A method of surface logging a well includes adding each of multiple polymeric taggants to a circulating drilling fluid in an addition sequence while drilling the well. Each polymeric taggant includes a polymer and a respective fluorescent dye having an emission wavelength or excitation wavelength different from that of each other fluorescent dye. The method includes taking a sample of drill cuttings carried by a drilling fluid while drilling a well, wherein the sample of drill cuttings includes polymeric taggants attached to the drill cuttings. The method includes extracting the dyes from the sample of drill cuttings into an extract solution; determining an indication of the type of and the concentration of each of the dyes in the extract solution; and determining a depth associated with the sample of drill cuttings based on the indication of the concentration of each of the dyes and on the addition sequence.

A variety of methods and systems are disclosed, including, in one embodiment, a method for emulsion breaking including: applying a trigger to an oilfield emulsion to facilitate breaking of the oilfield emulsion, wherein the oilfield emulsion includes an oleaginous phase, a non-oleaginous phase, and a breakable emulsifier, wherein the trigger breaks the breakable emulsifier into non-emulsifying byproducts; and separating at least a portion of the oleaginous phase from the non-oleaginous phase.

Cementing compositions containing a hydraulic cement, halloysite nanoparticles, and silica flour. The cementing compositions may optionally include other additives such as a friction reducer, a defoamer, and a fluid loss additive. Cement samples made therefrom and methods of producing such cement samples are also specified. The addition of halloysite nanoparticles and silica flour provides enhanced mechanical strength (e.g. compressive strength, flexural strength) and improved durability (e.g. resistance to CO.sub.2 and salinity) to the cement, making them suitable cementing material for oil and gas wells.

A composition including a coated nanoparticle and an ion, wherein the coated nanoparticle includes a nanoparticle, a linker, and a stabilizing group; methods of making and using the composition; and systems including the composition. The linker includes an anchoring group, a spacer, and a terminal group. The anchoring group is covalently bound to the nanoparticle and at least one of the terminal groups is covalently bound to at least one stabilizing group. A composition including a crosslinked-coated nanoparticle and an ion, wherein the crosslinked-coated nanoparticle includes a nanoparticle and a coating that includes a linker, a crosslinker, and a stabilizing group; methods of making and using the composition; and systems including the composition.

The present invention relates to new materials composed of reticulate polymer loaded with micro- or nano-loads which result in particles or microparticles to be used in fracking muds for secondary extraction of gas and oil.

A system for slowly releasing an oil-soluble well treatment agent into a well or a subterranean formation includes a composite of the oil-soluble well treatment agent associated with a second component. The amount of the oil-soluble well treatment agent in the composite is from 20 to 35 weight percent and the average particle size of the oil-soluble well treatment agent in the composite is less than or equal to 1 micrometer. The composite may further contain a water-soluble well treatment agent.

A wellbore fluid comprising a first aqueous base fluid and a plurality of silica nanoparticles suspended in the first aqueous base fluid. The nanoparticles are present in the fluid in an amount to have an effect of decreasing a crystallization temperature by at least 4 to 55° F. as compared to a second aqueous base fluid without the silica nanoparticles.

The present invention relates to the petroleum drilling fluid field, and discloses a modified silicon dioxide nano-particle comprising a modifying polymer chain composed of structural units provided by one or more of monomers represented by the following formula (1) and one or more of monomers represented by the following formula (2). The present invention provides a method for preparing modified silicon dioxide nano-particles and a drilling fluid suitable for shale gas wells containing the modified silicon dioxide nano-particles as a plugging agent. When the modified silicon dioxide nano-particles provided in the present invention are used as a plugging agent in a drilling fluid, they will not agglomerate into large-size particles, and can achieve a good plugging effect. ##STR00001##

The present invention relates to the well drilling field in petrochemical industry, and discloses a high-density water-based drilling fluid suitable for horizontal shale gas wells comprising a nano-plugging agent, a bionic wall bracing agent, a bionic shale inhibitor, a filler, an emulsifier, and an amphiphobic wettability reversal agent, wherein, the nano-plugging agent is modified silicon dioxide nano-particle, and its modifying group includes a modifying copolymer chain; the bionic wall bracing agent is carboxymethyl chitosan with a dopamine-derived group grafted on its main chain; the bionic shale inhibitor is composed of structural units of arginine and structural units of lysine; the filler consists of calcium carbonate of 1,600-2,500 mesh, calcium carbonate of 1,050-1,500 mesh, and calcium carbonate of 500-1,000 mesh at a weight ratio of 1:0.55-6:0.55-6; and the amphiphobic wettability reversal agent is a dual-cation fluorocarbon surfactant. The drilling fluid provided herein is suitable for use in shale gas mining.

Provided herein is a hydraulic fracturing fluid containing enzyme encapsulated hydrogel nanoparticles and a breaker composition of a viscosifier-degrading enzyme encapsulated in the hydrogel nanoparticle. Also provided are methods for hydraulic fracturing utilizing hydrogel nanoparticles encapsulating an enzyme as a breaker to prevent the premature degradation of the fracturing fluid, to improve transport and placement of the proppant and to facilitate subsequent cleaning of the fracturing fluid.