Patent Application
20110048695
Embodiments of the invention relate to servicing multiple wells with a fluid and, more particularly, to manifolds and valving therein for selectively accessing the wells and further to minimize the erosive effects of stimulation fluids therein.
There are an increasing number of subterranean hydrocarbon reservoirs which are accessed using multiple wells for optimizing production therefrom. The wells and wellheads connected thereto are often closely spaced, the wellbores being angled downwardly and radially outwardly to access as much as the reservoir as possible.
Many or all of multiple pay zones in such reservoirs may be characterized by low permeability or other characteristics which require stimulation of one or more of the wells for increasing production therefrom. During selective stimulation of the wells, which may include fracturing operations performed on one well, wireline operations may be also be performed on other wells, such as to shift wellbore access from one zone to another zone. To consolidate pumping equipment, such as pumpers and proppant supply for use in fracturing, a large common manifold has been employed to connect a fracturing fluid inlet selectively to one or more of the wellheads of the multiple wells. Thus, multiple wells can be stimulated simultaneously with multiple trains of pumpers and manifolds.
Prior art manifolds are characterized by a plurality of adjacent flow blocks forming a single main manifold having a large bore for connecting fluid delivery lines to each wellhead. Large, full bore gate valves are located inline with the manifold bore between each adjacent flow block for isolating the adjacent flow blocks from one another. For example, for a manifold having a 7 inch bore, 7 inch valves, typically gate valves, are spaced inline between each adjacent flow block, fit flange to flange with ring seals and bolted together. Thus, when a valve or a seal is leaking, it is challenging and cumbersome to manipulate the single large manifold sufficiently to arrange to lift the compromised valve clear of the manifold. Further, it is difficult to part the flanges and remove, service and replace the compromised valve and ring seals without causing damage to the seals.
The need to maintenance the manifold and valves is exacerbated by the erosive nature of stimulation fluids flowing therethrough during stimulation operations. The stimulation fluids typically have high fluid flow rates caused to flow at high velocity from the single large bore manifold through like-sized outlets. The high velocity flow results in significant wear to the manifold and manifold valves, as well as to downstream equipment.
The addition of proppant, such as sand, to fracturing fluids is known to cause severe erosion. Generally, the proppant is added to the fracturing fluid at the pumpers and thus upstream equipment, such as the fluid pumpers, are also vulnerable to the erosive effects of the proppant-laden fracturing fluids passing therethrough.
Currently, it is known and common to stockpile replacement manifold components, including new flow blocks and valves, onsite and ready for replacement as the job proceeds. It is also known to have replacement fluid pumpers on standby to assume stimulation fluid delivery while active pumpers are taken offline for refurbishing. On large jobs, it is not uncommon to have ten or more pumpers on site, the redundancy required to maintain simultaneous and continuous stimulation despite the increased costs.
The flexibility of selection of wells which can be serviced by the prior art manifold is compromised by the valves located inline in the bore of the manifold. Wells can only be serviced in series. Once a gate valve has been closed in the bore to isolate a well, all of the wells fluidly connected to the manifold downstream of the closed gate valve are also isolated. Therefore should one wish to service wells which are remotely fluidly connected from one another it may not be possible to do so without delivering fluids to the intervening wells.
There is clearly a need in the industry for more cost effective and robust apparatus and methods for the delivery of stimulation fluids selectively to multiple wells and to improve the flexibility with which wells may be selected.
Embodiments of the present invention are directed to an apparatus, system and method of selectively servicing two or more wells concurrently. A fluid, such as a fracturing fluid is pumped from pumping units through a manifold that is fluidly connected to the two or more wells. The velocity of the fluid is reduced as the fluid travels from the pumping unit to the manifold and is further reduced as the fluid travels from the manifold to each of the two or more wells. The reduction of the velocity of the fluid reduces the erosive effects of the fluid on the manifold and other equipment, prolonging the operational life thereof.
In a broad aspect of the invention, a manifold for delivering a fluid for selectively servicing two or more wells has a manifold body having a live bore formed therethrough, the live bore having a live bore cross-sectional area. An inlet is fluidly connected to the live bore for receiving the fluid therein. Two or more distributors are also fluidly connected to the live bore for distributing the fluid to each of the two or more well. Each distributor has two or more outlets fluidly connected to one well of the two or more wells for delivery of fluids thereto, and each outlet has an outlet bore with an outlet cross-sectional area. Valves are positioned in each outlet bore of the two or more outlets for selectively isolating the fluid from one or more of the two or more wells. The total outlet cross-sectional area for each of the two or more distributors is greater than the live bore cross-sectional area for reducing the velocity of the fluid in the two or more outlets.
In another broad aspect of the invention, a system for servicing two or more wells accessing a formation, the wells having wellheads attached thereto, has a manifold, a source of a fluid, fluidly connected to the inlet; and fluid connections between the two or more outlets of each of the two or more distributions blocks and one wellhead of the two or more wells. The manifold can comprise a bore formed therethrough for receiving a fracturing fluid, an inlet fluidly connected to the bore for delivering the fracturing fluid to the bore, two or more outlets fluidly connected to the bore, at least one outlet fluidly connected to one of the two or more wells, and valves operatively connected between the manifold bore and each of the one or more wells for isolating the fracturing fluid from one or more of the two or more wells.
The system pumps the fluid from the fluid source to the manifold, the fluid flowing unimpeded through the main bore of the manifold block for delivery to the two or more outlets of each of the two or more distribution blocks.
When two or more valves of one or more of the two or more distribution blocks are actuated to an open position, the fluid flows through the main bore is delivered to the one or more wells fluidly connected thereto, and when the two or more valves of one or more of the two or more distribution blocks are actuated to a closed position, the one or more wells fluidly connected thereto are isolated from the fluid flowing through the main bore.
In another broad aspect of the invention, a method for replacing or repairing a valve in a manifold for selectively accessing two or more wells, the manifold having two or more distribution flow blocks, each distribution flow block fluidly connected to a main manifold bore and having two or more outlets fluidly connected to one well of the two or more wells for delivery of fluids thereto, each outlet having an outlet bore and a valve removeably secured thereto, involves discontinuing flow of fluid to the manifold bore, disconnecting the removeable connectors between the outlet and the valve, reconnecting a new or repaired valve to the outlet; and reestablishing the flow of fluid to the manifold bore.
As shown in
In the prior art, to lessen the fluid velocity and rate of erosion, the combined pumping capacity, typically from the plurality of pumpers 12, was routed through a plurality of parallel fluid supply lines 22 (four shown) to the manifold 10. The gate valves 18 dividing the manifold bore were then closed or opened selectively for isolating some wellheads 14 and for directing fluids to others. To lessen the fluid velocity and rate of erosion associated therewith, a plurality of parallel fluid delivery lines 24 (four shown) were connected from the outlets 20 to the wellhead 14. Applicant notes however that the parallel delivery lines 24 do not significantly reduce erosion that occurs at the connection of the large diameter outlets 20 to the large diameter manifold 10.
As shown in
An additional advantage of positioning the valves 208 in the outlets 206 is that there is greater flexibility in selecting wells 16 for servicing. As each well 16 is independently connected to the live bore 202 of the manifold 200, one or more wells 16 can be isolated from the manifold bore 202 and the fluids therein without affecting the delivery of fluid to any of the other wells 16.
Further, as each outlet 206 can have a cross-sectional area which is smaller than a cross-sectional area of the manifold bore 202, the valves 208 therein can also be reduced in size. Smaller valves are easier to remove for repair or replacement. Typically, the valves 208 are connected to the outlets 206 through removable connectors such as flanged connections 207.
When valves 208 require removal for replacement or repair, the flow of fluid to the live bore 202 is discontinued. The removable connections 207 between the outlet 208 and the valve 208 to be removed are disconnected and the valve 208 is removed. Thereafter, a new valve 208 or a repaired valve 208 is provided at the outlet 206 and the removable connectors 207 reconnected therebetween. Once the valve 208 has been replaced, the flow of fluids is reestablished through the live bore 202. Typically, the manifold 200 is pressure tested following replacement of the valve 208 to ensure the manifold 200 is capable of withstanding stimulation pressures.
While embodiments of the invention are suitable for delivery of a variety of stimulating fluids, embodiments of the invention are generally described herein in the context of a fracturing operation. Particular advantages are obtained when using embodiments of the invention for delivering fracturing fluids which comprise a particulate proppant P therein.
In greater detail, as shown in
In embodiments the flow blocks are connected using flanged connectors 230, each of the flanged connectors 230 having a bore 232 formed therethrough for forming the live bore 202.
Together, the receiving flow block 210, the distribution flow blocks 220, and the flanged connectors 230 structurally form the manifold body 201.
With reference to
The receiving bore 214 has an internal diameter RBID defining a total cross-sectional area RBXA. Each of the one or more inlets 212 has an internal diameter IID, defining an inlet cross-sectional area IXA. The total cross-sectional area of the longitudinal receiving bore RBXA is greater than the total combined inlet cross-sectional areas IXA for reducing the velocity of the fracturing fluid F entering the receiving bore 214.
With reference to
With reference to
The connector bore 232, the receiving bore 214 and the distribution bores 222, form the common, contiguous live bore 202 having a cross-sectional area LBXA.
In an embodiment, as shown in
As one of skill in the art will appreciate, the velocity of the fracturing fluid F, as it travels at an initial pumping velocity from the pumpers 12 through the inlets 212 to the larger cross-sectional receiving flow bore 214, is reduced. Thereafter as the fluid F travels from the distribution flow blocks 220 and to the total larger cross-sectional area of the outlets 206, the velocity is reduced again. The cumulative reduction in velocity of the fracturing fluid F minimizes the erosive effects of the abrasive fracturing fluid F on the manifold 200 and on other downstream well equipment.
For example, a typical 7 inch fracturing flow system, uses 7 inch inlet flow lines 212 to the inlet receiving block 210 having a total inlet cross-sectional area IXA, of about 39 square inches. Four—4 1/16 inch outlet lines 206 from the distribution flow block 220 have an outlet cross-sectional area OXA of about 13 square inches per outlet 2106, or a total outlet cross-sectional area OXA of about 52 square inches.
Applicant believes that the smaller valves 208, such as 4 inch valves, fit within the smaller, individual outlets 206 are more reliable than the large prior art valves. Embodiments of the invention permit use of the smaller, more reliable valves 208, yet permit a total outlet cross-sectional area OXA greater than that of the common contiguous live bore 202 permitting velocity reduction.
Table 1 summarizes typical velocity reductions observed according to embodiments of the invention.
As shown, the velocity of a fracturing fluid F entering a 7 1/16″ diameter live bore 202 of the manifold 200, through four 4 1/16″ inlet lines 212 at an initial pumping velocity of 16 cubic meters per minute (m3/min), is reduced from the initial pumping velocity to 34.4 feet per second (fps) in the live bore 202.
In a manifold 200 having fracturing fluid F flowing through the live bore 202 therein at 3 m3/min and four outlets 206 at each distribution block 220, each outlet 206 and valve 208 therein having a diameter of 3 1/16″, the velocity at each of the four outlets 206 is 34.4 fps.
In a manifold 200 having fracturing fluid F flowing through the live bore 202 therein at 4 m3/min and four outlets 206 at each distribution block 220, each outlet 206 and valve 208 therein having a diameter of 4 1/16″, the velocity at each of the four outlets 206 is 26 fps. If the outlet 206/valve 208 diameter is increased to 7 1/16″, the velocity is reduced to 8.6 fps.
In a manifold 200 having fracturing fluid F flowing through the live bore 202 therein at 5 m3/min and four outlets 206 at each distribution block 220, each outlet 206 and valve 208 therein having a diameter of 4 1/16″, the velocity at each of the four outlets 206 is 32.5 fps. If the outlet 206/valve 208 diameter is increased to 7 1/16″, the velocity is reduced to 10.8 fps.
Having reference to
As shown in
In embodiments, each of the main and slave manifolds 200m, 200s can be shorter in length, the overall manifold system being capable of servicing the same number of wells 16 as would be serviced using a single, large manifold 200. Advantageously, the shorter length manifolds 200m, 200s are particularly suited to sites where space constraints are an issue.
Having reference again to
Having reference to
In embodiments of the invention, issues related to the erosive nature of the proppant P present in stimulation fluids, such as fracturing fluids F, are minimized using systems and methodology for delivery thereof. As one of skill in the art will appreciate, while embodiments of the invention are described herein using a manifold 200 according to an embodiment of the invention to achieve the combined benefits thereof, the systems and methods described can also be practiced using prior art manifolds 10.
Utilizing systems and methods according to embodiments of the invention, proppant P can be delivered directly to the wellheads 14 for mixing with fluid F at the wellheads 14, can be delivered to the pumpers 12 for forming the fracturing fluid F therein for delivery to a manifold 10, 200 for subsequent delivery to the wellheads 14 or can be delivered to both the manifold 200 and the wellheads 14 for mixing at the wellheads 14.
In the case where proppant P is delivered to the pumpers 12 for delivery to the manifold 200, the fracturing fluid F is delivered as described for the prior art as shown in
As shown in
Embodiments which deliver proppant slurry PS directly to the wellheads 14 eliminate any erosion in pumpers 12, in the manifold 200 and in the valves 108 in the manifold outlets 206. The proppant pumpers 12 however are placed at higher risk for erosion of pumping equipment therein.
In an embodiment of the invention, proppant P is provided to both the fluid pumpers 12 and to the proppant pumpers 12p. In this embodiment, proppant P is provided to the fluid pumpers 12 at a first concentration PS1 and is provided to the proppant pumpers 12p at a second concentration PS2 which is higher than the first concentration. The fracturing fluid F with proppant P and the proppant slurry PS are mixed at the wellheads 14 to a final concentration or design load of proppant P for delivery to the wells 16.
In embodiments, the first proppant concentration PS1 is lower than concentrations which result in significant erosion and thus, the fluid pumpers 12 can last much longer before servicing, unlike in the prior art where servicing is typically performed periodically during well stimulation.
Further, as the fracturing fluid F flowing through the manifold 200 and downstream components is less erosive, the rate of flow can be increased without increased erosion. With increased flow rates, the number of flow lines required to deliver the same volume of fracturing fluid F can be decreased.
Accordingly, embodiments which utilize only two fluid delivery lines 22 to the wellheads 14 utilize only two outlet ports 206 and two valves 208 in each distribution flow block 220. The remaining outlets 206 remain unused and can be fit with valves 208 which are closed to isolate the outlets 206 or alternatively the outlets 206 can be plugged. Alternatively, the distributions blocks 220 can be manufactured having fewer outlets 206 for this purpose. The reduction of flow lines 22,24 required to conduct fracturing fluid from the pumping units 12 to the well 16 contribute to reducing capital expense, faster setup, faster pressure testing, due in part to fewer components and connections, and a reduction in equipment clutter onsite.
As shown in
Where the proppant slurry PS is provided to the wellhead 14 from the proppant pumpers 12p through delivery line 28, either at the full design concentration or at the second concentration PS2, the proppant slurry PS from the proppant pumpers 12p is added to a port 34 of the fracturing head 30 to combine with the fracturing fluid F injected therein through the opposing inlets 32. The net result is that the design load of proppant P is provided in the overall combined fluid flow downhole.
For example, two 4-inch fluid delivery lines 24 from the manifold 200 coupled to opposing inlets 32 at the fracturing head 30 can deliver the fracturing fluid F from the manifold 200 at a flow rate of about 7 m3/min. Proppant slurry PS, at concentrations of up to 800 kg/m3, pumped from the proppant pumpers 12p through a single 3-inch delivery line 28 connected to the port 34 of the fracturing head 30, delivers the proppant slurry PS at a flow rate of about 3 m3/min, which is substantially less than the flow rate of the fracturing fluid F. In embodiments, the port 34, is inline with a bore of the fracturing head 30 and thus minimizes even further any erosive effects at the fracturing head 30.
Applicant is aware that the concentration of proppant PS2 in the proppant slurry PS might be four times the concentration of proppant PS1 in the fracturing fluid F and yet remain pumpable. Where the proppant pumpers 12p pump proppant slurry PS having a high concentration of proppant P, the velocity is reduced. Further, as the high concentration proppant slurry PS contains very low fluid levels, it is not responsible for providing operational levels of fracturing fluid F. Thus, it becomes feasible to expend energy to warm up the smaller amounts of ambient water used to prepare the proppant slurry PS to enhance chemical mixing during the preparation of the proppant slurry PS at the blender 26.
| Number | Date | Country | |
|---|---|---|---|
| 61257838 | Nov 2009 | US | |
| 61258555 | Nov 2009 | US |
