US3498393A - Well control method - Google Patents

Well control method Download PDF

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US3498393A
US3498393A US3498393DA US3498393A US 3498393 A US3498393 A US 3498393A US 3498393D A US3498393D A US 3498393DA US 3498393 A US3498393 A US 3498393A
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gas
drilling
pressure
line
well
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Alfred Gordon West
Chester M Harden
Clyde E Pearce
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W&H PRODUCTION DRILLING Inc
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W&H PRODUCTION DRILLING Inc
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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/06Arrangements for treating drilling fluids outside the borehole
    • E21B21/063Arrangements for treating drilling fluids outside the borehole by separating components
    • E21B21/067Separating gases from drilling fluids
    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/08Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure

Description

March 3, 1970 A, G. WEST ETAL WELL CONTROL METHOD Filed sept. 26, 1967 133 lil l J4 35 J5 i .Z

[Nl/ EN TOR 5 United States Patent O ice 3,498,393 WELL CONTROL METHOD Alfred Gordon West, Chester M. Harden, and Clyde E.

Pearce, Midland, Tex., assignors to W&H Production- Drilling, Inc., Midland, Tex., a corporation of Texas Filed Sept. 26, 1967, Ser. No. 670,559 lint. Cl. EZlb 21/04; E21c 7/08 US. Cl. 175-48 2 Claims ABSTRACT OF THE DISCLOSURE A method is provided for preventing blowouts during drilling of an oil or gas well, which includes circ-ulating a drilling fluid down the borehole, the drilling fluid absorbing gas from the strata being cut by the drill bit. The returning drilling Huid is passed into a separator wherein the gas is separated from the drilling fluid. The ow rate of the gas is continuously measured and from the results of the llow rate measurements the porosity of the formation and bottom hole pressure of the well are indicated. Since it is generally necessary to keep the hydrostatic head somewhat greater than the bottom hole pressure, the hydrostatic head is then adjusted by increasing or decreasing the density of the drilling fluid.

Apparatus is provided for measuring the gas flow rate from the separator which includes a plurality of parallel pipes of differing sizes. Each pipe has a flow rate detector, and suitable valves are included for passing the gas flow into whichever pipe is desired, depending on the flow rate. If the flow rate is great, a large pipe is used; if the flow rate is small, a small pipe is used.

BACKGROUND OF THE INVENTION One of the most critical problems in drilling an oil or gas well into the earth is the tendency to lose pressure equilibrium under certain well conditions, resulting in blowout of the well. A blowout is the wasteful blowing of oil and gas out of the well and the complete loss of control of pressure. In view of the tremendous capital investment necessary to drill a well (drilling costs often run to many hundreds of dollars per day and the drilling has often been proceeding for many days when the greatest risk of blowout occurs) it is seen that a blowout is almost always an enormously expensive thing. In addition to the expense involved, a blowout is one of the most devastating and destructive things that can happen to a` well; wells which have blown out are almost always damaged (damage which may be realized throughout the life of the well), and often must be completely abandoned. Even if the well can be brought under control, a great deal of time is often lost in drilling and special equipment and extra labor (which may not be readily available) are needed to bring the well under control.

A still further hazard of the blowout is that the friction of the equipment at the well head can be sufcient to cause a re in the blowout gas, and of course such a re is not only extremely expensive but very dangerous to the workmen at the rig, and ruinous to the rig equipment.

Blowouts most often occur in formations which contain high pressure gas pockets. In the drilling process a drilling fluid or drilling mud is customarily circulated down the borehole to clean the hole of cuttings and lubricate the drill bit. Blowouts can be prevented by establishing pressure control with this drilling mud. That is, if the pressure of the hydrostatic head of the drilling mud is at all times kept greater than the bottom hole pressure of the well, blowouts may be prevented. And the hydrostatic head of the drilling mud can be varied by varying the density of the mud, as is well known in the drilling 3,498,393 Patented Mar. 3, 1970 art. Further, the normal formation pressure of the strata being penetrated may be determined by standard methods. Consequently, it is the present practice to maintain the hydrostatic head at a level considerably greater by some safety factor than the normal bottom hole pressure.

There are two grave difficulties with the use of this safety factor technique. The first is that it does not compensate for the abnormal conditions which sometimes develop, and consequently is only partially effective in preventing blowouts. Secondly, in using the prior art methods a relatively large differential between hydrostatic head and bottom hole pressure must be maintained, which means that the hydrostatic head is at nearly all times much greater than is really necessary.

Maintenance of the hydrostatic head of the drilling uid at a level above what is necessary is in itself a signicant problem to the driller. For example, it has been shown that a lighter hydrostatic head results in a faster penetration rate. And of course, a faster penetration rate is desirable in drilling of wells because of the savings in time required to drill a Well (and hence the cost of drilling), realized. Further, a higher hydrostatic head will result in injury to certain formations which are low in pressure. That is, if the pressure in the bore hole is signicantly greater than the pressure in an adjacent formation, the formation might be fractured by the drilling fluid in the borehole, thereby permanently injuring the formation and forever damaging its permeability to thereby result in permanent decrease of the productivity of the well. Such fracturing is also undesirable because a great deal of the drilling fluid can be lost into the fractured formation. It has also been that longer bit life is achieved with a lighter hydrostatic head. That is, the bit will not wear out so quickly if the mud weight is decreased. This is extremely important since when the bit does wear out, the drilling must be stopped and a trip must be made to replace the bit. This can often take many hours of valuable downtime on the rig. It also results in a buildup of trip gas during the trip, and this gas further contributes to the blowout problem.

As hazardous and as expensive of a problem as it is, a blowout does not occur instantaneously. Rather, it is something which builds up over a period of time (a time period which may be shorty however, if the formation permeability is great) and then, perhaps, is rather instantaneous in its result. For this reason blowouts can be prevented and continuous pressure control established by the use of the present invention.

SUMMARY OF THE INVENTION The present invention provides a method for maintaining pressure control while drilling a well such as an oil or gas well, to thereby prevent the occurrence of a blowout. The method includes generally pumping a drilling fluid such as drilling mud into a borehole while drilling to establish circulation in such a manner that mud introduced into the borehole at the surface proceeds to the bottom of the borehole and then back to the surface. In this manner, the returning mud contains the gases which are present in the borehole. Upon its return to the surface, the mud is introduced into a separator and these gases are sepa-rated from the mud. The mud may be returned to a mud pit for further use.

The gas from the separator is then passed through appropriate lines wherein instruments are located which measure the volume of gas iiow. In this connection, lines of various sizes may be constructed in parallel so that the gas may be directed through different size lines depending on the amount of gas being produced, for more precise measurement. The measurements are recorded, and a record is kept of the measurements from hour to hour and from day to day.

These flow rate measurements will indicate to the operator whether gas is being depleted (smaller flow rate) or whether additional gas is being encountered (greater flow rate). Thus, the well operator is apprised of any unusual condition in sufficient time to take whatever remedial action is necessary. It is noted that the goal sought to be achieved with the use of this invention is the operation of the drilling method with the least possible hydrostatic head on the drilling fluid.

This hydrostatic head uid may be adjusted when necessary by merely increasing or decreasing the density of the drilling mud. If the gas pressure is increasing, the density of the mud is increased to prevent blowout; if the. gas pressure is decreasing, the density of the mud is decreased in order to effect longer bit life, better penetration rate, and to prevent fracture of vulnerable formations.

Pressure control is thus constantly effected during drilling of the well with the result that the possibility of blowout is minimized and the benefits of lowest possible hydrostatic head are realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE l is a schematic elevational view, partially in section, of a borehole during the drilling process, wherein the method of the present invention is employed; and

FIGURE 2 is a side view of apparatus according to one embodiment of this invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS A schematic illustration of a well drilling operation employing the present invention may be seen in FIG- URE 1.

Here it is seen that a borehole has been drilled into the earth extending from the surface 12 to a point 14 beneath the surface, through a plurality of different geological formations 16, 18, and 22. It will be readily understood that as drilling proceeds the borehole 10 will get deeper and deeper.

The borehole 10 is being drilled in this instance by a rotary drill bit 24 suspended at the end of a string of drill pipe or a drill string 26. The bit 24 is rotated by suitable power means 34 located on the derrick floor 36 at the earths surface. Suitable drill collars 28 may be positioned on the drill string just above the drill bit 24 in order to weight the bit and cause it to more effectively drill the formation.

The borehole wall may be protected by the installation of a casing 30 to any desired level in the borehole. In those regions protected by the casing 30, the problem of fracturing discussed above is overcome.

A drilling fluid which may be water or oil, but is commonly mud (a mixture of clay and water with suitable additives), is circulated during drilling from the surface down the center 32 of the hollow drill string 26, past the drill bit 24 at the bottom 14 of the hole, and thence up the annualar area 33 outside the drill string between the drill string and the casing 30 or borehole wall. As the bit 24 is rotated with the drill string by the power means 34, it cuts away at the adjacent formation 22, forming loose cuttings at the bottom of the hole. As the drilling mud sweeps the bottom of the hole, it carries these cuttings upwardly through the borehole to the earths surface. The drilling mud also cools the bit, and serves to maintain the hole gauge by its continual sweeping action.

But the drilling mud provides another vital function and that is to serve as a balance against the bottom hole pressure to thereby prevent blowout. The hydrostatic head is directly related to the depth of the borehole and the density of the drilling mud, by the following equation:

where p is the hydrostatic head in p.s.i., d is the density of the mud in pounds per gallon, and lz is the depth of the column in feet.

Mud density may be regulated by conventional and well known methods (literature available from National Lead Company, Baroid Division, for example) by the addition of weighting additives to the mud before it is introduced into the borehole, and may be readily determined by suitable measurements well known to those of skill in the art. Therefore, it is a relatively simple matter to calculate the hydrostatic head and to adjust the hydrostatic head to any desired value at all times.

The pressure of the fluid in the pores of a rock formation determines the formation pressure of that particular strata. The various formations 16, 18, 20 and 22 through which the borehole penetrates exist at different formation pressures. Since the normal pressure gradient is known for the particular area of drilling, the normal formation pressure may be calculated simply by multiplying the normal gradient times the depth of the borehole. To balance this formation pressure, the driller adjusts the hydrostatic head by increasing or decreasing the density of the drilling mud as mentioned above. And then to allow for pressure surges and higher than expected pressures, a safety factor is added; that is, the hydrostatic head is maintained at a value considerably greater (for example, 750 p.s.i. greater) than the normal formation pressure. This safety factor is necessary because, as mentioned above, the formation pressure varies even within one formation; further, the drill may suddenly hit a relatively high pressure gas pocket.

There are at least two principal difficulties with the use of these safety factors in present practice, as discussed above. The first and most critical is that they are sometimes not large enough to compensate for the extremely high-pressure gas pockets which are sometimes encountered, especially in certain areas of Texas and Louisiana. If such a gas pocket is encountered and the gas pocket formation is of suicent permeability, a blowout may occur. The second problem with the safety factor practice is that the safety factors used are (for the great majority of situations) overly large, to compensate for problems such as that just described. Use of these large safety factors means of course that the hydrostatic head is maintained at a level significantly above and beyond what is generally needed, resulting in lower bit penetration rate, shorter bit life, consequent increase in cost of drilling the well, and the risk of fracturing a low-pressure formation.

In addition to these difficulties, when it is determined that a high-pressure pocket has been encountered (and a blowout has not occurred), drilling through such pocket under present practice is slowed to a very slow pace, resulting again in increased cost of drilling.

Some formations are known as high-pressure, lowvolume formations. Because of their low porosity, there is no real blowout danger in some of these formations even though the gas exists in the pores of the strata at high-pressure. This is simply because not enough of the high-pressure gas can nd its way into the borehole. These formations are often of no real concern to the driller, as far as the blowout problem is concerned, so in some formations only, the ybottom hole pressure may safely be greater than the hydrostatic head.

As the drilling mud sweeps the bottom of the borehole, as seen in FIGURE l, gas from the formation being cut by the drill bit will enter the borehole 10 and will be returned to the surface up the annulus 33 by the mud. Some relatively small amount of the gas will be dissolved in the mud. In accordance with this invention, when this gascontaining mud reaches the surface it is transported by suitable means such as the pipe 38 to a separator 40 suitable for separating the gas from the mud. Suitable choke means may be included in the line 38 to reduce the pressure of the mud-gas mixture to a level which may be properly handled by the separator. In this connection, it has been found particularly advantageous to use the two-stage system illustrated in FIGURE l, comprising the adjustable choke 84 and the hydraulic choke 86. The twostage pressure drop effected in this manner has been found to be effective in preventing high gas pressures from cutting the equipment.

The separator 40, which may operate at any convenient pressure as for example 125 p.s.i., may be elevated so that the mud may return by gravity through a mud return line 44 to a mud pit 46, for later recirculation into the well.

The gas exits the separator 40 through a gas line 42, and is thence measured to determine the volume of gas released from the separator. Such measurement may be made in any suitable manner, one example being illustrated in FIGURE 2.

A multiple ow line system which has been fonud to be particularly advantageous for the measurement of gas ow under all conditions is shown in FIGURE 2. The primary advantage of this particular system is that it allows accurate and precise flow measurements for gas ow rates ranging from very high to very low. In accordance with this system, several lines of different sizes are connected in parallel, with instruments for measuring flow rate positioned in each line. Since it is dicult to get accurate and precise measurements when there is very little flow through a large line, or when there is large flow through a small line, the ow is directed by the operator through the appropriate line by suitable ow control means, depending on the volume of ow.

In this embodiment, the line 42 from the separator may ybe six inches in diameter. Parallel line 50 may be four inches in diameter and may be secured by an elbow connector 51 to the line 42 at a point spaced from the separator 40. Another parallel line 54, which may be three inches in diameter, may be secured by appropriate elbow connection 55, to the line 50.

Each of the parallel lines is in fluid communication at a point spaced from their connection with each other, with a transverse line 62 which communicates with a flare 64 whereby the waste gas is burned a safe distance from the r1g.

Suitable flow control means such as valves are located at appropriate positions in the lines, as seen in FIGURE 2. Valve 52 is located in line 42 downstream from the connection of line 42 with line 50. Valve 58 is located in line 50, downstream from its connection with line 54. In transverse line 62, suitable valves 68, 70, and 72 are located between line 42 and flare 64, line 42 and line 50, and line 50 and line 54, respectively. A small line 60 for use with very small ow rates may be located transverse to the parallel lines 42, 50, 54 and secured in uid communication between the lines 54 and 42. This line may be for example 3A inch in diameter, and may contain an orifice 66 of any suitable size therein.

A rupture plate 56 which may be adapted for rupture when the pressure reaches a certain level, for example `100 p.s.i., is located in line 54 near its connection with line 50.

Suitable ow measurement means, such as pitot tubes, are located in the various lines. Tube 74 is positioned in line 42 between the separator 40 and the connection with line 50; tube 76 is positioned in line 50 between its connections with the lines 42 and 54, tube 78 in line 54 between its connections with the lines 50 and 60, and tube 80 in the line 60 between its connections with the lines 54 and 42, preferably at the orice 66. Each of these tubes or other flow indicators is suitable for measuring the flow rate of the gas passing through the line wherein it is located, and suitable means are connected with each such tube for continuously recording the data received on a recorder 82. In this manner, a continual record of the flow rate of gas returning from the well may be kept.

The manipulation of the various valves in order to effect flow through any of the desired lines is readily apparent yby reference to FIGURE 2. Thus, when the ow rate is relatively large and ow is desired through the line 42, the valve 52 is opened and the valve 58 is closed. But if the ow through line 50 is desired, then the valve 52 is closed and the valve 58 is opened.

Since the flow rate of the gas released from the separator is, assuming constant permeability directly proportional to the bottom hole pressure in the well, these flow measurements enable the driller to keep a constant, up-to-the-minute account of what is happening, pressurewise, downhole. And -by comparing the flow rate measurements with similar measurements taken earlier, the rate of change in the flow rate may also be determined. These measurements thus allow the driller to determine whether a gas zone is depleting or whether additional gas is being encountered, and thus to predict what is happening downhole at any given moment. The operator knows when the drilling has proceeded into a high-pressure gas pocket. The hydrostatic head is then adjusted when necessary by decreasing or increasing the density of the drilling mud by mixing with the mud the appropriate additives.

It is still necessary, of course, in formations which are not relatively low volume formations, to maintain the hydrostatic head at a level somewhat greater than the bottom hole pressure. It will :be recognized that the dilerential employed will vary somewhat depending on the formations being drilled and other factors, but in many contexts of use, it is found that a pressure dierential of about 200-250` p.s.i. is sufficient. This is considerably less than the differential necessary for safety with conventional drilling processes. And it is the difference between the hydrostatic head levels which may be utilized As an example, if it is determined that a 250 p.s.i. differential is appropriate for use in a given situation, the mud density is continually adjusted so that the hydrostatic head is maintained at a level exceeding the bottom hole pressure by 250 p.s.i. Complete pressure control is thus maintained without danger of blowout.

When a high-pressure gas pocket is struck, the driller will have time using the method of the present invention to increase the mud density suiciently to avoid blowout. This is because there is a delay or lag time between the Ibits striking the gas pocket, and any possible blowout, because formations are not suiciently permeable to cause instantaneous blowout. Of course, this lag time varies greatly depending on the permeability of the formation and the pressure of the gas pocket, and therefore it is greatly desired that fairly immediate corrective action be taken whenever necessary. This of course is one of the great advantages of the present invention.

It is here noted that there are presently methods for determining bottom-hole pressure, such as that known as the drill stem test. But such methods are expensive, dangerous, and cannot be continuously performed during drilling of the well. If it is desired to take such a test during drilling of the well while the process of this invention is being used, then such a spot check will allow the driller to better correlate the data received. For example, if the ow rate is increasing, the driller can tell just exactly how much of the increase is due to an increase in bottom hole pressure and how much is due to increased porosity of the formation. Such proced-ures are not generally necessary however. Since the formation porosity is generally known at least to some degree, the measured flow rate of the gas returning from the well (and the rate of change therein) has been found to give a direct and accurate indication of the bottom hole pressure picture. In other words, although the porosity of the formation does have an efect on the ow rate measurements, such effect can usually be discounted to great extent because of the knowledge the driller will 7 have of the formation being drilled, and the safety factor allowed.

It is seen that the invention has provided a method for well control which provides for complete pressure control at all times with minimum risk of costly and dangerous blowout. Further, the invention provides a method which allows for faster penetration rates and longer bit life, resulting in reduced drilling costs. The method of the present invention also is seen to allow for faster drilling through strata wherein the formation pressure is high, and to provide protection against the fracture of low pressure formations.

It is further seen that the present invention provides apparatus suitable for accurately and precisely measuring the llow rate of gas emanating from the well, regardless of whether the ilow is great or small. The apparatus is desirably portarble so that it may be readily transported from rig to rig.

What is claimed is:

1. A drilling method which enables the driller to maintain drilling with a low hydrostatic head and at the same time prevent blowout while drilling a borehole for an oil or gas well into the earth through gas-containing formations, whereupon gas from said formations enters the borehole, comprising:

passing drilling iluid down into said borehole and circulating said iluid back to the earths surface, whereupon gas in the borehole from the surrounding formations is returned to the earths surface by the drilling fluid, some small amount of said gas dissolving in said drilling fluid, but the greater proportion of said gas returning in the drilling lluid as nondissolved gas;

separating the nondissolved gas from said drilling iluid;

measuring the volume flow rate of said separated gas;

recording said flow rate measurement; repeating said process to obtain additional measurements, and recording said further measurements;

comparing the change in measured ilow rate of said over a selected period of time, to ascertain whether gas is being depleted from a gas zone, or whether additional gas is being encountered;

adjusting the density of said drilling fluid from time to time when necessary to maintain the hydrostatic head at the lowest possible level to provied for maximum penetration rate and maximum bit life, and minimizing the possibilty of fracturing low-pressure formations, while at the same time preventing blowout of the well.

2. A drilling method which enables the driller to maintain drilling with av low hydrostatic head and at the same time prevent blowout while drilling a borehole for an oil or gas well into the earth through gas-containing formations, whereupon gas from said formations enters the borehole, comprising:

passing drilling uid down into said borehole and circulating said fluid back to the earths surface, whereupon gas in the borehole from the surrounding formations is returned to the earths surface by the drilling fluid, some small amount of said gas dissolving in said drilling fluid, but the greater proportion of said gas returning in the drilling iluid as nondissolved gas;

separating the nondissolved gas from said drilling lluid;

measuring the volume llow rate of said separated gas;

maintaining a record of said ilow rate and the rate of change thereof;

comparing the change in measured ilow rate of said gas over a selected period of time, to ascertain Whether gas is being depleted from a gas zone, or whether additional gas is being encountered; adjusting the density of said drilling fluid from time to time when necessary to maintain the hydrostatic head at the lowest possible level to provide for maximum penetration rate and maximum bit life, and minimizing the possibility of fracturing low-pressure formations, while at the same time preventing blow-out of the well.

References Cited UNITED STATES PATENTS 2,341,169 2/1944 Wilson et al. 175-66 X 2,923,15'1 2/1960 Engle et al. 175-206 X ERNEST R. PURSER, Primary Examiner Edward M. Fletcher, Jr.

UNITED STATES PATENT oFEICE CERTIFICATE OF CORRECTION Patent No. 3,498,393 March 3, 1970 Alfred Gordon West et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 32 L after "been" insert shown .Column3, line 75, "p=0.52 dh" shouldread p=0.052 dh Column 4, line 62, after "some" insert such Column 5, line 18, "fonud" should read found Column 6, line 36, after "utilized" insert with the present invention, as compared to those which must be used with prior art methods which is important-rather than the absolute i value of these hydrostatic head levels. These absolute values, of

course, are to a great extent governed by formation properties.

Column 7, line 40, before "over" insert gas Column 8, line l, "provied" should read provide Signed and sealed this 20th day of October 1970.

(SEAL)4 Attest:

WILLIAM E. SCHUYLEE, JR.

Attesting Officer Commissioner of Patents

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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968844A (en) * 1974-09-19 1976-07-13 Continental Oil Company Determining the extent of entry of fluids into a borehole during drilling
US4422513A (en) * 1981-07-06 1983-12-27 Franklin Lindsay J Gas hydrates drilling procedure
US5730233A (en) * 1996-07-22 1998-03-24 Alberta Industrial Technologies Ltd. Method for detecting changes in rate of discharge of fluid from a wellbore
US6105689A (en) * 1998-05-26 2000-08-22 Mcguire Fishing & Rental Tools, Inc. Mud separator monitoring system
FR2798158A1 (en) * 1999-09-07 2001-03-09 Elf Exploration Prod Controlling oil production by injecting fluid into well and diverting returning fluid into oil/gas separator whose liquid level and operating pressure are controlled
US6378628B1 (en) 1998-05-26 2002-04-30 Mcguire Louis L. Monitoring system for drilling operations
US20060105896A1 (en) * 2004-04-29 2006-05-18 Smith George E Controlled centrifuge systems
US20060202122A1 (en) * 2005-03-14 2006-09-14 Gunn Scott E Detecting gas in fluids
US20070084639A1 (en) * 2005-10-18 2007-04-19 Scott Eric L Drilling fluid centrifuge systems
US20090057205A1 (en) * 2007-08-31 2009-03-05 Schulte Jr David Lee Vibratory separators and screens
US20090105059A1 (en) * 2002-11-06 2009-04-23 Khaled El Dorry Controlled centrifuge systems
US20090227477A1 (en) * 2006-10-04 2009-09-10 National Oilwell Varco Reclamation of Components of Wellbore Cuttings Material
US20100181265A1 (en) * 2009-01-20 2010-07-22 Schulte Jr David L Shale shaker with vertical screens
US20100270216A1 (en) * 2008-10-10 2010-10-28 National Oilwell Varco Shale shaker
US20120096947A1 (en) * 2007-04-19 2012-04-26 Fmc Technologies, Inc. Christmas tree with internally positioned flowmeter
US8312995B2 (en) 2002-11-06 2012-11-20 National Oilwell Varco, L.P. Magnetic vibratory screen clamping
US8556083B2 (en) 2008-10-10 2013-10-15 National Oilwell Varco L.P. Shale shakers with selective series/parallel flow path conversion
US8561805B2 (en) 2002-11-06 2013-10-22 National Oilwell Varco, L.P. Automatic vibratory separator
CN103470239A (en) * 2013-08-20 2013-12-25 中国石油集团川庆钻探工程有限公司长庆井下技术作业公司 Pressurized-dragging continuous fracturing process
US9073104B2 (en) 2008-08-14 2015-07-07 National Oilwell Varco, L.P. Drill cuttings treatment systems
US9222319B1 (en) * 2013-06-04 2015-12-29 BlueStone Royalty, LLC LCM recovery tank
US9643111B2 (en) 2013-03-08 2017-05-09 National Oilwell Varco, L.P. Vector maximizing screen

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US2341169A (en) * 1940-12-30 1944-02-08 Nat Lead Co Method and apparatus for detecting gas in well drilling fluids
US2923151A (en) * 1956-12-17 1960-02-02 Phillips Petroleum Co Extracting and analyzing gas from well drilling mud

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Publication number Priority date Publication date Assignee Title
US2341169A (en) * 1940-12-30 1944-02-08 Nat Lead Co Method and apparatus for detecting gas in well drilling fluids
US2923151A (en) * 1956-12-17 1960-02-02 Phillips Petroleum Co Extracting and analyzing gas from well drilling mud

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3968844A (en) * 1974-09-19 1976-07-13 Continental Oil Company Determining the extent of entry of fluids into a borehole during drilling
US4422513A (en) * 1981-07-06 1983-12-27 Franklin Lindsay J Gas hydrates drilling procedure
US5730233A (en) * 1996-07-22 1998-03-24 Alberta Industrial Technologies Ltd. Method for detecting changes in rate of discharge of fluid from a wellbore
US6105689A (en) * 1998-05-26 2000-08-22 Mcguire Fishing & Rental Tools, Inc. Mud separator monitoring system
US6378628B1 (en) 1998-05-26 2002-04-30 Mcguire Louis L. Monitoring system for drilling operations
FR2798158A1 (en) * 1999-09-07 2001-03-09 Elf Exploration Prod Controlling oil production by injecting fluid into well and diverting returning fluid into oil/gas separator whose liquid level and operating pressure are controlled
US8561805B2 (en) 2002-11-06 2013-10-22 National Oilwell Varco, L.P. Automatic vibratory separator
US8312995B2 (en) 2002-11-06 2012-11-20 National Oilwell Varco, L.P. Magnetic vibratory screen clamping
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