GB2164371A

GB2164371A - Well string tubular member

Info

Publication number: GB2164371A
Application number: GB08430008A
Authority: GB
Inventors: Allen Kent Rives
Original assignee: METAL X CORP OF TEXAS
Current assignee: METAL X CORP OF TEXAS
Priority date: 1984-09-13
Filing date: 1984-11-28
Publication date: 1986-03-19
Also published as: BR8405866A; AU3549784A; DE3441995A1; GB8430008D0; NO844545L; NL8403509A; FR2573125A1

Abstract

A well string member such as a drill collar includes an elongated tubular body (M) with an outer circumferential surface (12). First and second groove means (20, 21) each comprising a plurality of grooves (20a, 21a), are provided in the outer surface with the grooves (20a) of the first groove (20) means inclined in one direction and the grooves (21a) of the second groove means (21) inclined in the other whereby the first and second groove means (20, 21) intersect at a plurality of intervals along the surface to form opposed fluid flow paths to assist in positioning the well string in a well bore. <IMAGE>

Description

SPECIFICATION Well string tubular member This invention relates generally to well string tubular members which are adapted to be secured in well strings in a well bore.

Various types of groove arrangements and configurations have been proposed and are in use on well string tubular members. Generally speaking, all configurations provide some form of recesses or grooves on the outer surface of a tubular member for fluid flow between the tubular member and the wall of the well bore. In those tubular members in which spirals are provided in the outer surface, there may be some tendency to increase hole drag due to insufficient fluid flow path in the well bore annulus between the tubular member and well bore wall. This in turn may cause more erosion and wear on the tubular member when it is employed in a rotatable well string such as a drill string.

Further, in drilling some wells, such as thermal wells or high pressure gas wells, the use of heretofore well known and common spirals in a drill collar in a drill string may cause the drill string to tend to spin out of the well bore. Also, when a spiral groove drill collar is employed in a drill string, the resulting manner or direction of circulation of fluid between the drill string and the well bore wall may cause the drill string to move to one side of the well bore, thus creating an auger effect which "walks" or moves the drill string to one side of the well bore during drilling operations.

The present invention provides an opposed spiral arrangement in a well string tubular member and particularly for a drill collar for use in a drill string which provides an opposed fluid flow path in the well string to assist in inhibiting the drill string from spinning out of a thermal well being drilled.

Yet another object of the present invention is to provide a dual spiral arrangement on the outer surface of a drill collar of a drill string to provide a dispersed surface arrangement which maintains surface contact with the well bore wall as may be desired, while enabling less of the drill collar surface to come in contact with the well bore wall during drilling of the well bore.

Still another object of the present invention is to provide a drill collar employing opposed spirals for opposed fluid flow to assist in reducing, if not substantially eliminating walking of the drill string to "auger" or "drill" the well bore off course during use.

Another object of the present invention is to provide a drill collar for a drill string with maximum flow paths while providing circumferential surfaces for stabilizing action in the well bore wall.

A further object of the present invention is to provide a surface configuration on a drill collar, or tubular member, which changes the direction and the velocity of the fluid in the well bore which moves around the collar to thereby aid in centralizing the drill collar in the well bore and also aid in inhibiting differential sticking.

Other objects and advantages of the present invention will become more readily apparent from a consideration of the following drawings and description.

Figure 1 is a side view of the tubular member of the present invention and the preferred arrangement of the opposed groove means in the outer surface of the tubular body; and Figure 2 is a sectional view on the line 2-2 of Figure 1 illustrating further details of the present invention.

Attention is first directed to Figure 1 of the drawings wherein the tubular member of the present invention is referred to generally by the letter M. It includes an elongated tubular body M having threaded means represented by the dotted line 7 at one end and shown in solid line at the other end at 8 respectively of the tubular body M for connecting the body in a well string such as a drill string. The tubular body M has an outer annular surface 12 as illustrated in the drawings. The present invention will be described in relation to a drill collar for use in a drill string as this may be where it has greater commercial application; however, it can be used on any tubular member such as casing and the like.

First groove means 20 are formed in the annular surface 12 of the tubular member or drill collar DC and the first groove means 20 is inclined at an angle in one direction relative to the longitudinal axis of the body M and extends spirally about and over most of the longitudinal extent of the drill collar as shown in the drawings. Second groove means 21 are provided in the annular surface 12 and are inclined in a direction opposite to the angle of inclination of the first groove means 20 as shown in the drawings. The second groove means 21 also extends spirally about and throughout most of the longitudinal extent of the drill collar.

The first groove means 20 and second groove means 21 each are formed by a plurality of grooves circumferentially spaced about and inclined relative to the longitudinal axis of the tubular body M as shown in the drawings. One of the groove means 20a of the first groove means 20 intersects one groove 21a of the second groove means 21 to form a pair P of grooves which intersects between in the annular surface 12, one form of such intersection being more clearly demonstrated in Figure 1 of the drawings as being adjacent the central portion of each first and second groove means 20, 21 and which intersection is represented generally by the letters IM. It can be seen that the pairs of grooves are longitudinally and circumferentially of the tubular body M throughout the portion in which the grooves 20a, 21a are provided.

As shown in Figure 1, the intersection of the first and second groove means 20 and 21 in the outer surface 12 is represented by the vertical line 26 and horizontal line 27 as well as the vertical lines 28 and 29 at the intersection of the ends of the grooves of groove means 20, 21 adjacent, but spaced from each end of tubular member M dem onstrate that the total lengths of intersection of the first and second groove means 20 and 21 on the surface 12 relative to the total length of member M preferably extends over at least approximately 50% of the total length the member M.Thus, substantial intersection of the first and second groove means 20 and 21 is provided in the outer surface 12 of member B to accommodate unrestricted fluid flow in the well bore as it is circulated upwardly around member M from the drilling bit on the lower end of the drill string to the earth's surface in a manner well known in the art.

However, notwithstanding the intersection of the oppositely inclined and intersecting first and second groove means 20, 21 over a relative substantial longitudinal extent of member M, the angle of inclination of the first and second groove means 20, 21 and their angle of inclination is such that surfaces 12a of substantial extent are provided in the ungrooved portion of the annular outer surface 12 of the member M for engagement with the well bore wall during drilling operations to assist in maintaining the drill string positioned in the well bore while accommodating unrestricted fluid flow therearound.

More particularly, with drill collars heretofore used, such as single spiral drill collars, the spiral may, under some circumstances, increase hole drag and may cause more erosion on the drill collar, thus requiring removal of the drill string from the well bore for replacement of the drill collar, which operation is expensive and time consuming.

Further, in some types of well such as thermal wells, the present invention tends to prevent the drill string from spinning out of the hole due to the pressures encountered. The opposed spiral arrangement of the first and second groove means 20, 21 creates an opposed flow of fluid around the drill string and drill collar of the present invention which inhibits any spiraling effect of the drill string with the drill collar of the present invention therein, which spiraling might otherwise be present in the prior art spiral groove drill collars to cause the drill string to tend to spin out of the well bore under pressure. Also, the dual opposed spiral arrangement and intersecting fluid flow path of the present invention assists in inhibiting walking of the drill string to one side of the well bore which may cause the drill string to move off course during drilling operations.

In addition, the circulating fluids in the well bore create a high pressure point of fluid contact in the general region represented by the letter D at the mid-intersection of the first groove means 20 and second groove means 21, and this conjunction of fluid contact changes the velocity and direction of the fluid moving around the drill collar which further tends to assist in centering the drill collar of the present invention in the well bore.

Any suitable number of grooves or milled slots may be employed to form the first groove means 20, and typically two to four milled slots with a right-hand spiral as illustrated by the numeral 20 representing the first groove means relative to the longitudinal axis of the tubular member M may be employed. Similarly, a like number of milled slots forming the second groove means 21 and with a left-hand spiral relative to the longitudinal axis of the tubular member M may be employed as shown.

As noted, one right-hand groove 20 of the first groove means cooperates with one left-hand groove of the second groove means 21 to form a pair P of intersecting first and second groove means as more clearly demonstrated in Figure 1 of the drawings. Similarly, each remaining right-hand spiral groove of the groove means 20 on the outer surface 12 intersects a left-hand groove of the second groove means 21 to form additional pairs P of intersecting first and second groove means on en largement E. Each pair P of intersecting grooves of the first and second groove means 20, 21 is longitudinally and circumferentially adjacent another pair P of first and second intersecting grooves of groove means 20, 21 on the enlargement.

The intersecting arrangement of the pairs of grooves of each the first and second groove means 20, 21 forms a plurality of circumferentially spaced, generally diamond shaped portions 30 in the outer annular surface 12 between the ends of the tubular member M. Such diamond shaped portions 30 are formed between adjacent circumferential pairs P of intersecting first and second groove means 20, 21.

Also, this arrangement of intersecting grooves on the surface 12 forms a plurality of circumferentially spaced, triangular surfaces 35 in the outer annular surface 12 between the ends of each adjacent pair P of first and second groove means 20, 21 adjacent each end of the tubular body M. The surfaces 12a form a plurality of circumferential rows along the longitudinal extent of the member M with the surfaces 12a in one row extending between and longitudinally overlapping the ungrooved surface positions 12a of surface 12 in an adjacent row of the body. The surface portions 12a also are aligned to form longitudinal rows and this configuration provides for excellent fluid flow while providing for multiple surfaces to position the well string in the well bore.

Thus, although the first and second groove means 20, 21 intersect over a substantial portion of the surface 12 of the tubular body M to provide opposed fluid conducting paths which intersect to accomplish the desired results of the invention, the invention also provides an outer surface arrangement by means of the surface 12a so that at least some portion of the outer annular surface 12 will always be positioned to contact the well bore wall to assist in maintaining the drill string properly positioned therein during drilling operations. It will be noted that the ungrooved surface portions 12a on annular surface 12 are dispersed about surface 12.

Also, the surfaces 12a, by reason of the intersecting groove means 20, 21 provide a configuration for surface portions 12a which has substantial annular extent between its ends which decreases in extent towards at least one end, as well as having substantial longitudinal extent for stabilizing effect while maintaining the groove size so as not to interfere with fluid flow.

In prior art spiral groove drill collars, the ungrooved surfaces are of substantially the same size or width throughout their longitudinal extent.

The grooves terminate in spaced relation to the ends of the drill collar for providing tong receiving areas for connecting the drill collar into the well string in a manner well known in the art.

While the angle of inclination of the first and second groove means 20, 21 is shown as being substantially the same and opposed, it can be appreciated that the angle of inclination of the first and second groove means 20, 21 need not be substantially the same so long as the groove means 20, 21 intersect to form surface portions 12a to accomplish the desired results of the present invention.

In use of the present invention, fluid is circulated from the earth's surface down through the bore 40 of the drill collar and discharged through the drill bit at the lower end of the drill string (not shown) in a manner well known in the art. It is then circulated upwardly around the drill string in the annulus of the well bore, that is, between the well bore and the drill string to be communicated to the groove means 20 and 21 in the outer surface 12 of the tubular member M. Since the groove means 20 and 21 are formed in opposite directions on the surface 12 and intersect in the manner as described hereinabove, the fluid flowing in the paths formed by the grooves or milled slots 20, 21 impinges as it circulates through the grooves and discharges from the grooves 20, 21. The direction of fluid flow in the plurality of grooves 20 formed in the surface 12 being in a direction opposite to the fluid flow in the plurality of groove means 21 tends to negate any tendency of the drill string to walk or move from one side or the other in the well bore as may encountered where a plurality of spiraled slots is formed in a drill collar in one direction, such as is common with the prior art.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

Claims

1. A tubular member adapted to be be connected in a well drill string having an elongate body with an outer peripheral surface, first groove means in the peripheral surface inclined in the one direction relative to the longitudinal axis of the body, said second groove means in the peripheral surface inclined in the opposite direction relative to the longitudinal axis of the body, said first and second groove means intersecting in the peripheral surface at a plurality of positions circumferentially and longitudinally spaced along the body.

2. The tubular member of claim 1 wherein said first groove means comprises a plurality of righthand grooves circumferentially spaced on the body and wherein said second groove means comprises a plurality of lef-hand grooves circumferentially spaced on the body.

3. The tubular member of claim 1 wherein the first and second groove means terminate in longitudinal spaced relation to each end of the body.

4. The tubular member of claim 1 wherein the intersecting first and second groove means define ungrooved surface portions in the peripheral surface of the body which are circumferentially spaced about the body.

5. The tubular member of claim 4 wherein the circumferentially spaced ungrooved surface portions form circumferential rows in the peripheral surface of the body with the ungrooved surface portions in one circumferential row extending between and longitudinally overlapping the ungrooved surface portions in an adjacent row of the body.

6. The invention of claim 2 wherein said first and second groove means is arranged on the peripheral surface of the body so that each righthand groove of the first groove means intersects a left-hand groove of the second groove means to form adjacent pairs of intersecting grooves longitudinally and circumferentially of the tubular body.

7. The invention of claim 6 wherein the adjacent pairs of intersecting grooves form an ungrooved surface portion of generally diamond shape on the peripheral surface of the body between each adjacent pair of intersecting grooves.

8. The invention of claim 6 wherein the adjacent circumferential pairs of intersecting grooves form an ungrooved surface portion which is of smaller circumferential extent adjacent the ends thereof than it is intermediate its ends.

9. The invention of claim 8 wherein the ungrooved surface portion is a quadrilateral.

10. The invention of claim 1 wherein the first and second groove means each has a width, depth and angle of inclination relative to the longitudinal axis of said body such that the total extent of intersection of the first and second groove means comprises at least approximately 50% of the total length of the ungrooved peripheral surface in which the first and second groove means are formed.

11. The invention of claim 4 wherein the ungrooved surface portions in the peripheral surface are aligned generally longitudinally of the body and are aligned generally on a plane transverse to the longitudinal axis of the body.