A method and equipment for harvesting natural gas from seabed hydrates are disclosed. The preferred equipment includes a mobile riser, a water injection nozzle, a gas collector, a gas separator, a gas compressor, a water pump, and a water boiler. A fraction of produced gas is used to heat water which is in turn injected to seafloor for dissociating gas hydrates. The preferred method of the invention comprises producing natural gas from seabed hydrates using a production ship with a moving riser installed. This method eliminates the need of drilling wells and thus cuts cost of gas production tremendously.

A hydrate solid-state fluidization mining method and system under an underbalanced reverse circulation condition are used for solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure includes an earlier-stage construction process, pilot hole drilling construction process, reverse circulation jet fragmentation process, underbalanced reverse circulation fragment recovery process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced reverse circulation method. Problems such as shaft safety, production control and environmental risks faced by conventional natural gas hydrate mining methods such as depressurization, heat injection, agent injection and replacement are effectively solved. By using the method, the weak-cementation non-rock-forming natural gas hydrates in the seafloor can be mined in environment-friendly, efficient, safe and economical modes, more energy resources can be provided, and energy shortage dilemmas are solved.

An offshore drilling vessel includes a floating hull having a moonpool, a drilling tower positioned on the hull at or near the moonpool, a tubular string main hoisting device including a main hoisting winch and main cable connected to the main hoisting winch, a crown block mounted on the drilling tower, a travelling block suspended from the crown block in a multiple fall arrangement of the main cable, a mobile working deck and an integrated heave compensation system including a main cable heave compensation sheave in a path of the main cable between the main hoisting winch and the travelling block, a hydraulic sheave compensator connected to the main cable heave compensation sheave to provide a heave compensated motion of the travelling block, and a hydraulic deck compensator connected to the hull and to the mobile working deck to provide a heave compensated motion of the working deck relative to the hull within the heave compensation motion range.

An abrasive suspension eroding system has an eroding unit (11), which can be lowered into an existing drilled hole (1), in order to generate a high-pressure erosion jet for the abrasive suspension eroding of material (6, 20) in an existing drilled hole (1). The eroding unit (11) can be connected to a drilling fluid line (9) and is configured to generate a high-pressure erosion jet from a drilling fluid abrasive suspension device.

A connection system for a managed pressure drilling system includes a connection hub flange that includes a plurality of pass-through ports and a plurality of connection hub flange ports. A connection hub ring is removably disposed around an outer surface of the connection hub flange. The connection hub ring includes a plurality of dogs configured to removably attach the connection hub ring to the outer surface of the connection hub flange and a plurality of stab-in connectors disposed around an outer surface of the connection hub ring. A ported bottom includes a plurality of bottom flange ports. A plurality of conduits connects the plurality of connection hub flange ports to the plurality of bottom flange ports. The plurality of stab-in connectors are connected to the plurality of connection hub flange ports by the plurality of pass-through ports.

An offshore drilling vessel includes a floating hull having a moonpool, a drilling tower positioned on the hull at or near the moonpool, a tubular string main hoisting device including a main hoisting winch and main cable connected to the main hoisting winch, a crown block mounted on the drilling tower, a travelling block suspended from the crown block in a multiple fall arrangement of the main cable, a mobile working deck and an integrated heave compensation system including a main cable heave compensation sheave in a path of the main cable between the main hoisting winch and the travelling block, a hydraulic sheave compensator connected to the main cable heave compensation sheave to provide a heave compensated motion of the travelling block, and a hydraulic deck compensator connected to the hull and to the mobile working deck to provide a heave compensated motion of the working deck relative to the hull within the heave compensation motion range.

The invention discloses a suction cylinder exploitation device and method for marine natural gas hydrates. The exploitation device comprises an exploitation cylinder, a water pump, a sand control device, a liquid-gas filling system and the like. Through the specially-designed exploitation cylinder and mating devices thereof, the exploitation cylinder can sink below a seabed surface to exploit natural gas hydrates deep below the seabed surface and can be withdrawn. A series of problems such as high well drilling and completion cost of traditional deep-sea drilling exploitation methods, and damage, collapses and sand generation of plain concrete wellbores under the effect of formation pressure are solved, and the limitations that traditional capping depressurization methods can only exploit submarine superficial hydrates and are low in exploitation efficiency are overcome. The invention can greatly reduce the exploitation cost of natural gas hydrates deep below the seabed surface and is of great significance for commercial exploitation of marine natural gas hydrates.

A method and equipment for harvesting natural gas from seabed hydrates are disclosed. The preferred equipment includes a mobile riser, a water injection nozzle, a gas collector, a gas separator, a gas compressor, a water pump, and a water boiler. A fraction of produced gas is used to heat water which is in turn injected to seafloor for dissociating gas hydrates. The preferred method of the invention comprises producing natural gas from seabed hydrates using a production ship with a moving riser installed. This method eliminates the need of drilling wells and thus cuts cost of gas production tremendously.

An offshore drilling vessel includes a floating hull having a moonpool, a drilling tower positioned on the hull at or near the moonpool, a tubular string main hoisting device including a main hoisting winch and main cable connected to the main hoisting winch, a crown block mounted on the drilling tower, a travelling block suspended from the crown block in a multiple fall arrangement of the main cable, a mobile working deck and an integrated heave compensation system including a main cable heave compensation sheave in a path of the main cable between the main hoisting winch and the travelling block, a hydraulic sheave compensator connected to the main cable heave compensation sheave to provide a heave compensated motion of the travelling block, and a hydraulic deck compensator connected to the hull and to the mobile working deck to provide a heave compensated motion of the working deck relative to the hull within the heave compensation motion range.

The present invention refers to a system and method for construction and completion of wells in the pre-salt production and injection fields. The application of the present invention allows a reduction in well construction time of approximately seven days considering the drilling and completion of the well. The system comprises string accessories, cement, AMB, production string, casings, HFIV, fluid, wellhead system, subsea equipment, DHSV and packer. The method aims at reducing one well phase, resulting in three drilling phases, with the running in of only two casings and the completion in an open well with part of the same exposed to the saline formation, herein called 2R-PAC.