Drilling fluids fluid loss

R. Williamson. Well drilling fluids, fluid loss additives therefor and preparation of such additives. Patent GB 2178785, 1987. 

Uses Primary emulsifier for invert drilling fluids fluid loss control agent, stabilizer, rheology control agent for invert muds (in conjunction with sec. emulsifiers) Features Most effective when neutralized with lime Properties Dk, vise, liq, sol, in oil insol. in water sp.gr. 0.93 vise. < 10 cps (20 C) ... 

C. P. Anderson, S. A. Blenkinsopp, F. M. Cusack, and J. W. Costerton. Drilling mud fluid loss—an alternative to expensive bulk polymers. In Proceedings Volume, pages 481—489. 4th Inst Gas Technol Gas, Oil, Environ Biotechnol Int Symp (Colorado Springs, CO, 12/9-12/11),... 

Polyacrylamides are used in many other oilfield appUcations. These include cement additives for fluid loss control in well cementing operations (127), viscosity control additives for drilling muds (128), and fracturing fluids (129). Copolymers [40623-73-2] of acrylamide and acrylamidomethylpropanesulfonic acid do not degrade with the high concentrations of acids used in acid fracturing. 

Rheological Classification of Drilling Fluids 829. Flow Regimes 830. Principle of Additive Pressures 834. Friction Pressure Loss Calculations 836. Pressure Loss Through Bit Nozzles 839. 

Dispersed Noninhibited Systems. Drilling fluid systems typically used to drill the upper hole sections are described as dispersed noninhibited systems. They would typically be formulated with freshwater and can often derive many of their properties from dispersed drilled solids or bentonite. They would not normally be weighted to above 12 Ib/gal and the temperature limitation would be in the range of 176-194°F. The flow properties are controlled by a deflocculant, or thinner, and the fluid loss is controlled by the addition of bentonite and low viscosity CMC derivatives. 

In oil-producing formations with high fluid loss, drilling in with foam and foam completion proves beneficial. Usually, these formations cannot stand a column of water—so it is impossible to establish returns with conventional mud. The use of foam for drilling in and completion results in substantial increases in production. 

The wellbore, drill string and drilling fluid data from the previous example are used. Casing depth is 4,000 ft. Assuming a drill pipe length of 5,000 ft and a drill collar length of 500 ft, find the friction pressure losses. 

Integrating Equation 4-116 assuming incompressible drilling fluid flow (p is constant) and after simple rearrangements yields the pressure loss across the bit Apj (psi) which is... 

Drilling fluid type and properties (density, viscosity, fluid loss, etc., solids content, differential pressure, etc.)... 

Basically all formations penetrated during drilling are porous and permeable to some degree. Fluids contained in pore spaces are under pressure that is overbalanced by the drilling fluid pressure in the well bore. The bore-hole pressure is equal to the hydrostatic pressure plus the friction pressure loss in the annulus. If for some reason the borehole pressure falls below the formation fluid pressure, the formation fluids can enter the well. Such an event is known as a kick. This name is associated with a rather sudden flowrate increase observed at the surface. 

Avoid using concentrations high enough to lead to the loss of other desirable characteristics of the drilling fluid. 

Polyethercyclicpolyols possess enhanced molecular properties and characteristics and permit the preparation of enhanced drilling fluids that inhibit the formation of gas hydrates prevent shale dispersion and reduce the swelling of the formation to enhance wellbore stability, reduce fluid loss, and reduce filter-cake thickness. Drilling muds incorporating the polyethercyclicpolyols are substitutes for oil-based muds in many applications [195-197,1906,1907]. Polyethercyclicpolyols are prepared by thermally condensing a polyol, for example, glycerol to oligomers and cyclic ethers. 

Fluid loss additives are also called filtrate-reducing agents. Fluid losses may occur when the fluid comes in contact with a porous formation. This is relevant for drilling and completion fluids, fracturing fluids, and cement slurries. 

One of the basic mechanisms in fluid loss prevention is shown in Figure 2-1. The fluid contains suspended particles. These particles move with the lateral flow out of the drill hole into the porous formation. The porous formation acts like a sieve for the suspended particles. The particles therefore will be captured near the surface and accumulated as a filter-cake. 

Predictions on the effectiveness of a fluid loss additive formulation can be made on a laboratory scale by characterizing the properties of the filter-cake formed by appropriate experiments. Most of the fluids containing fluid loss additives are thixotropic. Therefore the apparent viscosity will change when a shear stress in a vertical direction is applied, as is very normal in a circulating drilling fluid. For this reason, the results from static filtering experiments are expected to be different in comparison with dynamic experiments. 

A composition containing polyanionic cellulose and a synthetic polymer of sulfonate has been tested for reducing the fluid loss and for the thermal stabilization of a water-based drilling fluid for extended periods at deep well drilling temperatures [812]. 

Hydroxyethylcellulose with a degree of substitution of 1.1 to 1.6 has been described for fluid loss control in water-based drilling fluids [1473]. An apparent viscosity in water of at least 15 cP should be adjusted to achieve an API fluid loss of less than 50 ml/30 min. Crosslinked hydroxyethylcellulose is suitable for high-permeability formations [344,346]. 

A crosslinked starch was described as a fluid loss additive for drilling fluids [632,1626]. The additive resists degradation and functions satisfactorily after exposure to temperatures of 250° F for periods of up to 32 hours. To obtain crosslinked starch, a crosslinking agent is reacted with granular starch in an aqueous slurry. The crosslinking reaction is controlled by a Brabender... 

Viscometer test. Typical crosslinked starches are obtained when the initial rise of the viscosity of the product is between 104° and 144° C, and the viscosity of the product does not rise above 200 Brabender units at temperatures less dian 130° C. The crosslinked starch slurry is then drum-dried and milled to obtain a dry product. The effectiveness of the product is checked by the API Fluid Loss Test after static aging of sample drilling fluids containing the starch at elevated temperatures. The milled dry product can then be incorporated into the oil well drilling fluid of the drill site. 

Compositions containing mixtures of metal hydroxides a polysaccharide, partially etherified with hydroxyethyl and hydroxypropyl groups, are used as fluid loss additives for aqueous, clay-mineral-based drilling muds [1437]. 

A polymeric composition for reducing fluid loss in drilling muds and well cement compositions is obtained by the free radical-initiated polymerization of a water-soluble vinyl monomer in an aqueous suspension of lignin, modified lignins, lignite, brown coal, and modified brown coal [705,1847]. The vinyl monomers can be methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinylacetate, methyl vinyl ether, ethyl vinyl ether, N-methylmethacrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, and additional AMPS. In this process a grafting process to the coals by chain transfer may occur. 

Adducts of aminoethylethanolamine and polyethylenepolyamines with humic acid-containing materials and fatty acids [1400] are useful as fluid loss additives in oil-based drilling fluids [854]. 

In addition, a fluid loss additive for oil-based drilling fluids, which consists of fatty acid compounds and lignite or humic acid, an oil-soluble or oil-dispersible amine or amine salt with phosphorie acid, or an aliphatic amide or hydroxyamide [392], has been described. 

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