Abstract: In the presence of certain crude oils, when ferric iron exists in very acidic fluid, it practically instantaneously forms precipitates known as sludges which lead to irreversible damage. Iron control compositions and acid fluids containing such iron control compositions are disclosed. For acid fluids containing up to 15% acid, the iron control composition includes a reducing agent selected from a substituted and unsubstituted thiourea compounds, and a reduction catalyst including a copper (cuprous or cupric) compound. When the acid fluid contains more than 15% acid, for example from 15 to 28% acid, the reducing agent is again selected from substituted or unsubstituted thiourea compounds, and the reduction catalyst is a combination of a copper (cuprous or cupric) compound and iodine (iodine or iodide ions).

Abstract: The invention, in one embodiment, is a novel fracturing fluid composition comprising an aqueous metal hydrated galactomannan gum, buffered to a pH of from about 9 to about 11. In another embodiment, a method of fracturing a formation is disclosed, the method being characterized by the use of the compositions mentioned.

Abstract: The improved recovery of hydrocarbons from subterranean formations by hydraulically fracturing a subterranean formation is accomplished. Fracturing fluids using a viscoelastic surfactant fluid containing wormlike micelles are useful to improve recovery of hydrocarbons and limit the loss of fracturing fluid into the formation fracture face. The invention further relates to novel fracturing methods useful for increasing hydrocarbon production, limiting connate water production, resisting fracturing fluid loss into the subterranean formation, and reducing the equipment requirements in mixing and pumping fracturing fluid. The action of micelles of surfactant in aqueous zones of the subterranean formation facilitates the flowback of increased amounts of hydrocarbons once a fractured well is placed back on production.

Abstract: Wellbore fluids are disclosed which comprise liquid dispersions of particulate mixed divalent metal carbonates having a generally platy crystal form. Mixed alkaline earth metal carbonates are preferred. The invention further relates to a method of well construction, well remediation, or stimulation utilizing such wellbore fluids.

Abstract: A hydraulic wiper plug launcher (8) includes a coupler (22) releasably mounted on the upper end of a well casing (9). The outer coupler body (10) has an inner shoulder (49) and an open ended plug container (12) has a stack of wiper plugs (16) compressed therein. The upper end portion of container (12) forms a fluid chamber (S2) above the uppermost wiper plug (16). A precise predetermined volume of fluid is supplied to fluid chamber (S2) for expelling the plugs (16) in a controlled sequence. The length of the fluid chamber (S2) in container (12) increases an amount equal to the length of the wiper plug (16) pushed or expelled from the open lower end of the container (12).

Abstract: The invention, in one embodiment, relates to a fluid loss control additive or composition comprising a granular starch composition and fine particulate mica, in specified proportions. The invention further comprises a fracturing fluid containing a starch composition and mica, in a specified ratio. In yet a third embodiment, the invention comprises a method of fracturing a subterranean formation penetrated by a borehole, comprising injecting into the borehole and into contact with the formation, at a rate and pressure sufficient to fracture the formation, a fracturing fluid containing starch and mica, in specified ratios, and in an amount sufficient to provide fluid loss control.

Abstract: Apparatus for drilling a well comprising, in one embodiment, a borehole assembly having a motor rotated drill head with ports for emitting a fluid, coiled tubing operatively associated with the drill head to supply fluid and support the drill head, the borehole assembly adapted to drill a channel off axis by varying the speed of the motor drive during a cycle or by varying fluid pressure to the drill head during a cycle.

Abstract: The invention, in one embodiment, relates to a fluid loss control additive or composition comprising a granular starch composition and fine particulate mica, in specified proportions. The invention further comprises a fracturing fluid containing a starch composition and mica, in a specified ratio. In yet a third embodiment, the invention comprises a method of fracturing a subterranean formation penetrated by a borehole, comprising injecting into the borehole and into contact with the formation, at a rate and pressure sufficient to fracture the formation, a fracturing fluid containing starch and mica, in specified ratios, and in an amount sufficient to provide fluid loss control.

Abstract: A wiper plug launching tool includes a body arranged to be lowered into a liner on a running string, the body having a tubular upper portion and a cylindrical lower portion, upper and lower wiper plugs loaded into the lower portion, each of the plugs having upwardly facing elastomer cups that are reduced in diameter during loading, a drive rod movably mounted in the upper portion of the body, a first piston or dart that is pumped down the running string and into engagement with the drive rod so that pressure applied to the first dart forces the rod downward to cause ejection of the lower wiper plug into the liner where cups of the plug expand to provide a moving seal at the lower end of a column of cement, and a second piston or dart that is pumped down into engagement with the first dart to force the rod further downward and cause ejection of the upper wiper plug into the liner where the cups of this plug expand to provide a moving seal at the upper end of the column of cement.

Abstract: A dual injection system for selectively injecting a treating fluid in a predetermined treating zone (16) of a well bore hole (10) adjacent a productive zone (14) with a marker fluid injected from the annulus (36) outside a coiled tubing string (34). The coiled tubing string (34) is inserted within the well bore hole (10) and a sensor (40) is provided on the coiled tubing string (34) with a lower end portion (42) extending below the sensor (40) for the discharge of the treating fluid from the lower end (44) of the extending end portion (42). The sensor (40) senses a detectable material, such as a radioactive material, in the marker fluid injected from the annulus (36) outside the coiled tubing string (34) and may be reciprocated within the well with the coiled tubing string (34) for determining the interface (46) between the marker fluid and the treating fluid so that the treating fluid does not enter the productive zone (18). In one embodiment (FIG.

Abstract: A method is provided for controlling the delay time of aqueous borate-crosslinked polysaccharide-based fluids for hydraulic fracturing and related applications which allows on-the-fly control of the delay time without comprising overall fluid integrity. Without having to modify the total boron content nor pH of the fracturing fluid, the delay time is controlled by adding a polyol to the fracturing fluid at a first rate, determining the resulting delay time and then adjusting the rate of the polyol addition to the fracturing fluid until the desired delay time is achieved.

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: The present invention is directed to an aqueous foamed Drilling Fluid for drilling well bores into a subterranean formation, comprising water, at least one clay and at least one foaming agent. According to the invention, it further comprises at least one metal hydroxide. The invention further relates to a method for preparing said foamed drilling fluid.