A method of mitigating lost circulation in a subterranean wellbore for oil and gas includes introducing basaltic particles and a carbonated mixture to the lost circulation zone of the subterranean wellbore, contacting the basaltic particles with the carbonated mixture, dissolving at least a part of the basaltic particles with the carbonated mixture, reacting divalent cations with the carbonate anions in the carbonated mixture to produce carbonate minerals, providing stimulus to the basaltic particles and the carbonated mixture, depositing at least a part of the carbonate minerals to fractures of the lost circulation zone, monitoring the reacting and depositing; and optionally repeating one or more of the aforementioned steps. A drilling system for oil and gas extraction includes basaltic particles, a carbonated mixture, at least one stimulus generator, and a mitigation device.

An apparatus to simulate fluid loss through vugs in formations includes a housing defining an inner volume, and having a first end and a second end. The inner volume represents an inner region of a wellbore formed in a formation containing a vugular loss zone. The housing can receive wellbore fluid within the inner volume. A first cover late, which sealingly covers the first end, represents a first volumetric boundary of the inner region of the wellbore. A second cover plate, which sealingly covers the second end, represents a second volumetric boundary of the inner region of the wellbore. An outlet in the second cover plate can be switched between open and closed states. The outlet in the open state represents a vug in the inner wall of the wellbore. The apparatus includes a pressure port configured to transmit fluidic pressure in a direction of gravity within the inner volume and to apply the fluidic pressure to the wellbore fluid within the inner volume.

A method of drilling a subterranean geological formation is described. The method includes driving a drill bit to form a wellbore into the subterranean geological formation thereby producing a formation fluid including hydrogen sulfide (H.sub.2S). The method includes injecting a drilling fluid into the subterranean geological formation through the wellbore. The drilling fluid composition includes 0.25 to 2 wt. % of a primary H.sub.2S scavenger, which is potassium permanganate, and an invert emulsion, which includes a continuous phase including a vegetable oil which is at least one selected from the group consisting of corn oil, soybean oil, rapeseed oil, canola oil, sunflower oil, safflower oil, peanut oil, and cottonseed oil and a dispersive phase including water. The potassium permanganate present in the drilling fluid composition reacts with the H.sub.2S present in the formation fluid to produce a dispersion of manganese-containing particles which are at least one selected from the group consisting of manganese sulfide and manganese sulfate.

A protective tubular is run downhole into a wellbore in a subterranean formation. A non-metallic tubular is disposed within the protective tubular. The non-metallic tubular includes an adapter. The adapter includes a spring-loaded latch, a ball seat, a shear pin, and a ball catcher. While intact, the shear pin holds a position of the non-metallic tubular relative to the protective tubular. A ball is used to shear the shear pin of the adapter, thereby allowing the non-metallic tubular to move relative to the protective tubular. Pressure is applied to the ball to move the non-metallic tubular relative to the protective tubular. The non-metallic tubular is coupled to the protective tubular using the spring-loaded latch of the adapter. Pressure is applied to the ball to shear the ball seat of the adapter. A fluid is flowed into the non-metallic tubular through an opening defined by the adapter.

A treatment fluid can include: a base fluid, wherein the base fluid comprises water; and a lost-circulation material, wherein the lost-circulation material comprises a polymer network having at least one branching point formed with a monomer and a cross-linking agent that comprises at least three active functional groups. The treatment fluid can maintain a pressure differential of at least 1 psi when tested with a cylindrical void that has a diameter of 0.02 inches. The monomer can be a vinyl ester-based monomer that is polymerized with the cross-linking agent to form the polymer network. The treatment fluid can be used in an oil and gas operation.

A lost circulation material (LCM) having flakes formed from waste vehicle tires. The LCM includes flakes produced from waste vehicle tires processed to remove steel components of the tires and produce flakes having a specific size. Also, methods of lost circulation control and manufacture of the waste vehicle tire LCM.

A circulating downhole tool utilising a variable fluid pressure regulated cycle valve device that can be attached to the borehole assembly BHA of a coiled tubing and used down an offshore or onshore wellbore is disclosed. The circulating downhole tool utilising a variable fluid pressure regulated cycle valve device can be remotely operated by an operator on the surface as many times as required in either the through-flow, intermediary or circulatory modes-of-operation, by simply varying the drilling fluid flow rate and pressure being supplied from the pump located on the surface and interconnected to the coiled tubing and the BHA that will include the circulating downhole tool utilising a variable fluid pressure regulated cycle valve device.

Branched and crosslinked polymeric fluid loss control agents and methods are provided that have at least one acrylamide-based monomer, at least one sulfonated anionic monomer, and at least one crosslinking monomer. The at least one acrylamide-based monomer and the at least one sulfonated anionic monomer are crosslinked. The branched and crosslinked polymeric fluid loss control agents have between 50 and 99 mol % of the at least one acrylamide-based monomer, between 1 and 30 mol % of the at least one sulfonated anionic monomer, and between 0.1 and 10 mol % of the at least one crosslinking monomer.

Methods and compositions for servicing a wellbore and, in certain embodiments, to the use of compositions in a wellbore to mitigate lost circulation. In some embodiments, the methods include providing a treatment fluid that includes an aqueous base fluid, a lost circulation material, and a rheology modifier that includes a nanocellulose material; introducing the treatment fluid into a wellbore penetrating at least a portion of a subterranean formation including a loss zone; and allowing the treatment fluid to rapidly defluidize in the loss zone.

Compressed lost circulation materials for use in subterranean formations are provided. In some embodiments, the methods include: introducing a treatment fluid that includes a base fluid and a compressed lost circulation material into a wellbore penetrating at least a portion of a subterranean formation including a loss zone, the compressed lost circulation material including a binding material and a compressed material; allowing the binding material to at least partially degrade or dissolve; and allowing the compressed lost circulation material to at least partially expand in the subterranean formation.