Patent Application
20140048253
Embodiments disclosed herein are related to maximizing power generation for apparatus which is transportable by road under transport weight restrictions for use at a site, and more particularly, for apparatus which is transported to a wellsite for use in oil and gas operations.
It is well known to transport a wide variety of apparatus, including but not limited to drilling equipment and service equipment, from wellsite to wellsite. Wellsite operations are characterized by equipment requiring significant power including in the thousands to tens of thousands of horsepower.
Engines used to power such apparatus are required to meet strict emission requirements. In many cases therefore, the conventional engines are high capacity so as to meet both the power demands and elevated temperature operational requirements to reduce emissions to meet the acceptable emission standards. As allowable emission levels become more restrictive, the engines are far hotter and the size of the engines and duty required typically increases resulting in an increase in the size of the cooling systems. Large cooling equipment, such as are on more radiators, is used to cool the engines. Diesel fueled engines, such as for driving generators require significant cooling.
Thus, as shown in
As a result, transport of the power units themselves may require the addition of one or more platforms or trailers over and above those used for the apparatus which utilize the unit's power. For large power requirements, power supply units and associated drive equipment are divided up into a plurality of parallel units. Thus, there is typically significant assembly required onsite once the various components have been transported.
There is a need in the industry for capable power plants which have a smaller footprint, lower weight and to facilitate road-transport within respective regulatory, such as DOT guidelines. Such units would be part of a system that requires a minimum number of personnel to operate and must be in compliance with transportation regulations in the greatest number of wellsites. More particularly, there is a need for apparatus which can be transported without excessive transport permitting.
In one particular context, the development of hydraulic fracturing in the oil and gas stimulation industry, over last 40 years, has resulted in ever increasing hydraulic horsepower (HP) requirements for hydraulic fracturing jobs. The power increase has been more than 100 times, increasing from 75 HP to over 10,000 HP. Similar oil and gas equipment requiring significant pumping horsepower includes cement pumps, nitrogen pumps, blenders, pressure trucks Carbon Dioxide pumps and propane pumps.
Often due to road transport limitations of the weight of roadable platforms, a plurality of units are provided that, in total, provide the necessary volumes of stimulation fluids and power required. Multiple units are associated with a variety of costs including repeated capital cost associated with each unit and personnel hired to deliver these plurality of units to a site.
As stated above, the current internal combustion power choices for coupling to fluid pumps are limited, either by their cost, such as in the case of expensive gas turbines, or by their overall equipment weight including the need for the large, heavy cooling equipment.
Herein, one or more design elements are combined to significantly increase the power plant capacity and minimize the number of platforms required for a given site process requirement. Generally, in embodiment disclosed herein, a power plant is provided for each unit that requires minimum or no supplemental cooling and is relieved of the usual excess weight associated therewith. Each power plant is readily sized for the process requirements and power demand without significant variation in neither space nor weight requirements.
In a broad aspect a transportable power platform for oil and gas wellsite usage comprises a transportable platform and one or more driven components of oil and gas equipment supported by the platform, each driven component has a power demand. In the oil and gas wellsite environment, the one or more driven components requires at least a base power demand of about 1500 HP or greater. To drive the components, a radial engine is also supported by the platform, the radial engine having normally air-cooled cylinders, and a power output matched to about the power demand of the one or more driven components. The radial engine is coupled thereto. Auxiliary support equipment is provided to service the one or more driven components and radial engine.
In another aspect, a system is provided for minimizing a number of transportable power platforms for providing process fluid to an oil and gas wellsite, comprising a plurality of transportable power units, each having a maximum payload weight, supporting a fluid pump having a power demand and having a power plant for providing a power output about that of the power demand. Each fluid pump comprises one or more driven fluid pumps and each power plant comprises a multi-row radial engine having a row multiplier to provide a power output to match the process power demand. A combined weight of auxiliary support equipment, one or more driven components and the multi-row engine is at about the maximum payload weight.
In another aspect, a process for maximizing the delivery of process fluid to an oil and gas wellsite, using a minimum number of transportable platforms supporting the fluid pumps thereon, comprises providing a plurality of transportable platforms, each having a maximum payload weight and supporting power unit thereon. Each power unit comprises a fluid pump having a power demand and a radial engine having at least one cylinder row for providing a power output about that of the power demand. The engine is configurable by configuring each radial engine for providing a base row of the at least one cylinder row and one or more supplemental rows according to a row multiplier established as a ratio of the power demand and the power output. When the row multiplier has a value of two or more, the radial engine is configured to have the base row and one or more supplemental rows respectively so as to match the power output to the power demand. One maximizes the power demand of the fluid pump and power output of the radial engine until a weight of the power unit is up to about the maximum payload weight.
FIGS. 2C1, 2C2 and 2C3 are side schematic illustrations of various transportable platforms for supporting the power and drive equipment units, namely self-propelled, trailer and trailered-skids respectively;
Large radial engines were eventually supplanted by jet engines, also lightweight, but at a much higher capital cost. An early patent illustration of a multi-row radial engine is as set forth in U.S. Pat. No. 2,787,994 to Brill (General Motors) in 1957. Historical records are populated with versions of multi-row engines.
No longer applied exclusively for aircraft, Applicant is also aware that a small, relatively lightweight, 1500 HP radially-configured, air cooled, reciprocating engine, used to power a one megawatt (1 MW) generator or genset, is available from CLEAR ENERGY™ Systems Inc. of Tempe, Ariz., USA. One such engine to Clear Energy is as illustrated in published US patent application US 2010/0072757 (A1) to Kelly et al, published Mar. 25, 2010. The Clear Energy radial engine is about one third the size and coupled with a generator is about one fifth the weight of a comparable diesel genset.
To date however, no radial engines have been employed as drivers for the oil and gas industry. Through the application of lightweight aircraft power plants to oil field and wellsite duties, Applicant has found that high power-requirement operations can now be accomplished by maximizing the usefulness and capability of mobile, transportable units while remaining within road transport weight regulations. The number of transportable units is minimized by maximizing each unit for maximum power output and cooling equipment if any, is minimized so to be contained on one roadable, transportable unit within weight allowances.
Applicant also understands radial engines to have a higher tolerance for impurities than a conventional diesel-fueled engine and are more flexible with respect to the type of fuel utilized. Thus, the radial engine can have a fuel source selected from natural gas (NG), which may be produced and compressed (CNG) on-site, and butane or propane, all of which are commonly available on-site at an oil or gas wellsite.
Further, unlike diesel engines, which require fuel to be recirculated from the engine to a recirculation tank, a radial engine fueled using CNG, propane or butane does not require any recirculation of fuel.
Accordingly, as shown in an embodiment of
Conveniently, one or more gensets, fit with radial engines, can also be fueled from the same fuel source as the radial engines 20 of the power units 18.
Turning to
A 1500 HP engine however does not generally provide sufficient output to drive larger on-site wellsite equipment such as large frac pumps, cement pumps, drilling equipment and the like. Typically, a large frac pump, requires an engine having an output of at least about 2500 HP. A frac pump of 2500 HP and corresponding prior art power plants, such as a diesel engine, happen to weigh about the maximum that can be transported on roadways under DOT requirements.
As shown in
As shown in
In other words, a comparable prior art power plant and driven components are about ⅕ the weight of conventional systems and enables larger power plants and driven components to be supported on conventional platforms in compliance with DOT weight requirements.
In particular, and as shown in Table 1, for a variety of common pump sizes, one or more rows 28 are configured to match the equipment power demand requirements. An engine has at least a base row 28b, and additional rows 28,28x,28x as necessary. Thus each engine has a base power output. Further, there is a row multiplier for determining the power output of a multi-row engine. The number of rows is configured where the power demand divided by the base power output yields the row multiplier. The row multiplier is an integer. One design approach is to round down the demand to output ratio so as to operate the driven components at a derated capacity for longer equipment life.
In determining the optimal unit 18, one starts with the transportable platform having a maximum payload weight. The one or more driven components have an equipment weight and the radial engine has an engine weight including a base engine weight, having at least the base row 28b, and a supplemental cylinder row weight for each additional row 28x,28x . . . and incremental or additional power associated therewith. The coupled, driven component and radial engine form a power unit 18 having a combined weight. The driven component 22 is selected for a process power demand, such as that necessary for the wellsite process, where multiple units are required to meet the process requirements, a fractional process power demand. The radial engine has a base power output for a single base row. Generally, each row adds a power increment about the same as that of the base power output. The number of rows for meeting the process power demand, including the base row, is equal to an integer value of the process ratio of the process power demand to base power output. Whether the integer value is rounded up or down is matter of operational preference. A rounding down of the multiplier derates the driven components and a rounding up ensues there is more power output available than power demand. The combined weight of all of the driven components 22, engine coupling components are less than or equal to the maximum payload weight.
In other words, one maximizes the power demand up to about the maximum payload weight and minimizes the transportable platforms. Each of a plurality of transportable platforms has a maximum payload weight and supports a power unit 18 thereon. Each power unit 18 comprises a driven component such as a fluid pump having a power demand. Each power unit 18 further comprises a radial engine having at least one cylinder row for providing a power output about that of the power demand. One configures each radial engine by providing a base row of the at least one cylinder row and one or more supplemental rows according to the row multiplier, the multiplier being established as a ratio of the power demand to the power output. The multiplier will have a practical maximum threshold ratio, such as where cooling or maintenance is adversely affected, thereafter additional units of engines and drive component being required. When the row multiplier has a value of two or more, the radial engine has the base row and is further fit with one or more supplemental rows respectively so as to match the power output to the power demand. The power demand of the fluid pump and power output of the radial engine are maximized until a weight of the power unit up to the maximum payload weight.
The weight Wu of a unit 18, being maximized to about maximum payload weight Wm is equal to the weight of the driven component We plus the weight of the engine We and the weight of each supplemental row Wr, if any, and the weight of the auxiliary equipment Waux including the gear box. The number supplemental rows depending on the number of rows Nrows determined suitable to meet the power demand, namely:
Wu=Wc+We+(Wr×Nrows)+Waux
The number of rows Nrows, including the base rows 28b and any supplemental rows 28x, is established from the ratio of the power demand of the driven component Pc divided by the power output of the engine with just the base row Peb. Therefore:
Nrows=Pc/Peb
Maximizing the power unit 18 involves increasing the power demand Pc and adding supplemental rows according to Nrows until Wu is about the maximum payload weight. If the number of rows Nrows exceeds the threshold ratio, then additional units 18 are required, each unit having unit weight Wu that is only a portion of maximum payload weight, the combined weight of the units no exceeding the maximum payload weight.
Applicant believes that all of the above can be placed on a transportable platform and remain within DOT weight limits. In wellsite operations that involve very large capacities, such as hydraulic fracturing, one can immediately reduce the number of required transportable platforms to one half, with the associated reduction in capital cost and personnel. With the ability to place large capacity equipment on trailers or skids, one can also move from integrated, self-powered platforms to trailered platforms. A shift to trailered platforms further reduces personnel cost as one can reduce the need for prior art staffing of one driver per platform to a small pool of drivers for shuttling multiple trailered platforms from wellsite to wellsite.
Simply, a transportable platform will have a Gross Vehicle Weight (GVW) that must comply with DOT requirements. The net payload comprises the combined weight of process equipment or driven components, the engine and auxiliary equipment for cooperative operation therebetween, and interfaces to the wellsite. A prior art payload of upwards of 30,000 pounds (for 2500 HP) can now be reduced to a payload more in the order of less than about 10,000 pounds yet providing a like power demand. One can see that the possible configurations for increased power demand and corresponding engines improves significantly. Indeed, the Clear Energy one-row, radial engine, fit to a 1 MW (nominal 1500 HP) generator is packaged in a trailer unit that is towable by a one ton pickup truck and weighs in the order of about 15,000 lbs, including the trailer.
Thus, for a given transportable platform, having a GVW, one can determine the maximum payload and maximize the driven component accordingly.
The weight of driven components is associated with certain auxiliary components such as piping for pumps, and a drive line between the engine and the driven components. The driveline may be as simple as a driveshaft and coupling or often includes gear boxes and structure to support same. The engine has little auxiliary equipment, and in the case of a radial engine having one or a few cylinder rows, the engine is air cooled, however as the cooling air flow through becomes impeded with additional cylinder rows, one can include supplemental liquid cooling or radiators.
Applicant has determined that for a given payload, such as an integrated transportable platform as shown in FIGS. 1 and 2C1, one can at least double the power output and corresponding driven components. Thus, conventional equipment at a power demand of 2,500 HP, driven with a, low emission, yet heavy, diesel engine, can be replaced with 5,000 HP driven component and a light, three-row, 4500 HP radial engine. The driven components, rated for 5,000 HP, can be driven at a derated 4,500 HP for extended life of the driven components. While the rated power demand can be matched closely with a corresponding engine, the increased power to weight ratio for the radial engine configurations enables one to over-design the driven components, which could otherwise be too heavy in the prior art scenarios. Operation of the driven components at derated power demand result in lower maintenance and longer operation between failures.
An example of a multi-row radial engine includes a Pratt & Whitney R-4360 Wasp Major that was a large 28-cylinder air-cooled, four-row by 7 cylinders per row, radial piston aircraft engine designed and built during World War II and having variations producing between about 2500 HP to nearly about 4000 HP.
As mentioned above, cooling of multi-row engines may not be as efficient using the air cooled system alone, as it is in the case for a single-row 1500 HP engine. Accordingly, each row 28 of multi-row radial engines, such as the R-4360 Wasp, are slightly rotationally offset or staggered each row aid in air-cooling of aft-rows aided by forced air in this case by propeller wash. Thus, one can supplement cooling with a relatively small, lightweight liquid circulation cooling system or radiator. Optionally, one need not stagger the rows and merely incorporate liquid cooling. As the engines can be both air and liquid cooled, any liquid cooling is a fraction of that used in comparable diesel power plants.
Where additional power is required, such as for apparatus exceeding about 5,000 HP and stacking of cylindrical rows beyond three (
As shown in
The number of engines 20 and cylinder rows 28 are configured so as to have an output matched to meet power demand for equipment 22. Where one radial engine 20 is insufficient for the process demand, engines having two or more cylinder rows 28b, 28x . . . can be provided and when multi-row engines reach a design limit, such as cooling or maintenance consideration, multiple engines 20, 20 can be provided such as in some parallel arrangement. One design scenario, as described earlier, is to provide an engine 20 at a power output less than that of the coupled driven components 22 for operating the equipment at a derated capacity for longer expected equipment life.
In wellsite operations that involve very large capacities, such as hydraulic fracturing, one can immediately reduce the number of required transportable platforms to at least one half, with the associated reduction in capital cost and personnel. With the ability to place large capacity equipment on trailers, one can also move from integrated, self-powered platforms to trailered platforms. A shift to trailered platforms further reduces personnel cost as one can reduce the need for prior art staffing of one driver per platform to a small pool of drivers for shuttling multiple trailered platforms from wellsite to wellsite.
In the context of the frac industry currently has an infrastructure comprising a plurality of trucks with pumps, such as quintuplex pumps and diesel engines mounted thereon as self-propelled frac units or a plurality of trailer units to which the pumps and diesel engines are mounted for transport using a fleet of trucks. On-site, the pumper trucks are parked adjacent the well or wells for positioning the pump for performing a fracturing operation. Using light-weight embodiments disclosed herein, the frac industry no longer has need for their own crew of drivers and transport infrastructure. Frac pumps having lightweight radial engines, as disclosed herein, are sufficiently light-weight that the units can be mounted on skids or on trailer units, which can be picked up and spotted at the wellsite, such as by a commercial transport company, as required.
In embodiments, as shown in
Further individual, one or more radial engine gensets 58, such as the 1 MW GENESIS 1000™, can be used to generate power for operating auxiliary apparatus on-site. Thus, a single fuel source is possible for all engines and power generation required at the site.
Embodiments disclosed herein provide a number of advantages:
This application claims the benefit of U.S. Provisional Patent application Ser. No. 61/683,426, filed Aug. 15, 2012, the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61683426 | Aug 2012 | US |
