Solvent mixtures for downhole elemental sulfur removal and formation stimulation, and methods for utilizing such solvent mixtures, are described herein. One method includes providing a solvent mixture that includes an elemental sulfur solvent fraction and an odorant fraction that includes a lactate ester solvent. The method also includes injecting the solvent mixture into a hydrocarbon well such that the elemental sulfur solvent fraction of the solvent mixture dissolves elemental sulfur deposited on well components, and contacting the solvent mixture with water such that the lactate ester solvent within the odorant fraction reacts with the water to generate lactic acid. The method further includes stimulating a formation through which the hydrocarbon well extends by flowing the solvent mixture including the lactic acid through the hydrocarbon well and into the formation.

The invention relates to the introduction of pressurized fluid, e.g. acid, into a subsea well directly from a vessel (33). A fluid injection assembly (20) is fitted to the top of a subsea Xmas tree (3), the assembly (20) including fail safe closed valve (21) which is controlled via a hydraulic line (31) from the vessel. The hose and assembly and valve are designed with an internal bore allowing a large diameter ball to be dropped (required for acid stimulation). The subsea subsea control module (8) on the Xmas tree is controlled from the producing platform.

The invention relates to the introduction of pressurized fluid, e.g. acid, into a subsea well directly from a vessel (33). A fluid injection assembly (20) is fitted to the top of a subsea Xmas tree (3), the assembly (20) including fail safe closed valve (21) which is controlled via a hydraulic line (31) from the vessel. The hose and assembly and valve are designed with an internal bore allowing a large diameter ball to be dropped (required for acid stimulation). The subsea subsea control module (8) on the Xmas tree is controlled from the producing platform.

A method for the stimulation of a hydrocarbon-bearing formation, said method comprising the steps of providing a wellbore in need of stimulation; inserting a plug in the wellbore at a location slightly beyond a predetermined location; inserting a perforating tool having an outside surface and a spearhead or breakdown acid composition into the wellbore, wherein said outside surface of said tool is pre-treated prior to downhole insertion with a grease containing a first corrosion inhibitor adapted to eliminate/minimize/reduce the corrosion inflicted upon it by the exposure of the acid for the duration of the fracking or stimulation and wherein said acidic composition comprises a second corrosion inhibitor which reacts with said first corrosion inhibitor to generate a corrosion protective layer onto said surface; positioning the tool at said predetermined location; perforating the wellbore with the tool thereby creating a perforated area; allowing the spearhead acid to come into contact with the perforated area for a predetermined period of time sufficient to prepare the formation for stimulation; removing the tool from the wellbore; and initiating the fracking of the perforated area using a stimulation fluid. Also disclosed is a corrosion inhibiting compound or composition for use with the acid composition.

A method for the stimulation of a hydrocarbon-bearing formation, said method comprising the steps of providing a wellbore in need of stimulation; inserting a plug in the wellbore at a location slightly beyond a predetermined location; inserting a perforating tool having an outside surface and a spearhead or breakdown acid composition into the wellbore, wherein said outside surface of said tool is pre-treated prior to downhole insertion with a grease containing a first corrosion inhibitor adapted to eliminate/minimize/reduce the corrosion inflicted upon it by the exposure of the acid for the duration of the fracking or stimulation and wherein said acidic composition comprises a second corrosion inhibitor which reacts with said first corrosion inhibitor to generate a corrosion protective layer onto said surface; positioning the tool at said predetermined location; perforating the wellbore with the tool thereby creating a perforated area; allowing the spearhead acid to come into contact with the perforated area for a predetermined period of time sufficient to prepare the formation for stimulation; removing the tool from the wellbore; and initiating the fracking of the perforated area using a stimulation fluid. Also disclosed is a corrosion inhibiting compound or composition for use with the acid composition.

A method for providing simultaneous gas-solid or gas-solid slurry mixture chemical well stimulation of hydraulically fractured oil and gas-condensate wells in shales according to the present invention is disclosed. Injected with gas, chemicals having interacted with in-situ water alter rock properties near the fractures/fissures allowing liquids to move better, thus enlarging the swept volumes and recovery factor. The injected gas-solid mixture or gas-solid slurry mixture re-opens fractures that were closed previously due to well depletion and pressure dropping below fracture closure pressure. The process results in greater relative permeability (flow through the larger pores) which leads to more mobile fluids and greater production rates.

A method for providing simultaneous gas-solid or gas-solid slurry mixture chemical well stimulation of hydraulically fractured oil and gas-condensate wells in shales according to the present invention is disclosed. Injected with gas, chemicals having interacted with in-situ water alter rock properties near the fractures/fissures allowing liquids to move better, thus enlarging the swept volumes and recovery factor. The injected gas-solid mixture or gas-solid slurry mixture re-opens fractures that were closed previously due to well depletion and pressure dropping below fracture closure pressure. The process results in greater relative permeability (flow through the larger pores) which leads to more mobile fluids and greater production rates.

Methods for the fracking or stimulation of a hydrocarbon-bearing formation are provided in multiple embodiments. According to one method, it comprises the steps of: providing a wellbore having a casing; inserting a plug in the wellbore at a predetermined location; inserting a perforating tool and an acidic composition into the wellbore; wherein the acidic composition includes a corrosion inhibiting composition comprising at least two compounds selected from: Group A-I, and wherein at least two compounds are selected from different groups of the Groups A-I.

Methods for the fracking or stimulation of a hydrocarbon-bearing formation are provided in multiple embodiments. According to one method, it comprises the steps of: providing a wellbore having a casing; inserting a plug in the wellbore at a predetermined location; inserting a perforating tool and an acidic composition into the wellbore; wherein the acidic composition includes a corrosion inhibiting composition comprising at least two compounds selected from: Group A-I, and wherein at least two compounds are selected from different groups of the Groups A-I.

Systems and methods are directed to proppant flowback control. A method includes coating resin onto proppant at a well site and pumping the coated proppant into a wellbore during a fracking operation. The method further includes pumping an activator for the resin into the wellbore to displace the coated proppant into at least one fracture during the fracking operation. The pumping of the coated proppant and the pumping of the activator are performed separately.