This document relates to pumps with wear sleeves.
Wear sleeves are used in tubulars and in pumps for long term protection from wear due to contact with abrasive particles carried in treatment fluids.
A pump is disclosed, comprising: a pump block defining a cylinder in which a piston is mounted for reciprocation and positive displacement of fluids from an intake port of the pump block to a discharge port of the pump block; an intake valve located in the intake port of the pump block and a discharge valve located in the discharge port of the pump block; the intake valve having a valve plug that has a closed position in which the valve plug is seated on a valve seat in the intake port; a wear sleeve lining at least a portion of the intake port upstream of the valve seat; a pressure sensor upstream of the intake valve for detecting a pressure condition indicative of failure of the intake valve to provide a seal when the intake valve is in the closed position; and a controller responsive to the pressure sensor to send a signal to stop operation of the pump upon detection of the pressure condition.
In various embodiments, there may be included any one or more of the following features: The valve seat is conically tapered and the wear sleeve is disposed to intercept a set of lines, each line being tangent to the valve seat, that correspond to projected paths of a reverse flow jet that may form upon valve seal failure. The wear sleeve has a tapered inner surface. The tapered inner surface is concave. The tapered inner surface is scalloped. The tapered inner surface is linear. The discharge valve has a discharge valve plug that has a closed position in which the discharge valve plug is seated on a discharge valve seat in the discharge port and further comprising a discharge wear sleeve lining at least a portion of the discharge port upstream of the discharge valve seat. A pressure sensor is upstream of the discharge valve for detecting a pressure condition indicative of failure of the discharge valve to provide a seal when the discharge valve is in the closed position. The pump block defines plural cylinders and respective plural intake valves and discharge valves, and further comprising a manifold connected to supply treatment fluid to each intake port. The pressure sensor is located within the manifold. The pressure sensor is located within the intake port. The pressure sensor is located within a trunk of the manifold. The pressure sensor is located within an intake branch, of the manifold, connected to the intake port. The pump further comprises plural wear sleeves, with each wear sleeve lining at least a portion of the intake port upstream of the respective valve seat. The pump further comprises plural pressure sensors. Each pressure sensor is located upstream of the respective intake valve. One or more of the plural pressure sensors is located within the manifold. One or more of the plural pressure sensors is located within a respective intake port. The fluid is a fracturing fluid and the pump is connected to a source of the fracturing fluid. The fracturing fluid comprises gelled liquefied petroleum gas. The fracturing fluid comprises one or more of water, diesel oil, nitrogen, or other suitable fluids.
These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.
Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:
Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.
In the conventional fracturing of wells, producing formations, new wells or low producing wells that have been taken out of production, a formation can be fractured to attempt to achieve higher production rates. Proppant and fracturing fluid are mixed in a blender and then pumped into a well that penetrates an oil or gas bearing formation. High pressure is applied to the well, the formation fractures and proppant carried by the fracturing fluid flows into the fractures. The proppant in the fractures holds the fractures open after pressure is relaxed and production is resumed.
Care must be taken over the choice of fracturing fluid. The fracturing fluid must have a sufficient viscosity to carry the proppant into the fractures, should minimize formation damage and must be safe to use. A fracturing fluid that remains in the formation after fracturing is not desirable since it may block pores and reduce well production. For this reason, carbon dioxide has been used as a fracturing fluid because, when the fracturing pressure is reduced, the carbon dioxide gasifies and is easily removed from the well.
Various alternative fluids have been disclosed for use as fracturing fluids, including liquefied petroleum gas (LPG), which has been advantageously used as a fracturing fluid to simplify the recovery and clean-up of frac fluids after a frac. Exemplary LPG frac systems are disclosed in WO2007098606. However, LPG has not seen widespread commercial usage in the industry due to the perceived dangers associated with its use, and as a result conventional frac fluids such as water and frac oils continue to see extensive use.
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A danger associated with LPG use is the risk of inadvertent fluid breakout resulting in the release of a highly explosive plume of pressurized LPG fluids into the atmosphere surrounding the worksite. Breakouts may be caused by pipe corrosion from proppant laden LPG pumped at high pressures during a fracturing operation. Referring to
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Wear sleeve 36 effectively buys more time, relative to a system that doesn't incorporate wear sleeve 36, between seal failure and system breakout required for pressure sensor 48 to detect the pressure condition indicative of seal failure, allowing control signals from controller 50 to be sent to shut down pump 10 before system breakout. In some cases, wear sleeve 36 may resist breakout by only several seconds longer than without wear sleeve 36, provided that such added delay is sufficient for sensor 48 to detect the pressure condition. Because of the dynamic and intermittent nature of fluid flow through manifold 30 and pump 10, it may be difficult or impossible for sensor 48 to detect the pressure condition before breakout without the wear sleeve 36.
Wear sleeves 36 are conventionally used in high flow areas to provide long term protection against interior pipe wall erosion. For example, wear sleeves 36 have been used in locations such as at the discharge side 52 of discharge valve 24, where extreme shear pressures, turbulent fluid flow, or the redirecting by valve plug 26A of fluid flow laterally against discharge port walls 54 downstream of valve 24 may result in erosion of the discharge port walls 54 over an extended period of time if left unprotected. However, because of the high cost and generally brittle nature of wear resistant materials, such materials are not used across the entire interior surface of pump components or in flow areas expected to receive relatively little wear over time.
By contrast with conventional use of wear resistant materials and wear sleeves, the wear sleeve 36 disclosed herein is provided for short term support and is located in an area, namely the low pressure intake 18 of cylinder 14, expected to experience relatively low levels of long term wear. However, the combination of wear sleeve 36, pressure sensor 48, and controller 50 as disclosed afford effective protection against reverse jets of proppant laden fluid forming across the seal interface of valve 22.
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Although described above for a fracturing operation, pump 10 may be used for other treatment operations such as gravel packing Although valve seat 28 is described as being conically tapered, other tapered shapes may be used such as curved tapers, for example to seat a ball valve member (not shown). Although a piston or plunger type positive displacement pump is illustrated, other styles of positive displacement pump may be used, such as a progressive cavity pump. Although concave inner surfaces 40 (
LPG may include a variety of petroleum and natural gases existing in a liquid state at ambient temperatures and moderate pressures. In some cases, LPG refers to a mixture of such fluids. These mixes are generally more affordable and easier to obtain than any one individual LPG, since LPGs are hard to separate and purify individually. Unlike conventional hydrocarbon based fracturing fluids, common LPGs are tightly fractionated products resulting in a high degree of purity and very predictable performance. Exemplary LPGs include propane, butane, or various mixtures thereof. As well, exemplary LPGs also include isomers of propane and butane, such as iso-butane. Further LPG examples include HD-5 propane, commercial butane, and n-butane. The LPG mixture may be controlled to gain the desired hydraulic fracturing and clean-up performance. LPG fluids used may also include minor amounts of pentane (such as i-pentane or n-pentane), higher weight hydrocarbons, and lower weight hydrocarbons such as ethane.
LPGs tend to produce excellent fracturing fluids. LPG is readily available, cost effective and is easily and safely handled on surface as a liquid under moderate pressure. LPG is completely compatible with formations, such as oil or gas reservoirs, and formation fluids, is highly soluble in formation hydrocarbons, and eliminates phase trapping—resulting in increased well production. LPG may be readily viscosified to generate a fluid capable of efficient fracture creation and excellent proppant transport. After fracturing, LPG may be recovered very rapidly, allowing savings on cleanup costs. In some embodiments, LPG may be predominantly propane, butane, or a mixture of propane and butane. In some embodiments, LPG may comprise more than 80%, 90%, or 95% propane, butane, or a mixture of propane and butane.
LPG fracturing processes may be implemented with design considerations to mitigate and eliminate the potential risks, such as by compliance with the Enform Document: Pumping of Flammable Fluids Industry Recommended Practice (IRP), Volume 8-2002, and NFPA 58 “Liquefied Petroleum Gas Code”.
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the features being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.