US3369619A - Pressure control device - Google Patents

Description

Feb. 20, 1968 R. w. BROWN 3369,619

PRESSURE CONTROL DEVICE Filed April 22, 1965 [BY/7A.. ,L M

United States Patent fce glg Patented Feb. 20, 1968 3,369,619 PRESSURE CONTROL DEVICE Robinson W. Brown, San Antonio, Tex., assignor, by mesne assignments to Bassinger Tool Company, a corporation of Texas Filed Apr. 22, 1965, Ser. No. 449,939 1 Claim. (Cl. 175-317) ABSTRACT OF THE DSCLOSURE A pressure control device for a drill bit. The lower end of the drill bit is closed except for a plur'ality of circulating ports, which direct drilling mud in the vicinity of the teeth, and a central guide opening. Upstream of the circulating ports are a plurality of relief ports which are of greater cross-sectional area than the circulating ports. A v'alve member covers the relief ports when the drill bit is in contact with the bottom of the wellbore. A rod from the valve extends through the guide opening to maintain the valve in such position. When the drill bit is lifted off the 'bottom of the wellbore the Valve member moves downstream uncovering the relief ports so that back pressure of the fiuid in the bore is substantially reduced.

This invention relates to a pressure control device, and particnlarly 'a back pressure control for bits.

During the drilling of Wells, drilling mud or other fluid is commonly circulated downwardly through a drill pipe and ultimately through a drill bit for return flow of the mud or other fiuid upwardly in the annulus of the casing or well bore. `It is customary for the drill bit to have one or more circulating holes of restricted size to obtain a discharge of the mud or other fiuid from the bit with 'a jetting action or at least with sufiicient pressure to agitate and Wash the cutings upwardly from the bit. With jet bits, the pressure drop across the circulating holes may range from about six hundred to about two thousand pounds per square inch, so that the circulating of the drilling mud or fiuid is expensive due to the fuel requirements to develop such pressures and also due to the excessive wear on the pump and engines used for such purpose.

It is therefore an object of the present invention to provide a new and improved device which may be used in conjunction with a drill bit so as to control the pressure drop of the drilling mud or other fluid across the drill bit, whereby an adequate pressure drop is obtained for jeting action when drilling with the bit but 'a reduced pressure drop is obtained when the 'bit is olf bottom.

An important object of this invention is to provide a new and improved device which is simple in construction and reliable in operation for controlling the pressure drop of circulating mud or other fiuid across a drill bit or other tool.

Another important object of this invention is to provide means for stopping the hammer action of a fluid operable percussion drill such Ias that disclosed in my copending application Ser. No. 365,980, and the continuation-in-part thereof, Ser. No. 444,907, filed Mar. 17, 1965.

Still another object of this invention is to provide a new and improved device which is movably mounted in a drill bit for movement from a first position which provides for jetting action of drilling mud or other fiuid to a second position for discharging the drilling mud or fiuid with a reduced b'ack pressure.

A further object of this invention is to provide a new and improved device which is movably mounted in a drill bit for movement from a first position which provides for jetting action of drilling mud or other fiuid when the bit is on bottom of the bore hole to a second position for reducing the back pressure of the dlling mud or other fiuid while the bit is raised off of the bottom of the bore hole.

The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.

The invention will be more readily understood from a reading of the following specification and 'by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:

FIG. 1 is a Vertical view illustrating the present invention with a drill bit located on the bottom of a bore hole; and

FIG. 2 is a view similar to FIG. 1, but illustrating the drill bit in a raised position wherein the back pressure of the fiuid within the bit is reduced.

In the drawings, the letter B designates generally a drill bit or other tool which is mounted on a drill collar or drill string D, a portion of which is illustrated in the drawings. Briefly, the drill bit B is supplied with mud or other drilling fiuid in the usual manner for performing drilling Operations to drill a well bore W. A v'alve V is mounted with the drill bit B or other tool for controlling the back pressure of the fiuid fiowing in the drill collar D and discharging from the drill bit B, as will be more evident hereinafter.

Considering the invention more in detail, the drill bit B has a longitudinal bore 10 which is open -at its upper end 10a and which is closed at its lower end 10h. The upper end 10a is thus open for communication with the longitudinal passage 11 within the drill collar D and the pipe string thereabove.

The closed lower end 10b of the longitudinal central bore 10 is provided with one or more circulating ports 12 which are of conventional construction for discharging drilling mud or other fiuid from the bore 10 to the bottom 14 of the bore hole W being drilled by the bit B. Such circulating holes 12 discharge the mud or fiuid in the vicinity of the drill bit teeth 15, or they may jet the mud or fiuid directly onto the bottom 14, depending upon the particular angle and the location of such ports 12, as iS well known. If the drill bit B were of normal construction, it would have a body 16 without any openings therein other than the circulating ports 12 which communicate with the inner bore 10. In the usual jet bit, which may be of the drag bit type as illustrated in the drawings or of any other suitable construction, the pressure drop across the circulating ports 12 ranges from about six hundred 'pounds per square inch to about two thousand pounds per square inch. Such back pressure within the bore 10 and also in the longitudinal passage 11 of the drill string is thus relatively high so that the circulation of the drilling mud or fiuid requires a substantial amount of fuel at the surface for pumping. Such circulation pressure continues whether the bit B is on the bottom or is off of the bottom in the conventional construction.

However, with the present invention, the body 16 is provided with one or more relief ports or openings 20 which are provided to relieve the back pressure within the bit B and the drill string thereabove when the bit B is off of the bottom 14 of the well hole W. The openings 20 are larger in cross-section than the openings 12 so that the total volume passing through the openings 20 `as compared to the openings 12 is much greater when the openings 20 are exposed to communication with the bore 10.

The valve V includes a valve element or body 30 which has one or more longitudinal passages 30a therethrough. The total cross-sectional area of the passages 30a is preferably substantially the same as the total cross-sectional area of the circulating ports 12.

A valve stem or rod 32 is formed integrally with or is attached to the bottom portion of the valve element 30, preferably at the central area thereof. The rod 32 extends through a guide opening 33 in the bit B and projects outwardly from the bottom of the bit B to engage the bottom 14 of the Well bore W. When the bit B is on the bottom 14 for drilling Operations, the rod 32 is in the position shown in FIG. l, having positioned the valve element 30 in alignmentxwith the inner ends of the relief ports 20 to close off communication between such ports 20 and the longitudinal bore 10. A fiudseal such as an O-ring 35 formed of rubber or other similar material is provided for sealing engagement with the annular` external surface of the valve element 30 when the element 30 is in its raised position closing the ports 20.

It will be understood that when the valve V is in the position shown in FIG. l, the valve element 30 closes only the` ports 20 since the longitudinal passages 30a are open for the fiow of fluid from the drill string downwardly and outwardly through the circulating ports 12 for normal drilling Operations.

The length `of the rod 32 is such that when the bitrB is raised off of the bottom 14 of the well bore W,\the valve element .30 is pumped downwardly and is positioned with its upper end 301) below the inner ends of the relief port 20 as shown in FIG. 2, whereby the drilling mud or fluid is then discharged from the bore through the relief ports 20. The longitudinal passages 30a may be positioned so as to have their lower ends closed by engagement with the vclosed lower end 10b when the valve element 30 is in the lower position,` althoughthis `is not necessary since such passages 30a may be Open for fiow through the eirculating ports 12 even when the valve element 30 is in the lowermost position. In fact, if the openings 30a are so aligned with respect to the ports 12 as to permit the fiow of the drilling mud or fluid through the ports 12 while the mud is also being discharged through the relief ports 20, a greater reduction in the back pressure within the longitudinal bore 10 is accomplished. It should be noted that the position of the valve element 30 illustrated in FIG. 2 is not necessarily the lowermost position since the lower surface 30a may engage the closed lower end 10b to limit the downward movement of the valve element 30 when the drill bit B is raised sufiiciently to completely lift the lower end of the rod 32 from contact with the bottom 14.

In the operation or use of the Controlled device of this invention, the drill bit B is operated in the normal way when it is on the bottom 14 of the well bore or bore hole W for drilling purposes. The drilling mud or fluid is supplied to the drill bit B through the circulating ports 12 with the valve element 30 in the raised position shown in FIGn 1 so as to obtain the necessary pressure drop to produce the jetting action Or other circulation of the cuttings from the drill bit B. i 'i 4 When it is desired to stop the drilling With the btB, or it is desired to simply reduce the back pressure of the fluid within the drill string for any purpose, the drllmg string may be lifted to raise the drill bit B off of the bot-' tom 14 of the well bore W so that the valve element 30 is moved downwardly to open the relief ports 20 as shown in FIG. 2. At that time,the back pressure of the fluid Within the drill string is redueed, the extent of which may be determined by the sizes of the openings or ports 20. In any event, the reduction in the back pressure of the fluid is sufiicient to reduce the pumping energy at the surface of the well, thereby saving fuel costs and undue wear onthe pump and engines at the surface which are provided-for circulating the fluid.

The foregoing disclosure and description of the inventon is 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 within the scope of the appended claim without departing from the spirit of the invention.

What is clairned is: 1. A back pressure device, comprising: (a) a well tool having a longitudinal bore with i a closed lower end, (b) said lower end having port means therethrough for the fiow of fluid from the bore through the port,

(e) said tool also having Outlet means which has a greater crOss-sectional area than said port means so that the back pressure offluid in the bore is reduced` when fluid is fiowing through the Outlet means as eompared tO when fluid is fiowing through the port means only,

(d) said closed lower end having a guide opening therethrough,

(e) a valve element disposed in the longitudinal bore -and` having a rod extending downwardly therefrom` and through the guide Opening,

(f) said rod projecting below the bottom of the well tool when the valve element is in a first position to admit fluid to the Outlet means, and

g) said rodr'being movable upwardly relative to the well tool for moving the valveelement upwardly relative to the Outlet means for'closing same.

References Cited UNITED STATES PATENTS 2,169,223 8/1939 Christian -3l7 2,345,024 3/ 1944 Bannister 175-232 X 1,619,328 3/1927 Benckenstein 175-'-3 17 3,025,919 3/1962 Angel 175-3l7 CHARLES E. O'CONNELL, Primary Examner. NI e- BYERS, JR, Examf'wf,

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