A method of drilling a wellbore includes pumping an oleaginous wellbore fluid into a wellbore, the oleaginous wellbore fluid including an oleaginous continuous phase; a non-oleaginous discontinuous phase; an emulsifier stabilizing the non-oleaginous discontinuous phase in the oleaginous continuous phase; an organophilic clay; a weighting agent; and a wetting agent having an HLB ranging from about 4 to 10.5 that it selected such that the oleaginous wellbore fluid has a 600 rpm dial value at 40° F. of less than about 300 and a 10 minute gel strength of less than about 40 lbf/100 ft.sup.2.

Various embodiments provide methods and systems for providing fluid lighteners for use in downhole wells. The fluid lighteners may include one or more viscosifiers, one or more aphron generators, and a location-specific non-emulsifying surfactant.

An additive composition includes a rheology modifier selected from alcohol ethoxylates, amine ethoxylates, or ethylene oxide/propylene oxide copolymers, wherein the rheology modifier has an HLB ranging from about 4 to 10; and a winterizing agent that is at least one aliphatic non-ionic surfactant that has a branched structure and/or includes at least one unsaturation, wherein the winterizing agent has an HLB value between about 8 and 10.5.

An additive composition for improving one or more cold temperature properties in oil-based fluids is provided. One additive composition may include a first additive component selected from at least one alcohol ethoxylate, at least one amine ethoxylate, at least one ethylene oxide/propylene oxide copolymer, or a combination thereof, wherein the first additive component has an HLB ranging from about 4 to about 10. The additive composition may also include a second additive component selected from at least one alcohol, propylene glycol, at least one alcohol ethoxylate, or a combination thereof, wherein the second additive component has a total number of carbons from about 2 to about 30 carbons and a degree of ethoxylation is from zero to about 10.

Various embodiments provide methods and systems for providing fluid lighteners for use in downhole wells. The fluid lighteners may include one or more viscosifiers, one or more aphron generators, and a location-specific non-emulsifying surfactant.

The invention provides well control system for a riser. The well control system comprises a riser assembly and at least one flow meter. The at least one flow meter is configured to be mounted on the riser.

The present invention relates to a riser system in the form of a pumped riser (1), i.e. a riser (1) having an outlet (6) from the riser (1) at a depth below the surface (S) of a body of water, where the outlet (6) is coupled to a return pump (7) to return fluid from the riser (1) to the surface (S), and various operational methods to facilitate greater versatility when performing hydrocarbon drilling related operations. The arrangement also comprises a sealing element (15, 16) to seal an annulus (5) of the riser (1), and a by-pass (17) around the sealing element (15, 16). Various methods makes it possible to switch between open mode and closed mode, and vice versa, monitoring leakage across the sealing element (15, 16), as well as performing other operations exploiting the advantages of the two different modes.

In a method for quantifying a volumetric flow rate of a flow of drilling mud in a floating structure for subsoil drilling, a flowmeter and a detection device are provided on a floating structure for subsoil drilling. The flowmeter generates a flow signal. The detection device generates a heave signal representative of a vertical heave of the floating structure. A processor transforms the flow signal into a first spectrum in the frequency domain and the heave signal into a second spectrum in the frequency domain. The processor compares the first spectrum with the second spectrum, obtaining a resultant spectrum. The processor transforms the resultant spectrum into a resultant signal in the time domain. The processor determines a mean value of the flow signal, adds the resultant signal to the mean value, obtaining a quantification of a flow of drilling mud in the floating structure.

An additive composition includes a rheology modifier selected from alcohol ethoxylates, amine ethoxylates, or ethylene oxide/propylene oxide copolymers, wherein the rheology modifier has an HLB ranging from about 4 to 10; and a winterizing agent that is at least one aliphatic non-ionic surfactant that has a branched structure and/or includes at least one unsaturation, wherein the winterizing agent has an HLB value between about 8 and 10.5.

A well system includes a drilling vessel, a concentric drillstring extending from the vessel into a subterranean wellbore disposed beneath a mudline, wherein the concentric drillstring is configured to circulate a drilling fluid from the drilling vessel into the wellbore along a first passage, and to circulate the drilling fluid from the wellbore to the drilling vessel along a second passage, and a subsea pump in fluid communication with the wellbore, wherein the subsea pump is configured to manage fluid pressure in the wellbore by controlling a height of a column of hydrostatic fluid disposed in the wellbore.