A downhole transducer assembly capable of being safely operated at a variety of pressures and depths may include a turbine rotatable by a fluid pressure differential rotationally fixed to a rotor in a generator. To reduce the rotational speed of the turbine and rotor, a pressure regulator may limit a fluid pressure differential by controlling the volumetric flow. One or more nozzles may be configured to automatically regulate a nozzle diameter, and therefore the pressure drop across the nozzle. A surge protector may be connected to the generator.

The invention relates to the use of a casing or liner (3) with pre-formed, selectively openable apertures (5), in plug and abandon operations at the end of life of a hydrocarbon well. The casing or liner (3) is installed at the start of the well's life and the apertures (5) are provided over a length of the casing/liner above the reservoir where a permanent plug would normally be formed when the well is abandoned at the end of its life. Associated with the apertures are sliding sleeve closure members (6) which are designed to remain operational over the 20-30 year lifetime of the well.

Disclosed is a cavity creation tool by crushing with multi-stage controllable water jet, which is used in natural gas hydrate development. The tool mainly consists of an inner tube upper joint, an inner tube lower joint, an intermediate sleeve, an inner structure consisting of a coaxial throttle push rod, an outer layer sleeve, an outer layer structure consisting of a supporting ring, a jet head mounted to the intermediate sleeve and threading the outer layer sleeve, and a jet crushing structure consisting of a single stage telescopic jet head and a second stage telescopic jet head.

Well systems including a wellbore lined with a wellbore lining and a pressure booster extendable within the wellbore on a conveyance whereby an annulus is defined between the conveyance and the wellbore lining. The pressure booster includes a body having a first end coupled to the conveyance, a jetting chamber defined within the body, one or more flow ports defined in the body and providing fluid communication between the jetting chamber and the annulus, and a jet nozzle in fluid communication with the conveyance. The pressure booster receives a first fluid through the conveyance and a second fluid from the annulus and mixes the first and second fluids to discharge a fracturing fluid below the pressure booster at a pressure greater than a pressure within the annulus above the pressure booster.

Overbalanced drilling (OBD) is known to be cheap and simple but formation damage and reduced rate of penetration (ROP) are some of its disadvantages. However, underbalanced drilling (UBD) minimizes formation damage and achieve high ROP, but it is expensive, complex and can't be applied in many cases.

This application introduces a new technique that incorporates the advantages and avoids the disadvantages of these drilling systems and is referred to as Dynamic Underbalanced Drilling (DUBD).

In DUBD a pressure drop at the environ of the bit, below and around, is created that is restored to normal pressure above the bit and such conditions requires some minor modifications to the design of drill bit. Thus at the zone located below and around the bit underbalance conditions are dominated while the rest of the hole is overbalanced.

The anticipated cost of this technique is nearly zero and it is expected to save much of drilling costs. DUBD is expected to provide higher ROP that may exceed ordinary UBD in some cases, so saves time, reduce formation damage, saves costs (cheaper than OBD) and enables gathering information about the reservoir while drilling. This can save some of logging and testing costs. In addition, DUBD may reduce drilling problems, particularly time sensitive problems, and overcome problems of UBD. Furthermore, it can be used safely in over pressurized shale and salt formations, where UBD is not recommended.

An exploiting method and device of marine facies natural gas hydrate. The exploiting method comprises the following steps: (1) after the construction of a vertical well, a fixed pipe is constructed, the exploiting well is set in the center of the fixed pipe, and the mixture is filled between the inner wall of the fixed pipe and the outer wall of the exploiting well; (2) the self-excited oscillating jet nozzle enters the exploiting well along the vertical well to the designated position through an orifice on the exploiting well and sprays the mixture, so that the mixture is broken evenly to form artificial fractures; (3) under the corresponding temperature, the hydrate decomposes to produce gas by depressurized exploiting; (4) the gas-liquid mixture exploited by the exploiting well is separated into liquid and gas in the gas-liquid separation device to collect liquid and gas.

An in-situ hydraulic jet exploiting device and method of a low-permeability natural gas hydrate reservoir. The device includes a high-pressure reaction kettle configured for formation, fracturing and exploiting of a hydrate, a stable-pressure gas supply module configured to adjust and control a gas flow rate, a constant-speed constant-pressure liquid supply module configured to control a liquid flow rate or keep liquid injection pressure constant, a thermostatic water bath configured to provide a constant-temperature environment for a device system, a back-pressure module configured to automatically control an exploiting rate or exploiting pressure, an in-situ hydraulic jet permeability enhancement module, a data collection and processing module configured to collect and process basic system parameters, and a pipeline connecting various components.

A method of manufacturing a valve of a tool for use downhole includes changing a flow characteristic of the valve. A load is applied to a first nozzle secured in a housing of the valve via a first release member, wherein a magnitude of the load is greater than a release threshold of the first release member, to release the first release member. The first nozzle is removed from the housing, and a second nozzle is secured in the housing via a second release member.

A multi-functional jetting tool can be installed within a tubular work string, or attached to the distal or leading end of the tubular work string, in order to facilitate improved cleaning of downhole and/or subsea equipment—and particularly equipment with internal recesses, cavities or crevasses. A bull nose cap member, which can be constructed of plastic or other non-abrasive material, can be attached when the jetting tool is run on the distal end of a tubular work string. Fluid jetting ports can be selectively equipped with standard-sized or adjustable nozzles, thereby permitting customized fluid jet flow pattern from the jetting tool along the tool body in multiple directions for desired applications.

The invention relates to a method of conducting a perf wash cement (“P/W/C”) abandonment job in an offshore oil or gas well annulus (2), in particular the washing or cementing operation using a rotating head (6, 8) with nozzles (7, 9) dispensing wash fluid or cement at pressure. Certain values of parameters of a washing or cementing job have been found surprisingly to affect the quality of the job, or the degree to which they affect the quality of the job has been unexpected. These include including rotation rate of the tool, the direction of translational movement of the tool, and the volume flow rate and pressure per nozzle of cement or wash fluid (and hence nozzle size).