US 3163238 A
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Description (OCR text may contain errors)
Dec. 29, 1964 R. A. MALOTT 3,163,233
UNDERWATER WELL DRILLING METHOD AND APPARATUS Filed Sept. 28, 1962 3 Sheets-Sheet 1 INVENTOR:
R. A. MALOTT BY:% 4 7 eQ JwUQ HIS AGENT R. A. MALOTT Dec. 29, 1964 UNDERWATER WELL DRILLING METHGD AND APPARATUS 3 Sheets-Sheet 2 Filed Sept. 28, 1962 fl ll FIG.
R. A. MALOTT BY: H. 1
HIS AGENT R. A. MALOTT Dec. 29, 1954 UNDERWATER WELL. DRILLING METHOD AND APPARATUS 3 Sheets-Sheet 5 Filed Sept. 28, 1962 FIG. 9
R. A. MAUOTT BY: Q
HIS AGENT 3,163,238 Patented Dec. 29, 1964 United States Patent Ofiice 5,163,238 UNDERWATER WELL DRILLING METHOD AND APPARATUS Raymond A. Maiott, Fullerton, Califi, assignor to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Sept. 28, 1962, Ser. No. 226,938
'10 Claims. (Cl. 175-5) This invention relates to the underwater drilling of oil and gas wells and pertains more particularly to methods and apparatus for maintaining contact with an underwater well While changing a bit during drilling operations or when installing in the well a conductor, foundation pipe, or large-diameter well casing.
During recent years, the continued search for oil has resulted in developing methods and apparatus for drilling underwater wells at locations where the water may range from 100 to l500 feet or more in depth. In these locations it is customary to position the wellhead at a considerable distance below the surface of the water, preferably on the ocean floor, so that it is not a hazard to navigation of ships in the area. 7 One method of drilling and completing Wells underwater in this manner is described in copending patent application, Serial No. 830,538, filed July 30, 1959, and entitled Underwater Well completion Method.
, One of the most important operations in the drilling of an underwater well is that of starting the well and installing the conductor or foundation'pipe'in the ocean floor. This operation may be carried out in any one of several ways/two of which are described in US. Patents 2,929,- 610 which issued March 20, 1960 to H. Stratton, and US. 2,891,770 which issued June 23, 1959 .to R. F. Bauer et al. In one method a drill bit drills a hole in the ocean floor slightly larger in diameter than the diameter of the well conductor or foundation pipe which is subsequently slipped down along the drill pipe and'into the hole during which time drilling fluid is pumped dOWn the drill pipe and up the outside of the foundation pipe. In another method, a hole is flushed in the ocean floor .for the well conductor or foundation pipe by pumping fluid down through the conductor, allowing it to jet out the lower endthereof to wash a hole in the ocean floor into which the conductor pipe is progressively lowered. The conductor pipeis then held in place in the hole until the surrounding earth has had time to settle in aroundtheoutside of the pipe and anchor it firmlyin the hole.
In certain locations, the above-described methods of starting to drill a well in the ocean floor and positioning a well conductor or foundation pipe therein are unsatisfactory because of the soil conditions of the ocean floor. In some areas it is necessary to change the bit prior to installing the well conductor or foundation pipe. In employing one of the presently-known methods of starting a well in the ocean floor it is impossible to change a bit at the end of the drill string since contact would be lost with the hole in the ocean floor'when the drill string and its bit were withdrawn to the vessel at the surface of the ocean in order to change the bit.
It is therefore a primary object of the present invention to provide a method and apparatus for starting the drilling of an underwater well with a drill bit and subsequently.
changing the drill bit'to a new one of the same size or one of another or larger size, withoutlosing contact between the hole in the ocean floor and the vessel on the surface of the ocean.
so that well drilling operations may be continued after the original hole has been drilled or after the foundation pipe has been installed.
These and other objects of this invention will be understood from the following description taken with reference to the drawing, wherein:
FIGURES 1 through 6: are diagrammatic views taken in longitudinal cross section illustrating a floating vessel positioned over a drilling location during the sequential steps of starting a well, removing a core bit, inserting a guide rod in the drill string, suspending the guide rod between the vessel on the surface and-the holein the ocean floor, lowering a foundation pipe along the guide rod into the hole, and withdrawing the running and cementing pipe string fiter cementing operations. 1
' FIGURES 7 through 9 are diagrammaticviews taken in longitudinal cross section illustrating a floating vessel positioned over a drilling location during the sequential steps of starting a well with a core bit, enlarging the hole in the ocean floor with a hole opener bit after withdrawing a guide rod from the drill string, and lowering a foundation pipe along the guide'rod into the hole in the ocean to anchors (not shown). Equipment of this type may be used when carrying on well drilling operations orswell work-over operations in water varying from about 100 feet to 1500 feet or more in depth. The drilling vessclll is equipped with a suitable derrick 16 containing a fall line system which includes a suitable hoist l8, traveling block 19, and a suitable hook and swivel or other connec- V tor means 20 adaptedto be connected to thetop of a drill I tioned on the operating deck, a hingde slip and spider assembly, etc, The derrick 16 is positioned over adrilling slot or well 23 which extends vertically through thebarge in a conventional manner. a When using equipment of the present invention, a slot 23 in the vessel .11 may be either centrally located or extend in from one edge. Alternatively, drilling operations may be carried out over the side of'the vesselwithout the use of a slot. For example, the drilling vessel may be provided with a deck portion which overhangs the hull of the vesselr The drill string 21 preferably includes a.conventional telescoping joint 24 in its length to compensate for the rise and fall of the vessel 11 relative to the drill string 21. The drill string 21 also includes a drill bit 25 at its lower 'end which is provided with anaxial vertical opening'26 (FIGURE 2) therethrough in whichfa pilot or core bit 27 and core barrel 28 may be latched'in a suitable manner well known to the art; As shown in FIGURE 7, the center or auxiliary bit 27a is in the form of aremovabledrag bit having a fluid circulation port 29 on each side thereof. The core barrel 28 (FIGURE 1) and the bit body 28a of the pilot orvcenter bit 27a (FIGURE 7) are providedat the top thereof witha fishing head 30 adapted to be engaged by a conventional. wire-line fishing tool so that the bits 27 and27a may be withdrawn from the main bits 25 and 25a, as desired. In soft formations drilling opera tions may be carried out by using the bit 25 (FIGURE 1) alone without the use of the center bit 27 being positioned 3 in place. One suitable type of drill bit for use with the method of the present invention is a Reed Roller Bit Company BR wire line retractable core cutter and drill bit assembly illustrated on pages 4273-74 of the 1962-63 Composite Catalog of Oil Field Equipment and Services.
In FIGURE 1, after substantially fixedly positioning the drilling vessel. 11 at. the preselected drill location, the drill string 21' is lowered through the rotary table 22 and slot in the barge 23 until it contacts the ocean floor 13. It is assumed that the drill string 21 is provided .With a Kelly or power swivel at its upper end which is rotated in the rotary table 22 so that the entire drill string 21 is rotated to drill the hole 31 in the ocean floor 13.
After drilling the well 31 to the desired depth (FIG- URE 2), a fishing tool 32 and a weight bar 33 are lowered at the end of a wire line 34 to engage the fishing head 30 at the "top of the core barrel 28. At thistime the drill string 21 is stationary. In FIGURE 2the core barrel 28 is illustrated as being retrieved up the drill string to the vessel 11. r
After removing the wire line 34, fishing tool 32, and core barrel 28 from the top of the drillstring 21, an
elongated rod 35 is made up and dropped down the open 7 by threadedly connecting together'several short (say, 30
feet) sections of pipe or rod to make a pipe string or rod string of the length desired. In most instances in practicing the method of the present invention it'is desirable that the elongated rod 35 be of a length slightly greater than the depth of the water in which the drilling operations are taking place. For example, as will be described hereinbelow, in the event that the operating deck of the drilling vessel 11 is 300 feet above the ocean floor 13, it is preferred that the rod 35 be greater than 300 feet long, say 350 feet long, so that the upper end of the rod 35 could be suspended from a drilling vessel 11 (FIGURE 4) while the lower end of the rod remains in the top of the well 31. Thus, it be seen that the 7 rod 35 provides a guide between the vessel 11 and the well 31 along which a drill string, well casing, or other equipment may be guided into alignment with the well 31'.
' approaches the stop member 36, the stop member 36 The upper end of the rod 35 (FIGURE 3) is provided with suitable stop means which may be inthe form of a cross bar 36 or any other suitable formhaving a length at least slightly less than the diameter of the bore 37 of the drill pipe 21 so that it may pass. freely therethrough' as the rod 35 is being dropped down through. the drill pipe or is being withdrawn therefrom, For withdrawing the rod 35 from the drill pipe 21, the upper end of the; rod 35 is provided with a fishing head 38 of a conventional design which is adapted to be engaged by asuitable fishing tool, as illustrated at 32 in FIGURE 2. At the same time the stop member or' bar. 36 is wider than the diameter of the opening 26 in the bit'25 so that the bar 36 could not drop through. It is essential that the cross sectional measurements of the rod 35 be less than that of the opening 26 in the bit 25 so that the rod 35 below the stop member 36 can pass freely downwardly through the opening 26. It is to be understood that a: small-diameter pipe string may be used as well as a rod 35 to act as a guide element between the vessel ll and the well 31 as shown in FIGURE'4. 7
With the rod guide element 35 extending. out the lower end of the drill string 21 as shown in FIGURE 3, if it is desired to change the bit 25 at the lower end of the drill string 21, the rod guide element35 must be of a length greater than the depth of the water, To change'the bit' would seat 'on the shoulder 40 within the lower end of the drill string 21 and the guide rod 35 would be drawn upwardly along with the drill string 21 off the bottom of the well 31. When all the drill string had been returned to the vessel, only the guide rod 35 would extend from the vessel to the well 31. The stopmember 36 at the upper end of the guide rod 35 is removably secured to the top of the rod, as by screw threads, or any other suitable means, so that the stop member 36 can be re- 7 moved allowing the drill bit 25 to be stripped off the top of it and another bit installed in place of it. The. second bit is then lowered with the rod and then along the rod into the hole and drilling operations are continued.
, The well 31 having been drilled to its desired depth in FIGURE 4, a well conductor or foundation pipe. 41 is illustrated as being stripped down over the guide rod 35 after first slidably mounting the lower end of-the tubular member or pipe 41 around the rod 35 below the enlarged upper end thereof. That is, the large-diameter founda-- tion pipe 41, which is slightly smaller in diameter than the hole 31 which was drilled in the ocean floor is made up section by section into a string of pipe of the desired length and lowered downwardly over the guide rod 35. This operation is known as stripping the pipe string 41 over the guide rod 35. One'suitable method for strippingone string ofpipe off or over anotherduring offshore well drilling operations is described in copending patent application, Serial No. 118,989, filed June 22 1961.
If desired, the foundation pipe (FIGURE 5) may be provided with a base plate 42 adapted to be seated on the ocean floor 131 to support the foundation pipe 41 in the hole 31. The lower end of the foundation pipe 41. may also be provided with suitable guide means, such,
the guide rod 35 may slide readily therethrough'; The upper end of the foundation pipe 41 may be lowered; to the ocean floor in any suitable manner well known to the art. For example, a pair of cables (not shown) may be secured to the base plate 42 to lower the foundation pipe from the barge, the cables later serving as guide cables for lowering other equipment to the well. gAlter natively, the upper end of the foundation pipe41' maybe secured in any suitable manner to the lower end-of a running'pipe string 45. This running pipe string may subsequently become the cementing pipe string lwhencement is pumped down it and into the annular space outside the foundation pipe 41' as shown in FIGURE 6. During cementing operations the guide rod 35 would have been withdrawn from the running string 45. It is essential that the stop element 36' (FIGURE 3) be of the retractable type or be small enough so that itcanpass upwardly through the running pipe string 45 (FIGURE 5). After cementing operations have been completed (FIGURE 6) the running pipe string '45 is manipulated to disengage it from the top of the foundation pipe 41. One suitable form of connection well knownto the art is a J-slot connection comprising a pin or lug'46 on the outer surface of the lower end of therunning pipe string 45 with a J-slot 47 grooved in the inner surface of the foundation pipe 41'. V i H In FIGURE 7, another form of apparatusemploying' a slightly different bit 25a illustrates the starting or a well in the ocean floor. After drilling the hole 31am 1 the desired depth, a fishing tool is lowered on a wire line the drill string 21 would be pulled upwardly tothe vessel and disconnected in one or more sections at a time in a conventional manner of withdrawing a drill pipe from a well or up from the ocean floor. As the drill pipe 21 and its bit 25 are drawn upwardly the rod guide member 35 remains stationary with its lower end on the bottom of the well 31 and its stop member 36 stationary as the in an operation similar to that shown in FIGURE 2, to engage the fishing head 30 and pull the center bit 27a back to the vessel 11. A guide rod wouldthen be dropped down through the drill pipe 21a in'oa manner described hereinabove so that it dropped out the opening in the bit 25a as the drill pipe was drawn to the surface.
After changing the bit 25a a new bit 250 would be lowered with the drill string along the guide rod and into the hole after which a new central or auxiliary bit 27a would be lowered through the drill string and latched in place. It is quite apparent that the guide rod 35a (FIGURE 8) would not need to be as deep as the water at the drilling location if the hole opener bit 50 that was subsequently connected into the drill string 21a was to be positioned a considerable distance, say 150 feet, above the lower and smaller drill bit 25a. Thus, when there was still 150 feet of drill pipe 21:: hanging from the vessel 11, the hole opener bit 50 would be connected to the top of that section of drill pipe and then additional sections of drill pipe would be connected above the hole opener bit 50 until the bit 50 was positioned on the ocean floor (FIGURE 8).
As drilling operations continued, the hole opener bit 50 would drill the well 31a to the configuration shown in FIGURE 9. In FIGURE 8 the guide rod 35a is shown as being withdrawn from the drill string 21a by means of wire line 34 while the drill string 21a is suspended within the derrick 16 of the drill barge by means of a suitable pipe clamp 51 and elevator links 52.
After drilling the well to its desired depth, the guide rod 35a would again be dropped down through the drill string, this time being of a length greater than the depth of the water so that the entire drill string could be removed and a string of foundation pipe 41a stripped down over the guide pipe or rod 35a and into the well 31a as shown in FIGURE 9. The cone-shaped guide 43a on the lower end of the foundation pipe 41a prevents the lower end of the foundation pipe 41a from hanging up on the earth surrounding the well as it is being lowered into place. It may be seen that by employing the method and apparatus of the present invention the cumbersome, time-consuming operation of stripping a pipe string over another pipe string in both directions is eliminated since by employing the apparatus of the present invention a guide rod can freely be dropped down through a pipe string to serve as a guide for other tubular members to be moved into the well.
I claim as my invention:
1. A method of drilling an underwater well from a vessel on the surface of a'body of water, said method comprising (a) lowering from the vessel into contact with the formation beneath the body of water a drill string including a bit on the lower end thereof with a vertical opening therein,
(b) forming a hole in said formation with said drill string, a
(c) lowering rod means through said drill string of a size to pass out the lower end thereof and out the opening in the bit with the exception of the upper end of the rod means being of a size to hang up on the lower end of the drill string, and
(d) withdrawing the drill string and bit from the drilled hole and back to the vessel while at least the lower end of the rod means is contained in the hole.
2. The method of claim 1 including the steps of (a) slidably mounting another bit at the upper end of the rod means with the upper end of the rod means passing through an axial opening in said bit,
(b) securing the bit to the lower end of the drill string,
(c) lowering the drill string from the vessel while guiding it along the rod means into the drilled hole in the formation.
3. The method of claim 2 including the steps of (a) lowering a fishing tool through said drill string and engaging the top of the rod means,
(b) withdrawing the rod means to the vessel, and
(c) continuing drilling of the hole in the formation.
4. The method of claim 3 including the step of lowering through the drill string and latching into the axial opening of the bit an auxiliary bit prior to continuing drilling operations.
5. The method of claim 1 including the steps of (a) slidably mounting the lower end of a tubular well member around the rod means below the enlarged upper end thereof, (b) lowering the well member and rod means into the hole in the formation until the rod means engages the bottom of the hole, V
I (c) continuing lowering of the tubular well memberso as to slide it along the rod means until it is at the desired depth in the hole, (d). lowering a fishing tool to engage the upper end of the rod means, and (e) withdrawing the rod meansto the vessel. 6. The method of claim 5 wherein the tubular Well member is lowered by means of a running pipe string secured to the upper end thereof and including the step of subsequently pumping cement through said running pipe string and said well member to cement saidwell member in the hole.
7. Apparatus for drilling an underwater well from a less than that of the opening in the bit so as to fall I .ther'ethrough, the length of the rod means extendible downwardly through the bit being greater than the depth of water in which the Vessel is positioned, and
(f) stop means carried near the upper end of the rod means, said stop means being wider than the vertical opening in the bit.
8. The apparatus of claim 7 including fishing head means carried at the top of said rod means. 4
9. A method of drilling an underwater well from a vessel on the surface of a body of Water, said method comprising (a) lowering from the vessel into contact with the formation beneath the body of water a drill string including a bit on the lower end thereof with a vertical opening therein and an auxiliary bit detachably latched in said opening,
(b) forming a hole in said formation with said drill string,
(c) lowering a fishing tool through said drill string and removing the auxiliary bit, V
(d) lowering rod means through said drill string of a size to pass out the lower end thereof and out the opening in the bit with the exception of 'the upper end of the rod means being of a size to hang up on the lower end of the drill string, and
(e) withdrawing the drill string and bit from the drilled hole and back to the vessel while at least the lower end of the rod means remains in the hole to maintain contact therewith.
10. A method of drilling an underwater well from a vessel on'the surface of a body of water, said method comprising, i
(a) positioning a drilling vessel at a selected offshore location,
(b) lowering from the vessel into contact with the formation beneath the body of water a drill string including a bit on the lower end thereof with a ver- 7 tieal opening therein and an auxiliary bit detachably latched in said opening, (a) forming a hole in said formation with said drill string,
(4) lowering a fishing tool, through said drill string withdrawing the drill string ahd bit from the drilled hole and back to the vessel while at least the lower end of the rod meansremains in the hole. tov maintain contact therewith, and
(g) detaching the drill string and bit from the means at the vessel While detachablysecuring the rod means to the vessel,
References Cited by the Examiner F REI PA E S 9/60 Great Britain.
8/61 Great CHARLES E. OCQNNELL, Primary Examiner. I
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