The invention relates to the technical field of oil and gas drilling, and discloses an amphiphilic block polymer ultralow-permeability agent and an intelligent temporary plugging type water-based drilling fluid. The ultralow-permeability agent contains a structural unit provided by styryl hydrophobic monomer, maleic anhydride and acrylamide; the drilling fluid contains two or more of water, sodium bentonite, Pac-Lv, the ultralow-permeability agent, calcium carbonate, one-way plugging agent, white asphalt and barite which are stored in a mixed manner or independently stored. When the amphiphilic block polymer provided by the invention is used as the ultralow-permeability agent of the intelligent temporary plugging type water-based drilling fluid, the self-adaptive characteristic is realized; according to the amphiphilic block polymer, temporary plugging layer gaps formed in pore and throats by plugging materials in drilling fluid can be fully filled under the condition that the sizes and the distribution of the pore and throats of reservoirs are not required to be clear, so that the permeability of temporary plugging layer is greatly reduced, ultralow-permeability is realized, and the amphiphilic block polymer is weak in tackifying effect, has gel-improving effect and can improve the rheological property of the drilling fluid.

The invention relates to a method including a system of additives which increase fluidity and/or flow capacity and minimize pressure drops from the steps of lifting in production wells, collection lines, dehydration systems and ducts for transporting heavy and extra-heavy hydrocarbons. In addition, the injected system of chemical additives increases the dilution capacity of the solvents that need to be applied to improve the quality of the crude oil (reduce viscosity and density, and increase API gravity), thereby facilitating the dehydration and transport.

A process is provided for producing a biomass-derived rheology modifier, comprising: providing a pretreated feedstock comprising cellulose-rich solids; refining the cellulose-rich solids in a first high-intensity refining unit, generating refined cellulose solids; gelling the refined cellulose solids in a second high-intensity refining unit, thereby generating gelled cellulose solids; and homogenizing the gelled cellulose solids in a high-shear homogenizer, thereby generating a biomass-derived rheology modifier. The pretreated feedstock may include kraft pulp, sulfite pulp, AVAP® pulp, soda pulp, mechanical pulp, thermomechanical pulp, and/or chemimechanical pulp, derived from wood or lignocellulosic biomass. The pretreated feedstock may be GP3+® pulp, obtained from steam or hot-water extraction of lignocellulosic biomass. These rheology modifiers may be utilized in a wide variety of applications, including water-based or oil-based hydraulic fracturing fluid formulations, as gelling agents. These rheology modifiers are biodegradable, and their production does not directly involve chemicals other than biomass and water.

A process is provided for producing a biomass-derived rheology modifier, comprising: providing a pretreated feedstock comprising cellulose-rich solids; refining the cellulose-rich solids in a first high-intensity refining unit, generating refined cellulose solids; gelling the refined cellulose solids in a second high-intensity refining unit, thereby generating gelled cellulose solids; and homogenizing the gelled cellulose solids in a high-shear homogenizer, thereby generating a biomass-derived rheology modifier. The pretreated feedstock may include kraft pulp, sulfite pulp, AVAP® pulp, soda pulp, mechanical pulp, thermomechanical pulp, and/or chemimechanical pulp, derived from wood or lignocellulosic biomass. The pretreated feedstock may be GP3+® pulp, obtained from steam or hot-water extraction of lignocellulosic biomass. These rheology modifiers may be utilized in a wide variety of applications, including water-based or oil-based hydraulic fracturing fluid formulations, as gelling agents. These rheology modifiers are biodegradable, and their production does not directly involve chemicals other than biomass and water.

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.

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.

A surfactant of formula (I) ##STR00001## wherein each of R.sub.1 and R.sub.2 are independently a hydrogen, an optionally substituted alkyl, an optionally substituted cycloalkyl, or an optionally substituted arylalkyl, R.sub.3 and R.sub.4 are independently an optionally substituted alkyl, an optionally substituted cycloalkyl, or an optionally substituted arylalkyl, x is an integer in a range of 2-8, y is an integer in a range of 1-15, z is an integer in a range of 4-10, n is an integer in a range of 2-5, and A is one of a carboxybetaine group, a sulfobetaine group, or a hydroxy sulfobetaine group. An oil and gas well servicing fluid containing the surfactant and methods of servicing an oil and gas well are also described.

A very light weight, noncompressible drilling fluid including a very light weight hydrocarbon base liquid, and a styrenic butadiene diblock copolymer is heated to achieve excellent rheology including thixotropicity, making an effective drilling fluid with a density of 8 pounds per gallon or less. Densities as low as 4 pounds per gallon are achieved with the addition of glass bubbles. The glass bubbles may, but normally will not, exceed 50% by volume. A method of making the drilling fluid includes passing the light weight liquid and the copolymer through a cavitation device. The invention includes drilling and with and recirculating the fluid to maintain the desired density, viscosity and rheology by adjusting the ingredients accordingly. A method of managed pressure drilling employs the novel fluid, enabling control of drill pressure and physical properties of the fluid including equivalent circulating density.

Citrate polyester additives for crude oils, mixtures of the citrate polyester additives and crude oils, and methods for producing or forming the mixtures are provided. The mixtures and methods comprise at least one citrate polyester additive introduce or applied to crude oil, wherein the at least one citrate polyester additive comprises one or more citrate crosspolymers.

Citrate polyester additives for crude oils, mixtures of the citrate polyester additives and crude oils, and methods for producing or forming the mixtures are provided. The mixtures and methods comprise at least one citrate polyester additive introduce or applied to crude oil, wherein the at least one citrate polyester additive comprises one or more citrate crosspolymers.