Patent Application
20230399927
This invention applies to oil, gas, or water supply wells in the upstream hydrocarbon resource industry and in the municipal or agricultural water supply industries. CPC class E21B 43/122 and 43/123, methods for obtaining oil, gas, or water from wells, includes wells that require artificial lift to produce reservoir fluid and may use gas lift as the preferred method. International class E21B 43/12 and 34/10 includes gas lift wells and valves.
Subterranean wells are drilled through an oil, gas, or water supply reservoir and cased with a string of pipe. These wells have a tubing string of pipe, inside the casing, as the conduit for production of reservoir fluids to the wellhead and into the surface facility used to treat these fluids. If the well cannot flow naturally with reservoir pressure, then artificial lift is implemented to induce production fluid flow or to increase fluid flow. One artificial lift option is gas lift which uses a high-pressure gas source at the surface, usually compressed natural gas from the production facility but can be another gas such as plant processed natural gas, nitrogen, carbon dioxide, or air. Gas lift installations use valves that are positioned on the tubing string at various depths based on the injection pressure in the casing, production fluid pressure in the tubing, and control (kill) fluid pressure used to maintain hydrostatic control of the well during wellbore equipment installation. High-pressure injection gas is provided to the casing/tubing annulus to displace the control (kill) fluid out of the annulus, through each gas lift valve to the tubing, where the mixture of gas and tubing fluid is circulated to the wellhead and onward to the surface treating facility. The gas circulates through the uppermost first valve and continues displacing annulus fluid to the next deeper second valve. When gas begins to circulate through the second valve, the first valve must close for effective gas lift. The process of displacement continues to deeper valves, requiring sequential closing of each valve as gas circulates to the next deeper valve, until a deep point of gas injection is attained. One or multiple gas lift valves may be used depending on well depth and injection gas pressure.
The gas is injected into the casing/tubing annulus, transmitted through a gas lift valve into the tubing, and merged with reservoir production fluids to reduce the density. Reduced density of the mixture will reduce pressure at the bottom of the tubing column which enhances flow from the reservoir. An option provides gas injection into the tubing, passage through the gas lift valve, and production up the casing/tubing annulus.
Gas lift valves are controlled by an internal charge pressure, which in prior art is implemented at a surface shop and sealed prior to installation in the wellbore. This method requires knowledge of temperature at valve depth and, if a different internal charge pressure is desired, then the valve must be removed from the wellbore to be reset in the shop.
This invention provides surface control of the closing mechanism for each valve, which is the pneumatic tube control line with charging gas linked to the internal bellows/dome of the valve from the source at the surface (an option is one control line for each valve). Pressure is raised in the control line to close each valve, and because each is at a different depth, they will close in sequence by adjusting the control line pressure at the surface. When a well must be restarted after a shut-in period, the gas lift valves can be opened by reducing the control line pressure at the surface.
The control line of this invention is directly connected to the internal bellows/dome of the gas lift valve for tubing retrievable (conventional) method of valve installation. Side pocket mandrel installation has the control line connected to the mandrel which in turn transmits control pressure to the internal bellows/dome of the wireline gas lift valve, which has seals above and below. This control line invention can be used with injection pressure operated (IPO) or production pressure operated (PPO) valves. An option is an orifice at the deepest mandrel position that is not connected to the control line since it cannot close.
For this invention, charge gas (natural gas, nitrogen, carbon dioxide, air, or other fluid) supplied to the pneumatic tube control line would pass through a surface controller consisting of a pressure regulator and may include a desiccator or other devices. In addition, wellbore pressure sensors or distributed temperature sensing (DTS) lines could be installed independently of this invention.
This invention with a control line connection from surface to the gas lift valve eliminates the sealed chamber and need for temperature knowledge since the internal valve pressure is adjusted at the surface to close the valve or to open the valve, which also eliminates the need to pull a valve out of the well. The pneumatic tube control line with charging gas is directly connected to a tubing retrievable (conventional) valve or is connected to the side pocket mandrel which transmits pressure between seals on the wireline retrievable valve. Control to close or open all gas lift valves is from the pressure regulator at the surface via the control line connected to each valve, either directly or to the side pocket mandrel with pressure transmission to the valve.
This invention applies to oil, gas, or water supply wells in the upstream hydrocarbon resource industry and in the municipal or agricultural water supply industries. CPC class E21B covers obtaining oil, gas, water, or other materials from wells. Subclass 43 under well equipment or well maintenance covers obtaining fluids from wells, which includes 43/122 lifting well fluids and 43/123 gas lift. These methods for obtaining oil, gas, or water from wells includes wells that require artificial lift to produce reservoir fluid and may use gas lift as the preferred method. International class E21B 43/12 and 34/10 includes gas lift wells and valves.
The gas lift system that incorporates this invention is prior art with natural gas gathering from the production facility, compression, dehydration to remove water vapor, distribution to the various wells, measurement, and control of injection gas into each well for purposes of optimum allocation of gas. Options to natural gas from the production facility are processed natural gas from a plant, nitrogen, carbon dioxide, or air for water supply wells. Most installations in the prior art use valves that are pressure charged with nitrogen in the shop and sealed, which requires knowledge of the temperature in the wellbore at the depth of the valve when it is placed in operation because internal valve pressure varies with the change in temperature. Removal of the valve from the well to implement a different desired charge pressure requires a workover rig if tubing retrievable mandrels are used, or a wireline operation if side pocket mandrels are used.
The prior art for gas lift valve internal charge pressure uses depth related data for gas pressure in the annulus, production fluid pressure in the tubing, and temperature of each valve to calculate the internal charge pressure into the bellows/dome of the valve. The calculated pressure is applied to the valve in the shop and sealed, with nitrogen commonly utilized as the charging gas. The internal charge pressure into the bellows/dome of each valve is designed to close each in sequence from top to bottom, which requires a decline in casing pressure, observed at the surface, that enables each to close. This prior art design method reduces casing pressure which can limit depth of injection diminishing the effectiveness of gas lift and since each valve is pressure charged at surface and sealed, the valve must be pulled out of the well if a different internal charge pressure is desired. This design disadvantage of pulling valves to change the internal charge pressure is being addressed with a method of control from the surface.
Surface control options include electrical line or conduit and electrically controlled valve, hydraulic lines to a piston or bellows in the valve, acoustic link from valve to the surface, and this invention's pneumatic tube control line linking internal bellows/dome of the valve to a surface source of charge gas, which could be natural gas, nitrogen, carbon dioxide, air, or other fluid.
Gas lift installations use valves that are positioned on the tubing string at various depths based on the injection pressure in the casing, production fluid pressure in the tubing, and control (kill) fluid pressure used to maintain hydrostatic control of the well during wellbore equipment installation). This invention has a control line tube transmitting charge gas pressure from the surface directly to the valve.
