Abstract: A breaker composition comprising (i) an acid precursor, (ii) an accelerating agent wherein the accelerating agent comprises a Lewis acid and (iii) an aqueous fluid wherein the effective operating temperature of the breaker composition ranges from about 15° C. to about 120° C. A wellbore servicing system comprising (a) an aqueous-based drilling fluid, wherein the aqueous-based drilling fluid forms water-wet solids in the wellbore; and (b) a breaker composition comprising (i) an acid, (ii) an accelerating agent and (iii) an aqueous fluid. A method of dissolving a filtercake comprising contacting the filtercake with a breaker solution comprising (i) an acid precursor, (ii) an accelerating agent and (iii) an aqueous fluid wherein the filtercake comprises calcium carbonate.

Abstract: A method includes placing a weighted fluid in the subterranean formation. The weighted fluid includes calcium bromide. The weighted fluid includes one or more secondary salts that are each independently an inorganic bromide salt other than calcium bromide. The weighted fluid also includes water. The weighted fluid has a density at standard temperature and pressure of at least about 1.7 g/cm3.

Abstract: A method for milling a wellbore structure comprising: pumping fluid through a mud motor and a milling tool while the milling tool and the mud motor are moved on a string to mill out a wellbore structure; and conveying a diversion agent with the fluid through the string, mud motor and milling tool to introduce the diversion agent to the wellbore, the diversion agent mitigating fluid loss in a low pressure zone.

Abstract: The present invention relates to a hydrocarbon-free emulsion stabilizer, to water-in-oil subterranean treatment fluids comprising said stabilizer and having improved stability and environmental compatibility, and to their use in subterranean treatments.

Abstract: Visco-elastic tyre balancing compositions comprising 1) 85 to 97% by weight of a glycol ether component comprising one or more ethylene/propylene glycol copolymer ethers of the general formula (I) or the general (II) or mixtures thereof R—O{[CH(CH3)CH2—O—]m[CH2—CH2—O—]n}H (I) R1—(O—{[CH(CH3)CH2—O—]m[CH2—CH2—O—]n}H)2 (II) wherein R is hydrogen or an alkyl group of 2-8 carbon atoms; R1 is an alkylene moiety of 2-8 carbon atoms in which the two substituents are not carried on the same carbon atom; m is the mole percentage of propylene glycol in the ethylene/propylene glycol copolymer moiety or moieties; and n is the mole percentage of ethylene glycol in the ethylene/propylene glycol copolymer moiety or moieties, wherein the ratio n:m is in the range from 35:65 to 80:20; each glycol copolymer compound having a number average molecular weight in the range of 2000-10000; and 2) 3 to 15% by weight of a fumed silica gel former; said balancing compositions being visco-elastic and having a Storage Modulus (G?) between

Abstract: A dual circulation fluid hammer drilling system (10) has a fluid hammer (12) which is coupled to a drill string (14). The system (10) utilizes a first fluid (16) and a second fluid (18). The first fluid (16) is delivered through the drill string (14) to drive or otherwise power the fluid hammer (12). The second fluid (18) is also delivered through the drill string (14) but in isolation of the first fluid (16) so they do not mix within the drill string (14). The second fluid (18) passes through a hammer bit (38) of the hammer drill (12) and is directed to flow out from a bit face (20). Thus when the system (10) is in use the second fluid (18) will flow across the bit face (20). The first fluid (16) also exits the drilling system (10) at the hammer drill (12). However the first fluid (16) exits upstream or up-hole of the bit face (20).

Abstract: A ground drill system (10) has a drill string 14 which forms first and second mutually isolated fluid paths (16 and 18) respectively. The drill string (14) has an up hole end (20) coupled to a dual circulation rotation head (22) and a down hole end (24) which is coupled to a drilling tool (12). The drilling tool (12) is operated by the flow of fluid delivered through the first flow path (16). A second fluid outlet (26) is provided intermediate the up hole end (20) and the drilling tool (12). The outlet (26) is in fluid communication with the second fluid flow path (18) and located a constant or fixed distance from the drilling toll (2). The second fluid outlet (26) discharges a flushing fluid flowing through the flushing flow path (18) into a hole being drilled by the drilling system (10). The rotation head (22) provides torque to the drill string (14) and thus the drilling tool (12).

Abstract: A composition and method for use in drilling or completing a subterranean well comprising a solidsfree, high-density brine composed of alkali metal polytungstate and blends thereof. These high-density brines are also useful as wellbore fluids and other non-oilfield fluids requiring high density properties.

Abstract: A method to be used when performing drilling in a well bore and a device for performing the method are disclosed. The method includes positioning in the well bore a drill string comprising at least two pipe conduits, an upper end, and a lower end comprising a drilling tool, thereby forming an outer annulus between the well bore wall and the drill string. A well bore section comprising at least one u-shaped section is drilled. A first fluid with a first density is fed into the outer annulus above the u-shaped section, and a second fluid with a second density is provided within the drill string and around the tool, where the first density is larger than the second density.

Abstract: A method of reducing the viscosity of a water-based drilling fluid without requiring dilution. The method of reducing the viscosity of a water-based drilling fluid, includes: providing a water-based drilling fluid containing a peroxide degradable polymer and a weighting agent, adding a viscosity reducing additive containing an inorganic peroxide to the water-based drilling fluid while maintaining the pH of the water-based drilling fluid at a pH greater than about 8, circulating the water-based drilling fluid having a pH greater than about 8 through a wellbore, and heating the circulating water-based drilling fluid to a temperature of at least about 150° F. so as to activate the inorganic peroxide to degrade the peroxide degradable polymer.

Abstract: An inhibitive water-based polymer mud system and method for using the system in drilling and in stabilizing wellbores for use in water sensitive formations as an alternative to oil-based muds or water-based muds comprising ferro-chrome lignosulfonates. The system comprises a fresh water or salt water base thinned or dispersed with a sulfonated acrylic copolymer having a hybrid/graft lignosulfonate multipolymer structure containing carboxylate and sulfonate functional groups with synthetic polymer side chains covalently linked to a base lignosulfonate material, having a molecular weight in the range of about 1,000 to about 15,000, and having a high anionic charge density.

Abstract: A system and method for monitoring underground drilling in which vibration is monitored by creating a model of the drill string using finite element techniques or finite difference techniques and (i) predicting vibration by inputting real time values of operating parameters into the model, and then adjusting the model to agree with measured vibration data, (ii) predicting the weight on bit and drill string and mud motor speeds at which resonance will occur, as well as when stick-slip will occur, so that the operator can avoid operating regimes that will result in high vibration, (iii) determining vibration and torque levels along the length of the drill string based on the measured vibration and torque at one or more locations, (iv) determining the remaining life of critical components of the drill string based on the history of the vibration to which the components have been subjected, and (v) determining the optimum drilling parameters that will avoid excessive vibration of the drill string.

Abstract: A well drilling system for use with a drilling fluid pump includes a flow control device regulating flow from the pump to a drill string interior; and another flow control device regulating flow through a line in communication with an annulus. Flow is simultaneously permitted through the flow control devices. A method of maintaining a desired bottom hole pressure includes dividing drilling fluid flow between a line in communication with a drill string interior and a line in communication with an annulus; the flow dividing step including permitting flow through a flow control device interconnected between a pump and the drill string interior; and the flow dividing step including permitting flow through another flow control device interconnected between the pump and the annulus, while flow is permitted through the first flow control device.

Abstract: Controlling drilling mud density in drilling operations utilizing concentric drill tubes and at least two different density fluids. The mud required at the wellhead is combined with a base fluid of a different density to produce diluted mud in a riser. By combining the appropriate quantities of drilling mud with base fluid, greater control over the pressure in the wellbore and various risers can be achieved. Concentric drill tubes or risers are disclosed, wherein a first annulus defined within one riser is utilized to carry one fluid to the wellbore injection point, while a second annulus defined within another riser is utilized to carry a combination fluid and cuttings back to the drilling rig. In one embodiment with three concentric drill tubes, a third annulus is also define, wherein the various annuli can be utilized in various combinations to deliver at least two different fluids to the wellbore and return a combination fluid from the wellbore.

Abstract: A method and computer program product of either preventing or minimizing pore pressure increase near the wellbore wall within argillaceous formations through which a borehole has been drilled. By interpreting relevant drilling experience data, the type, extent and time-dependency of wellbore instability mechanisms are determined. The impact of drilling mud designs on the time-dependent wellbore instability and hole enlargement is determined by back-analyzing observed drilling events. At least one field-based criterion relationship between net mud weight reduction percentage ratio and hole enlargement is determined. A maximum allowable percentage ratio(s) of net mud weight reduction and either breakout mud weight or mud weight used for the adopted maximum hole enlargement that the wellbore may experience during drilling is determined. Drilling mud salinity value and salt type to satisfy maximum allowable percentage ratio(s) is then determined.

Abstract: The present invention relates, in general, to subterranean fluids, and more particularly, to subterranean drilling fluids that may be useful for reducing the production of water from a portion of a subterranean formation and/or stabilizing an unconsolidated portion of a subterranean formation while drilling. In some embodiments, the present invention provides methods of reducing the flow of water from a portion of a subterranean formation that comprise contacting the portion of the subterranean formation with an organoaluminum compound, the organoaluminum compound being capable of forming a reaction product in the presence of water. The present invention also includes methods of drilling a well bore in a subterranean formation, methods of enhancing the stability of an unconsolidated portion of a subterranean formation, methods of stabilizing an unconsolidated portion of a subterranean formation, and drilling fluids.

Abstract: A method for reducing circulation loss during drilling operations, the method comprising: performing drilling operations using a water-based drilling fluid system comprising a first amount of water insoluble particulate; providing the drilling fluid system with a second amount of alkali metal silicate, the first amount of water insoluble particulate and the second amount of alkali metal silicate comprising a circulation loss combination; and reducing the pH of the water-based drilling fluid system using a quantity of water soluble activating agent effective to form an effective circulation loss structure after a period of time.

Abstract: A composition and method for use in drilling or completing a subterranean well comprising a solids free, high-density brine composed of alkali metal polytungstate and blends thereof. These high-density brines are also useful as wellbore fluids and other non-oilfield fluids requiring high density properties.

Abstract: The present invention generally provides an inexpensive method for drilling a multilateral wellbore where the pressure exerted on a formation of interest by a column of drilling fluid may be controlled.

Abstract: A process for underbalanced drilling into multiple coal and shale formations, and dewatering the drilled formations, which includes drilling a first borehole through several coal seams to a certain depth; lowering an upstock on the end of a carrier string to the depth of the upper coal seam; lowering a drill string in the carrier string, and angling off of the upstock, to drill a lateral or horizontal borehole within the coal seam; repeating the process for the second coal seam; setting a packer in place above the first coal seam in the annulus between the cased borehole and the carrier string; forming perforations in the wall of the carrier string below the packer; retrieving the upstock from the carrier string; lowering an electrical submersible pump to the bottom of the principal borehole; pumping water from the sump portion to the surface within the annulus of the second drill string.

Abstract: A method and system of drilling straight directional and multilateral wells utilizing hydraulic frictional controlled drilling, by providing concentric casing strings to define a plurality of annuli therebetween; injecting fluid down some of the annuli; returning the fluid up at least one annulus so that the return flow creates adequate hydraulic friction within the return annulus to control the return flow within the well. The hydraulic friction should be minimized on the injection side to require less hydraulic horsepower and be maximized on the return side to create the desired subsurface friction to control the well.

Abstract: Subterranean fluids are provided that have improved environmental characteristics, and more particularly, subterranean fluids are provided that include a hydraulic cement in an invert emulsion. Methods of using such fluids in subterranean operations also are provided. An example of a method is a method of using a fluid in a subterranean formation. An example of a composition is a fluid comprising a hydraulic cement and an invert emulsion of an oleaginous fluid, a nonoleaginous fluid, and an emulsifying surfactant, wherein the emulsifying surfactant: has an LC50 or EC50 that is greater than about 10 milligrams/liter with respect to Skeletonema costatum, Acartia tonsa, Scopthalmus maximus (juvenile), or Corophium volutator; and demonstrates a biodegradability of: greater than about 70% biodegradation in 28 days when tested according to method OECD 301A or 301E; or greater than about 60% biodegradation in 28 days when tested according to method OECD 301B, 301C, 301F, or 306.

Abstract: A system for controlling drilling mud density at a location either at the seabed (or just above the seabed) or alternatively below the seabed of wells in offshore and land-based drilling applications is disclosed. The present invention combines a base fluid of lesser/greater density than the drilling fluid required at the drill bit to drill the well to produce a combination return mud in the riser. By combining the appropriate quantities of drilling mud with a light base fluid, a riser mud density at or near the density of seawater may be achieved to facilitate transporting the return mud to the surface. Alternatively, by injecting the appropriate quantities of heavy base fluid into a light return mud, the column of return mud may be sufficiently weighted to protect the wellhead. At the surface, the combination return mud is passed through a treatment system to cleanse the mud of drill cuttings and to separate the drilling fluid from the base fluid.

Abstract: A method and apparatus for delivering a well treatment fluid to a productive zone of a subterranean formation at the same time that a well bore is being drilled is provided. The method includes the steps of delivering a drill-in fluid to a drill bit drilling a well bore in, or adjacent to, the productive zone; removing drill cuttings from the well bore; and simultaneous with these steps injecting the treatment fluid into the productive zone. The apparatus includes at least three nested tubes, which form one internal flow path and two annuluses. The drill-in fluid and drill cuttings are delivered to, and removed from, the drill bit, respectively, through the internal flow path and one of the two annuluses. The treatment fluid is delivered to the subterranean formation through the remaining annulus and an expandable bladder mounted to the intermediate and outer tubes.

Abstract: A method for controlling drilling mud density at a location either at the seabed (or just above the seabed) or alternatively below the seabed of wells in deep water and ultra deep water applications. The mud recirculation system may be used in conventional drill bit drilling operations or with drilling with casing operations. Drilling mud is combined with a non-gaseous base fluid of lesser density than the mud required at the wellhead to produce a diluted mud in the riser. By combining the appropriate quantities of drilling mud with base fluid, a riser mud density at or near the density of seawater may be achieved. The base fluid may be injected utilizing a wellhead injection device for attachment to the wellhead and for injecting the base fluid into the rising drilling mud at a location below the seabed. The riser charging lines are used to carry the low-density base fluid to the injection device for injection into the drilling mud below the seabed.

Abstract: A system and method for controlling drilling mud density at a location either at the seabed (or just above the seabed) or alternatively below the seabed of wells in deep water and ultra deep water applications. A base fluid of lesser density than the drilling mud required at the wellhead is used to produce a diluted mud in the riser. By combining the appropriate quantities of drilling mud with base fluid, a diluted riser mud density at or near the density of seawater may be achieved. The present invention also includes a wellhead injection device for injecting the base fluid into the rising drilling mud. The riser charging lines are used to carry the low density base fluid to the injection device for injection into the return mud. At the surface, the diluted return mud is passed through a treatment system to cleanse the mud of drill cuttings and to separate the heavier drilling mud from the lighter base fluid.

Abstract: A process for underbalanced drilling into multiple coal and shale formations, and dewatering the drilled formations, which includes drilling a first borehole through several coal seams to a certain depth, defined as a cased borehole; lowering an upstock on the end of a carrier string to the depth of the upper coal seam; lowering a drill string in the carrier string, and angling off of the upstock, to drill a lateral or horizontal borehole within the coal seam; repeating the process for the second coal seam; setting a packer in place above the first coal seam in the annulus between the cased borehole and the carrier string; forming perforations in the wall of the carrier string below the packer; retrieving the upstock from the carrier string; lowering an electrical submersible pump to the bottom of the principal borehole, defined as a sump portion of the borehole; collecting methane gas from the two coal seams through the annulus between the second drill string and the carrier string to the surface; pumping wa

Abstract: Methods of drilling and completing open hole well bores and methods of removing filter cake comprised of a gelling agent and calcium carbonate are provided. A method of the invention for removing filter cake comprised of a gelling agent and calcium carbonate from the walls of an open hole well bore is basically comprised of the steps of contacting the filter cake with a delayed clean-up solution comprised of water and a formate ester and removing the clean-up solution from the well bore.

Abstract: A method and apparatus for controlling drilling mud density at a location either at the seabed (or just above the seabed) or alternatively below the seabed of wells in deep water and ultra deep water applications combines a base fluid of lesser density than the mud required at the wellhead to produce a diluted mud in the riser. By combining the appropriate quantities of drilling mud with base fluid, a riser mud density at or near the density of seawater may be achieved. A wellhead injection device for attachment to the wellhead is used for injecting the base fluid into the rising drilling mud at a location below the seabed. The riser charging lines are used to carry the low density base fluid to the injection device for injection into the drilling mud below the seabed. The cuttings are brought to the surface with the diluted mud and separated in the usual manner. The diluted mud is then passed through a centrifuge system to separate the heavier drilling mud from the lighter base fluid.

Abstract: A method for drilling a well below a body of water as disclosed which includes injecting into the well, at a depth below the water surface, a liquid having a lower density than a density of a drilling mud producing a mixture of drilling mud and low-density liquid in the well. The mixture of drilling mud and low-density liquid is withdrawn from an upper end of the well. The drilling mud and the low-density liquid are separated, with at least a portion of the separated low-density liquid returned to the depth below the water surface and at least a portion of the separated drilling mud returned to an upper end of the drill string.

Abstract: A method and system of drilling straight directional and multilateral wells utilizing hydraulic frictional controlled drilling, by providing concentric casing strings to define a plurality of annuli therebetween; injecting fluid down some of the annuli; returning the fluid up at least one annulus so that the return flow creates adequate hydraulic friction within the return annulus to control the return flow within the well. The hydraulic friction should be minimized on the injection side to require less hydraulic horsepower and be maximized on the return side to create the desired subsurface friction to control the well.

Abstract: The present invention provides an environmental remediation system and method. In one embodiment, the system comprises a nozzle formed from a plurality of tubulars mounted parallel with respect to each other. In one embodiment, a mixing chamber may be provided adjacent the nozzle tip to allow mixing of different fluid just before injection. In another embodiment, different fluids may remain segregated until after injection into the media. The invention may comprise electronic sensors for monitoring the reactions and other physical phenomena. The invention may comprise a control system that may control fluid flow ratios, automatically shut off pumps in response to an operator's command or in response to sensor signals detected. Fluids may be pumped sequentially through one or more tubulars into the media. A packer may be provide to keep fluid within the media. A fluid recovery system may be provided for drawing off and storing excess fluids.

Abstract: A method for circulating drilling fluid in a well system includes drilling a substantially vertical well bore from a surface to a subterranean zone and drilling an articulated well bore from the surface to the subterranean zone. The articulated well bore is horizontally offset from the substantially vertical well bore at the surface and intersects the substantially vertical well bore at a junction proximate the subterranean zone. The method includes drilling a drainage bore from the junction into the subterranean zone and pumping a drilling fluid through the drill string when drilling the drainage bore. The method also includes providing fluid down the substantially vertical well bore through a tubing. A fluid mixture returns up the substantially vertical well bore outside of the tubing. The fluid mixture comprises the drilling fluid after the drilling fluid exits the drill string.

Abstract: A method is disclosed that affords improved stability to wellbores during drilling in argillaceous formations with water-based drilling fluids. The method comprises adding to the drilling fluid a compound of the invention having the capacity in water to generate a highly efficient membrane on argillaceous materials. The compound is soluble in the drilling fluid at least at the pH at which the compound is added to the drilling fluid or exists in the drilling fluid, but is insoluble in the water in the pores of the argillaceous formations, or at least at the pH of the water in such pores.

Abstract: Process for using biodegradable drilling muds, characterized in that a able surface sludge which is stable up to about 100° C., with an adjustable filtrate-reducing power of from 2 to 13 cm3 depending on the amount of filtrate-reducing agent used, and with an electrical stability of greater than or equal to 1000 volts, is introduced into the well at the start of drilling, and in that, when the temperature of the terrain passed through reaches 100° C., the surface sludge is replaced with a bottom sludge which is stable at a temperature above 200° C., the volume of the surface sludge representing from 60 to 80% by volume relative to the total volume of sludge used.

Abstract: The present invention relates to a method and to a fluid for drilling or workover in a well running through a porous permeable formation, wherein a water-based well fluid circulates in said well. In the method, at most 3% by weight of a composition obtained from fat, or an oil, and an alcohol, is added to the fluid in addition to the conventional constituents for such a fluid, the chain lengths of the acid and alcohol parts being chosen such that the ester thus obtained has sufficient dispersion in water, compatibility with said constituents, does not form an emulsion with the reservoir oil and adsorbs sufficiently on the porous formation.

Abstract: A method and apparatus for controlling drilling mud density at or near the seabed of wells in deep water and ultra deep-water applications combines a base fluid of lesser density than the mud required at the wellhead to produce a diluted mud in the riser. By combining the appropriate quantities of drilling mud with base fluid, a riser mud density at or near the density of seawater may be achieved. No additional hardware is required below the surface. The riser charging lines are used to inject the low-density base fluid at or near the BOP stack on the seabed. The cuttings are brought to the surface with the diluted mud and separated in the usual manner. The diluted mud is then passed through a centrifuge system to separate the heavier drilling mud from the lighter base fluid.

Abstract: The invention is a subsea pump that includes pumping elements, each pumping element including a pressure vessel with a first and a second chamber therein and a separating member disposed between the first and second chambers. The first and second chambers are hydraulically connected to receive and discharge a hydraulic fluid and a drilling fluid, respectively. The separating member moves within the pressure vessel in response to a pressure differential between the first and second chambers. A hydraulic power supply is arranged to pump the hydraulic fluid to the first chamber of each of the pumping elements. A valve assembly is hydraulically coupled to the first chambers of the plurality of pumping elements and to the hydraulic power supply. Volume measurement devices are arranged to measure volumes of each of the first chambers and the second chambers.

Abstract: A method and system of drilling straight directional and multilateral wells utilizing hydraulic frictional controlled drilling, by providing concentric casing strings to define a plurality of annuli therebetween; injecting fluid down some of the annuli; returning the fluid up at least one annulus so that the return flow creates adequate hydraulic friction within the return annulus to control the return flow within the well. The hydraulic friction should be minimized on the injection side to require less hydraulic horsepower and be maximized on the return side to create the desired subsurface friction to control the well.

Abstract: The method for releasing the stuck pipe of the present invention uses a combination of components which oxidize the mud cake and generated gas bubbles to create an upward buoyancy for the oxidized mud cake. The spotting method of the present invention comprises adding to the borehole in the region of the stuck pipe: 1) an oxidizer which oxidizes the mud cake; and 2) at least one component which reacts in the borehole to generate a gas. Optionally, but preferably, the spotting method further uses a lubricant which is added to the borehole in the region of the stuck pipe. The lubricant acts to lubricate the oxidized parts of the mud cake. Also disclosed is a spotting fluid system including 1) an oxidizer which oxidizes the mud cake, 2) at least one component which reacts in the borehole to generate a gas, and, optionally a lubricant which acts to lubricate the oxidized parts of the mud cake.

Abstract: A drilling fluid contains caustic, a natural wax, a natural thinner, glycerol, phosphoric acid and/or boric acid, and optionally a gel. The drilling fluid can be prepared in modules. Each module contains additional compounds to improve or change the action of the drilling fluid depending on the condition found in the field. The drilling fluid adjusts the properties of conventional drilling muds including increasing lubrication, thins the drilling mud, decreases bit balling, decreases rock resistance and controls phase separation of the drilling muds.

Abstract: A method and system of drilling multiple radial wells using underbalanced drilling, by first drilling a principal wellbore; then providing a first carrier string having a deflection member on its lowermost end to a certain depth within the principal wellbore; orienting the deflection member into a predetermined direction; lowering a second drill string, such as coiled tubing or segmented drill pipe, down the bore of the carrier string, so that the drill bit on the end of the second string is deflected by the deflection member in the predetermined direction from the principal wellbore and a first multilateral well is drilled. When coiled tubing is used, fluid is pumped downhole through the annulus of the coiled tubing, and into an annular space between the coiled tubing and the carrier string so that it co-mingles with produced hydrocarbons; and the co-mingled fluids and any hydrocarbons are returned to the rig through the annular space between the borehole and the carrier string.

Abstract: A method and system for obtaining core samples using a coring fluid. During the drilling phase of hydrocarbon wells and the like, drilled with existing drilling systems, the bit that drills the well is driven by a string of rotating pipes and drilling mud is introduced in the rotating pipes. The drilling mud rises carrying with it the cuttings produced by the drill bit. Alternatively to the current operating method, the rotating pipes can be removed and a special piece of equipment called a core barrel is mounted thereon. The rotating pipes thus equipped for collection of the "core" are then lowered into the well. According to the present invention, when the rotating pipes are at the bottom of the hole, a sufficient volume of a colloidal, viscous coring or embedding fluid is introduced into the mud circuit to encapsulate a sample of the cuttings, for lifting to the surface and subsequent analysis. The fluid prevents the cuttings from being altered by the drilling mud.

Abstract: The invention concerns wellbore fluids suitable for use in the oil and gas exploration and production industries and embraces fluids used for drilling, completion, workover or packing of wellbores. The invention is especially concerned with biodegradable wellbore fluids the liquid phase of which consists of an oil, or of water-in-oil "invert" emulsions, where the oil phase comprises n-alkanes.

Abstract: A method and system of drilling multiple radial wells using underbalanced drilling, by first drilling a principal wellbore. There would then be provided a first carrier string having a deflection member on its lowermost end to a certain depth within the principal wellbore. There is then lowered a second drill string, such as coiled tubing, down the bore of the carrier string, so that the drill bit on the end of the second string is deflected by the deflection member in a predetermined direction from the principal wellbore. A second fluid is then pumped into an annular space between the coiled tubing and the carrier string to a position that it co-mingles with the first fluid. The co-mingled fluids and any hydrocarbons are then returned upward to the rig through the annular space between the borehole and the carrier string. There is then provided a volume of fluid to establish an equilibrium within the carrier string. The drill bit at the end of the coil tubing is retrieved from the bore hole.

Abstract: A method of drilling a borehole is provided using a drill bit coupled to the lower end of a pair of concentric drill pipes. During drilling a first low viscosity fluid, such as oil or water, is circulated through the pipes while a second fluid, such as a weighted viscosified mud, is kept stationary in the pipe/formation annulus.

Abstract: A percussion drilling tool assembly is provided which operates under fluid pressure to reciproce a hammer, the hammer is disposed in a barrel assembly and operates to strike an anvil bit shank to cause the bit to thereby penetrate a rock substrate material. A central fluid passage through the drill stem of the assembly and through the reciprocating hammer allows a flushing fluid to be used with the drilling assembly to flush cuttings from the hole up and around the drill stem simultaneously with and separate from the fluid operating system for reciprocating the hammer. The drill stem includes intake and exhaust passages for pressured working fluid as well as a mud passage for the flushing fluid or mud, the drill stem is made up in sections connected to form a string which extends the length of the hole and provide the pressured working fluid and mud to the pneumatic tool connected at the end of the drill stem.

Abstract: A method and apparatus for drilling combines the advantages of a high pressure fluid jet with a mechanical drill bit without the high horsepower requirements and associated equipment wear of prior jet drilling systems. A two fluid system is contemplated in which only a small portion of the drilling mud stream is clarified and pumped under high pressure to a number of jet nozzles located on the drill bit face. The high pressure fluid and concentrated drilling mud are conducted separately down the hole by a dual, concentric drill pipe. The power and equipment requirements of such a two fluid system are practical and economic because of the low flow rate and non-abrasiveness of the high pressure fluid when compared to conventional drilling fluids. The high pressure fluid combines with the concentrated drilling mud at the drill bit in order to accomplish the normal purposes of the drilling mud. The returned fluid is processed at the surface separating out solids, mud, and the mud to be clarified.

Abstract: An abrasive-fluid jet apparatus and process for drilling holes in rock having a rotary drill bit with multiple abrasive-fluid jet nozzles in the face of the bit and a stationary drill head housing torque generation apparatus and a rotary mounting holding the rotary drill bit beneath and in rotatable relation to the drill head. Abrasive supply facilities and fluid supply facilities are located at ground level for separate supply of the abrasive and the fluid to the abrasive-fluid jet nozzles. It is preferred that the abrasive be supplied to the nozzles in the form of slurry or foam. The apparatus and process of this invention permits deep hole drilling at lower fluid pressures than and without surface structures required by current deep drilling apparatus and techniques.

Abstract: This invention concerns the production of very deep boreholes. A rotary drilling tool is suspended at one end of a very long line of supporting elements such as a cable. During at least the entire duration of the drilling operation, the borehole is filled at least partly with at least one substance which remains in a liquid state and has a density greater than the mean density of the drilled ground strata. Thus any infiltrations in the borehole and the drilling debris move naturally upwards to the free surface of the liquid substance filling the borehole.