on the length of the cuttings bed, it may be necessary to repeat this procedure over several depths to clean out the borehole in a stepwise fashion; alternatively, the procedure may be repeated several times over the entire length of the cuttings bed to achieve this purpose. In some embodiments, the tool may be pulled to surface while circulating to urge the cuttings along the well. As a check, the tool may be pulled to surface to examine the indicator for damage or wear thereto as would be caused by existence of cuttings bed over which the outer edges of the indicator have passed, which are those cuttings not conveyed with the fluid through the indicator ports and/or those not conveyed past the enlarged region. Of course, it is to be understood that embodiments of the method of the invention are not limited to the apparatus illustrated in these figures.
Another embodiment of the inventive method may include the following, repeated as necessary to achieve the desired reduction of the cuttings bed:
Cuttings carried to surface by the circulating fluid may be disposed (such as into a shale bin) or subjected to whatever processing may be desired.
In addition, some embodiments of the method of the invention may include the further step of retrieving the tool to the surface and visually inspecting it to determine whether the indicator was damaged by cuttings during such retrieval and thus whether enough of a cuttings bed remains to justify repeating the method. In various embodiments, the drill bit may also be used to loosen the accumulated cuttings sufficiently to allow the tool to be brought down to the desired depth.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are know or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”.
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