Patent Application
20100206568
The present application relates generally to gas well dewatering systems. More particularly, the present application relates to equalization of pressure in a gas well to allow for easier retrieval of a dewatering pump.
Hydrocarbons and other fluids are often contained within subterranean formations at elevated pressures. Wells drilled into these formations allow the elevated pressure within the formation to force the fluids to the surface. However, in low pressure formations, or when the formation pressure has diminished, the formation pressure may be insufficient to force the fluids to the surface. In these cases, a positive displacement pump, such as a piston pump, can be installed to provide the required pressure to produce the fluids.
The function of pumping systems in gas wells is to produce liquid, generally water, that enters the wellbore naturally with the gas. This is typically necessary only on low-flow rate gas wells. In high-flow rate gas wells, the velocity of the gas is usually sufficient that it carries the water to the surface. In low-flow rate wells, the water accumulates in the wellbore and restricts the flow of gas. By pumping out the water, the pump allows the well to flow at a higher gas rate, and this additional produced gas, which eventually is related to additional revenue, pays for the pumping unit.
Operation of the pumping unit can create an area of low pressure beneath the pump compared to high pressure on top of the pump. The differential pressure can become great enough so as to prevent retrieval of the pumping unit by normal means. For example, the differential pressure can result in a pulling force requirement greater than the axial strength of a cable supporting the unit in the well. Pulling up on the cable will thus cause either the cable or a separate shearing mechanism to shear, thus leaving the pumping unit without a connection uphole. For this purpose, the pumping unit can include a fishing neck profile for retrieval using a separate fishing tool. However, without a means for equalizing the differential pressure, retrieval with the fishing tool can also be difficult or impossible.
The present disclosure recognizes that it is desirable to provide devices, systems, and methods for equalizing pressure in a gas well to allow for easier retrieval of a dewatering pump deployed in the well between an area of low pressure and high pressure. It is recognized as desirable to provide such devices and systems that are durable and yet relatively inexpensive to manufacture, operate and repair.
Devices, systems and methods for equalizing pressure in a gas well are provided. In one example, a jar device is coupled to a pump deployed in a gas well between areas of low pressure and high pressure. The jar device includes a mandrel and a no-go sleeve. A jarring tool is operated to transfer an axial force onto the jar device that is large enough to shear a shearable connection between the mandrel and no-go sleeve and thereby cause the mandrel to slide from a first position to a second position with respect to the no-go sleeve. A seal that seals between the no-go sleeve and mandrel when the mandrel is located in the first position is unsealed as a result of the movement of the mandrel and fluid communication is thereby permitted between the areas of high pressure and low pressure. This allows for easier retrieval of the pump.
The best mode is described hereinbelow with reference to the following drawing figures.
In the following description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes only and are intended to be broadly construed. The different devices, systems and method steps described herein may be used alone or in combination with other devices, systems and method steps. It is to be expected that various equivalents, alternatives, and modifications are possible within the scope of the appended claims.
A locking ring 28 extends inwardly from the inner diameter of the no-go sleeve 18 and is configured to engage and lock with a locking groove 30 on the outer surface of the mandrel 16 to retain the mandrel 16 in the second position (
In use, the device 14 is coupled to a pump (not shown) deployed in a gas well between the areas 10, 12 of low pressure and high pressure. The areas 10, 12 of low pressure and high pressure are created by operation of the pump. When retrieval of the pump by manual or other means is required, the differential pressure between the areas 10, 12 works against the retrieval action, thus making it difficult to remove the pump from the well. The system shown in
Optionally, the lock ring 28 engages with the locking groove 30 as the mandrel 16 is moved into the second position (
An O-ring 68 forms a seal between an inner surface 70 of the no-go sleeve 58 and the outer surface 72 of the mandrel 56 when the mandrel 56 is located in the first position (
In use, the jar device 54 is coupled to a dewatering pump deployed in a gas well between the areas 50, 52. A jarring tool 53 such as spang jars and weight is operated to transfer an axial force in the direction of arrow 78 large enough to shear the shearable connection 60 and cause the mandrel 56 to move uphole in the direction of arrow 66 into the second position shown in
