GB2605840A

GB2605840A - System for varying flow of fluid in well stimulation arrangement

Info

Publication number: GB2605840A
Application number: GB2105452.3A
Authority: GB
Inventors: Dwain Converse Perry; Alan Otten Casey; Cody Bufkin Joseph
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2021-04-16
Filing date: 2021-04-16
Publication date: 2022-10-19
Also published as: GB202105452D0

Abstract

A system 110 for varying flow of a fluid in a well stimulation includes a vessel 114. The system also includes one or more pumps 104 fluidly coupled with the vessel. The pumps are controllable to direct the fluid towards a well head 102 at a desired flow rate and a desired fluid ramp rate. The system further includes a controller to receives an input signal corresponding to at least one of a first pressure measured at the well head, a second pressure measured at an exit of the pumps, an exit flow rate at the exit of the pumps, a fluid level in the vessel, and a health of the pumps. The controller controls the one or more pumps for varying at least one of an actual flow rate of the fluid and an actual fluid ramp rate of the fluid based on receipt of the input signal.

Description

SYSTEM FOR VARYING FLOW OF FLUID IN WELL STIMULATION

ARRANGEMENT

Technical Field

100011 The present disclosure relates to a system for varying flow of a fluid in a well stimulation arrangement.

Background

[0002] A variety of operations, such as drilling, cementing, acidizing, water jet cutting, hydraulic fracturing, and the like, can be performed at a well site, as per requirements. Hydraulic fracturing, or "fracking", is used for extracting oil and gas from geologic formations, such as shale, using horizontal fluidized drilling. The hydraulic fracturing operation may involve usage of multiple pumps for directing a pressurized fluid towards a well head. More particularly, several pumps may be fluidly connected to the well head via fluid conduits and/or a manifold. Further, a blender assembly may be in fluid communication with the pumps for directing fluid towards the pumps.

[0003] However, during hydraulic fracturing operations, situations such as high formation pressure response, sanding off a well, addition of excessive diverter, incorrect friction reducer formula or concentration, low tub levels associated with the blender assembly, and the like, may lead to failure of one or more equipment at the well site, such as the pumps. Such equipment failure may increase system downtown, thereby affecting productivity at the well site. Further, damage to the one or more equipment may compromise with safety of a personnel at the worksite. [0004] WO Patent Application Number 2020/097060 describes a system including a number of processors, a memory, a data interface that receives data, a control interface that transmits control signals to control a number of pumps of a hydraulic fracturing operation, and a number of components that include a number of modeling component that predicts pressure in a well. The well is fluidly coupled to the pumps. The components include a pumping rate adjustment component that generates a pumping rate control signal for transmission via the control interface, a capacity component that estimates a real-time pumping capacity for each individual pump, and a control component To achieve a target pumping rate for the pumps during the hydraulic fracturing operation, the control component generates an engine throttle and a transmission gear setting for each of the individual pumps using an estimated real-time pumping capacity for each individual pump via the control interface

Summary of the Disclosure

[0005] In one aspect of the present disclosure, a system for varying flow of a fluid in a well stimulation arrangement is provided. The system includes a vessel for holding the fluid therein. The system also includes one or more pumps fluidly coupled with the vessel. The one or more pumps pressurize the fluid received from the vessel. The one or more pumps are controllable to direct the fluid towards a well head at a desired flow rate and a desired fluid ramp rate. The system further includes a controller communicably coupled with the one or more pumps. The controller receives an input signal corresponding to at least one operating parameter of the well stimulation arrangement. The at least one operating parameter includes one of a first pressure measured at the well head, a second pressure measured at an exit of the one or more pumps, an exit flow rate at the exit of the one or more pumps, a fluid level in the vessel, and a health of the one or more pumps. The controller controls the one or more pumps for varying at least one of an actual flow rate of the fluid and an actual fluid ramp rate of the fluid based on receipt of the input signal.

[0006] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

[0007] FIG. I is a schematic illustration of a well stimulation arrangement, according to examples of the present disclosure; [0008] FIG. 2 illustrates a block diagram of a system for varying flow of a fluid in the well stimulation arrangement of FIG. 1, according to examples of the present disclosure; 100091 FIG. 3 illustrates an exemplary plot representing fluid flow and pressure for the well stimulation arrangement, according to examples of the present disclosure arrangement; [0010] FIG. 4 is an exemplary illustration of a number of zones for varying an actual flow rate of the fluid and/or an actual fluid ramp rate of the fluid for different pressure inputs, according to examples of the present disclosure; and [0011] FIG. 5 is an exemplary illustration of a number of zones for varying the actual flow rate and/or the actual fluid ramp rate for different fluid levels in a vessel, according to examples of the present disclosure.

Detailed Description

[0012] Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.

[0013] FIG. 1 is a schematic illustration of a well stimulation arrangement 100, in accordance with examples of the disclosure. The well stimulation arrangement 100 may be deployed at a well site for performing one or more oilfield operations. In an example, the well stimulation arrangement 100 may be used for performing a hydraulic fracturing operation or fracking in one or more well heads 102. In operations, such as hydraulic fracturing or fracking, an inner core of the well heads 102 is fractured using a pressurized fluid. The hydraulic fracturing involves injection of the fluid into the well heads 102. The fluid is injected into the well head 102 to create a number of cracks in the inner core of the well head 102 through which natural gas, petroleum, and brine can flow freely. The natural gas, petroleum, and brine may be collected once the pressurized fluid is removed from the well head 102. After removal of the fluid, small grains of the fluid such as sand, aluminum oxide, and the like, may hold the fractures open.

[0014] The well stimulation arrangement 100 typically includes one or more trailers 106. In the illustrated example, the well stimulation arrangement 100 includes twenty trailers 106. However, a total number of the trailers 106 may vary, as per application requirements. Each trailer 106 includes a power source (not shown). The power source associated with the trailers 106 may be of any suitable type, size, power output, age, etc. The power source provides power to pressurize the fluid that is injected into the well head 102 from the trailer 106. In other words, the power source may cooperate with a transmission (not shown) and a pump 104 of the corresponding trailer 106 to pressurize and inject the fluid for hydraulic fracturing operations at the well site.

10015] In one example, the power source may include an engine. The engine may include an internal combustion engine that uses diesel as fuel. In some examples, the engine may operate using other fuels such as gasoline, liquified petroleum gas (LPG), liquified natural gas (LNG), compressed natural gas (CNG), kerosene, and the like. It should be noted that the type of fuel used in the engine does not limit the scope of the present disclosure. In another example, the power source may include an electric pump. In an example, the electric pump may be disposed on the trailer 106, instead of or in addition to the engine. In some examples, the electric pump may be powered using a bank of batteries, a generator, and the like, to drive the pump 104 via the transmission. In some examples, the power source may include a motor and a Variable Frequency Drive (VFD) that operates based on receipt of power from an external electric power source.

[0016] Further, each trailer 106 includes the transmission and one or more pumps 104 loaded on the trailer 106. The trailer 106 further includes a frame (not shown) and wheels (not shown). The wheels allow the trailer 106 to be mobile and be hauled, such as by attachment to the trailer 106, to different well sites or within a well site. There may be multiple trailers 106 at the well site to inject the fluid into different well heads 102 and, often times, the trailers 106 may have different types of power sources, transmissions, and/or pumps 104 loaded thereon.

[0017] Further, in an example, the power source is mechanically coupled to the transmission using any type of drive train components such as a drive shaft, a clutch configuration, a continuous variable transmission (CVT), and the like. In other examples, the converted power can be controlled through the VFD or any motor governing device. It should be noted that the type of mechanical coupling does not limit the scope of the present disclosure. In other arrangements, the pumps 104 may be directly mounted to a skid or any other suitable frame or platform for long term operations. In some examples, the pumps 104 may be independent units that are plumbed to a manifold. In other examples, after the completion the fracturing operation at one well site, the pumps 104 may be disconnected from the manifold and may be connected to the manifold at a new well site.

100181 In some examples, the pump 104 may include a power end connected to the power source and a fluid end that moves the fluid to be pressurized from a low-pressure side to a high-pressure side. The fluid from the high-pressure side is then directed towards the well head 102. Further, the pumps 104 may include a prime mover (not shown) that drives a crankshaft (not shown) through a transmission (not shown) and a drive shaft (not shown). It should be noted that the trailer 106 may include many other components that assist in the hydraulic fracturing operations, without any limitations.

100191 In the illustrated example, the fluid is a mixture of water, chemicals such as the gelling agent, and sand. For example, the fluid can be a slurry. The well stimulation arrangement 100 includes a system 110 for varying flow of the fluid in the well stimulation arrangement 100. The system 110 includes a blender assembly 112. Further, the system 110 includes a vessel 114 for holding the fluid therein. The vessel 114 is associated with the blender assembly 112. The vessel 114 is embodied as a container or tub for holding and mixing the fluid for formation of a homogenous mixture. The blender assembly 112 may further include mixing elements (not shown) associated therewith for homogenous mixing/blending.

100201 The system 110 also includes a number of water tanks 116 to store water. In other examples, the system 110 may eliminate the water tanks 116 and the water can be pumped directly towards the vessel 114 from a remote reservoir via fluid conduits. The water tanks 116 are fluidly coupled to the vessel N. The system 110 further includes a chemical reservoir 118 fluidly coupled to the vessel 114. The chemical reservoir 118 may hold the gelling agent. The system 110 includes a sand feeder 120 to feed the sand in the vessel 114. The water tanks 116 feed water to the to the vessel 114. Further, the chemicals from the chemical reservoir 118 are also directed towards the vessel 114. Specifically, the sand, the chemicals, the water, and the gelling agent are directed towards the blender assembly 112 where they are blended/combined to form the fluid having a gel like consistency.

[0021] Further, the vessel 114 includes a first sensor 122 (shown in FIG. 2).

The first sensor 122 may be associated with the vessel 114. The first sensor 122 may be used to determine properties of the fluid in the vessel 114. In an example, the first sensor 122 includes a level sensor that measures a fluid level "Li" of the fluid in the vessel 114. In another example, the first sensor 122 may embody a densometer for measuring density of the fluid in the vessel 114.

[0022] The system 110 further includes the one or more pumps 104 fluidly coupled with the vessel 114. The one or more pumps 104 pressurize the fluid received from the vessel 114. The one or more pumps 104 are controllable to direct the fluid towards the well head 102 at a desired flow rate "DF" and a desired fluid ramp rate "DR". The term "desired flow rate" as used herein may indicate a desired value of the flow rate of the fluid based on current operating parameters at the well site. Further, the term "desired fluid ramp rate" as used herein may indicate a desired value of the fluid ramp rate of the fluid based on current operating parameters at the well site. The term "ramp rate" as used herein may be indicative of a rate of change in fluid flow. It should be noted that the ramp rate may vary depending on whether the flow rate is increasing or decreasing. It should be noted that the desired flow rate "DF" and the desired fluid ramp rate "DR" may vary at different instances of time based on various factors, such as the fluid level "Li" in the vessel 114, pressure at different locations of the well stimulation arrangement 100, and the like, without any limitations.

[0023] The pumps 104 are fluidly coupled to the vessel 114 using first conduits (not shown). The first conduits distribute the fluid from the vessel 114 to the pumps 104. The first conduits may include pipes, such as concrete or steel pipes. Further, the first conduits may form a part of an inlet manifold system that directs the fluid from the vessel 114 to the pumps 104. The first conduits may include a number of valves (not shown) that connect the vessel 114 with the pumps 104.

100241 Each of the pumps 104 receive the fluid at a low pressure and discharge it to a number of second conduits at a higher pressure. The second conduits 126 distribute the fluid from the pumps 104 towards the well head 102. The second conduits 126 may include pipes, such as concrete or steel pipes. Further, the second conduits 126 may form a part of an outlet manifold system that directs the fluid from the pumps 104 to the well heads 102. The second conduits 126 may include a second sensor 128. The second sensor 128 may measure a first pressure "Pl" that corresponds to a pressure at the well head 102. The second sensor 128 may be disposed such that the second sensor 128 is proximate to the well head 102 for measuring the first pressure "Pl".

100251 In the illustrated example, the pumps 104 are mounted on the trailer 106 for ease of transportation. Further, the pumps 104 include a number of sensors associated therewith. For example, the pump 104 may include a third sensor 130 (shown in FIG. 2) that measures a second pressure "P2" of the fluid at an exit of the corresponding pump 104, a fourth sensor 132 (shown in FIG. 2) that measures a speed of the corresponding pump 104, and the like.

100261 Further, the inputs from the fourth sensor 132 in addition to parameters such as volume and geometry of the pump 104 may be used to determine an exit flow rate "Fl" at the exit of the pumps 104. In some examples, the system 110 may include a flow rate sensor (not shown) disposed at the exit of the corresponding pump 104 for determining the exit flow rate "F1-. Further, the system 110 may include a pump health monitoring module 124. The pump health monitoring module 124 may include various sensors associated with the pumps 104 that assist in determination of a health of the pumps 104.

[0027] Referring to FIG. 2, the system 110 includes a controller 134 communicably coupled with the one or more pumps 104. In an example, the system 110 may include a single controller 134 that is communicably coupled with each pump 104. In other examples, the system 110 may include multiple controllers 134 such that each controller 134 is positioned on a corresponding trailer 106 (see FIG. 1). In some examples, the system 110 may include a central controller that communicates with the controller 134 on the corresponding trailer 106 for controlling the pump 104. Further, the controller 134 on the trailer 106 may communicate with a pump controller (not shown) that is associated with the corresponding pump 104 for controlling the pump 104. In some examples, the controller 134 may control the inlet of the pumps 104. For example, the controller 134 may be designed to control the valves of the first conduits associated with the corresponding pump 104. In other examples, the controller 134 may control a speed of a motor (not shown) associated with the corresponding pump 104 to control the speed of the pump 104. It should be noted that the controller 134 may be coupled to any portion of the pumps 104 that allows control of the corresponding pump 104 for varying the flow of the fluid, without any limitations.

100281 Further, the first sensor 122, the second sensor 128, the third sensor 130, and the fourth sensor 132 are communicably coupled to the controller 134. Moreover, the controller 134 is communicably coupled to the pump health monitoring module 124. The first sensor 122, the second sensor 128, the third sensor 130, the fourth sensor 132, and the pump health monitoring module 124 transmit a number of input signals corresponding to one or more operating parameters of the well stimulation arrangement 100 to the controller 134. The controller 134 receives the input signal corresponding to the one or more operating parameters of the well stimulation arrangement 100. The one or more operating parameters may include the first pressure "Pl" measured at the well head 102, the second pressure "P2" measured at the exit of the one or more pumps 104, the exit flow rate "Fl" at the exit of the one or more pumps 104, the fluid level "Ll" in the vessel 114, and the health of the one or more pumps 104. In some examples, the one or more operating parameters may also include a desired formation pressure at the well head 102.

100291 Further, the controller 134 receives the input signals on a real time basis. If the controller 134 detects that the input signals for any operating parameter does not fall in a predefined range or an optimal operating range, the controller 134 operates to control an actual flow rate "AF" or an actual fluid ramp rate "AR" in order to prevent equipment damage. More particularly, the controller 134 controls the one or more pumps 104 for varying the actual flow rate "AF" of the fluid and/or the actual fluid ramp rate "AR" of the fluid based on receipt of the input signal. Varying the actual flow rate "AF" of the fluid and the actual fluid ramp rate "AR" of the fluid in the predefined range based on the controlling of the pumps 104 may prevent failure of the equipment.

[0030] As discussed above, the controller 134 varies the actual flow rate "AF" and the actual fluid ramp rate "AR' based on a variety of factors, such as the first pressure "Pl", the second pressure "P2", the exit flow rate "Fl", the fluid level" Li", and the health of the one or more pumps 104. The control of the actual flow rate "AF" and the actual fluid ramp rate "AR" based on the input signals corresponding to the various factors listed above will now be explained in detail.

[0031] Referring to FIG. 3, an exemplary plot 136 illustrating the actual flow rate "AF" of the fluid and the pressure of the fluid with respect to time for the well stimulation arrangement 100 is illustrated. A first curve 138 is representative of the actual flow rate "AF" and a second curve 140 is representative of the pressure. In this example, the pressure is the well head pressure that is referred to as the first pressure "Pl" herein. Alternatively, the pressure may include the second pressure "P2" measured at the exit of the pumps 104. Further, a line 141 is representative of a first setpoint such that if the first pressure "Pl" or the second pressure -P2" is greater than the first setpoint than there may be a possibility of equipment damage. The first setpoint is embodied as a pressure threshold setpoint herein The first setpoint can be decided and varied, as per application requirements.

[0032] Referring to FIG. 4, a first response strategy for varying the actual flow rate "AF" and the actual fluid ramp rate will now be explained in detail. The first response strategy includes varying the actual flow rate -AF" and the actual fluid ramp rate "AR' based on the first and/or second pressures "131", "P2". In an example, the pressure may be the first pressure "P 1" i.e., the well head pressure. In another example, the second pressure "P2" measured at the exit of the one or more pumps 104 may be used to vary the actual flow rate "AF" and the actual fluid ramp rate "AR". Further, in some examples, the variation in the actual flow rate "AF" and the actual fluid ramp rate "AR" may also be dependent on an amount of -1 0-friction reducer present in the fluid and the desired formation pressure at the well head 102.

100331 For exemplary purposes, the first response strategy will now be explained based on usage of a pressure input "P" for varying the actual flow rate "AF" and the actual fluid ramp rate "AR". The pressure input -P" may be indicative of either the first pressure "Pl" or the second pressure "Pr, without any limitations. In some examples, the first response strategy may also consider a pressure ramp rate while determining the pressure input "Fr. It should be noted that the actual flow rate "AF" and the actual fluid ramp rate "AR-may be varied based on the first setpoint, and specifically, a difference between the pressure input "P" and the first setpoint. In some examples, the actual flow rate -AF" and the actual fluid ramp rate "AR" may be varied based on equipment pressure setpoint instead of the first setpoint.

100341 In other examples, the exit flow rate "Fl" at the exit of the one or more pumps 104 may be used as the input to vary the actual flow rate "AF" and the actual fluid ramp rate "AR". In such an example, the actual flow rate "AF" and the actual fluid ramp rate "AR" may be varied based on a threshold flow rate setpoint [00351 In the first response strategy, the controller 134 defines five zones 142, 144, 146, 148, 150 that are configurable based on the pressure input "P". The five zones 142, 144, 146, 148, 150 include the first zone 142, the second zone 144, the third zone 146, the fourth zone 148, and the fifth zone 150. The zones 142, 144, 146, 148, 150 are configurable in terms of percentages from the first setpoint. Furthermore, in the first response strategy, the pressure input "P", the actual flow rate "AF", and the actual fluid ramp rate "AR" are determined for a linear control of the actual flow rate "AF"/actual fluid ramp rate "AR" or an exponential control of the actual flow rate "AV/actual fluid ramp rate "AR".

100361 In the first zone 142, when the pressure input "P" increases, such that the pressure input "F." approaches the first setpoint, the actual fluid ramp rate "AR" is reduced linearly. In an example, the actual fluid ramp rate "AR-may be reduced by half of a first ramp rate "RI'. The first ramp rate "Rl" may be defined as a site ramp rate which may be configured and varied, as per application requirements The first ramp rate "RI" may be defined in terms of Barrels Per Minute/ Second (BPN4/S). Alternatively, the actual fluid ramp rate "AR" may be reduced by 25%, 75%, and the like.

10037] In the second zone 144, if the pressure input "P" keeps increasing, the actual fluid ramp rate "AR-is reduced exponentially based on a first ramp rate factor "RF1". It should be noted that the reduction in the actual fluid ramp rate "AR" is performed based on multiplication of the first ramp rate factor "RF1" and the first ramp rate -RI". The first ramp rate factor "RF1" is a fluid ramp rate reduction percentage factor as per table 1 given below.

Table 1

Pressure input First ramp rate factor Al Bl% Customer Acceleration Limit A2 B2% Customer Acceleration Limit A3 B3% Customer Deceleration Rate A4 Maximum Deceleration Rate 10038] Table 1 contains various values of different pressure inputs "P" and corresponding values of the first ramp rate factor "RF For example, when the pressure input "P" is "Al", the first ramp rate factor "RF1" may be "Bl-%, and so on. The pressure input "P" is defined in terms of Pound-Force Per Square Inch/Second (PSI/S). Further, when the pressure input "13-lies in the third zone 146, the actual fluid ramp rate "AR" is set to zero. Specifically, when the pressure input "P" lies in the third zone 146, the controller 134 does not perform any action, i.e., the actual flow rate "AF" and/or the actual fluid ramp rate "AR" is not increased or reduced.

[0039] Moreover, when the pressure input "P" lies in the fourth zone 148, the actual flow rate "AF' is linearly reduced based on reduction in the actual fluid ramp rate "AR" by a first configurable percentage factor "FC1". The actual flow rate "AF"' is reduced such that the actual flow rate "AU"' is equal to a first flow rate "F2" The first flow rate -F2" mentioned herein may be defined as an optimum global minimum flow rate at which the fluid can flow towards the well head 102. The first flow rate "F2" may be defined in terms of Barrels Per Minute (BPNI). It should be noted that the reduction in the actual fluid ramp rate "AR" is performed based on multiplication of the first configurable percentage factor "FC1" and the first ramp rate "RI" and making the actual fluid ramp rate "AR" negative.

[0040] Further, when the pressure input "P" lies in the fifth zone 150, the actual flow rate "AF" is reduced exponentially by a maximum deceleration factor or based on a second ramp rate factor "RF2-. The second ramp rate factor "RF2" is a fluid ramp rate reduction percentage factor as per table 2 given below.

Table 2

Pressure inputs Second ramp rate factor X1 Yl% X2 Y2% X3 Y3% X4 Y4% [0041] Table 2 contains various values of different pressure inputs "P" and values of the second ramp rate factor "RF2" based on the values of the pressure inputs "P". For example, when the pressure input "P" is "X 1 ", the second ramp rate factor "RF2" may be "Yl" %, and so on.

[0042] Further, when the pressure input 13" starts decreasing and the pressure input -P" is in the fifth zone 150, the same technique that is used for the increase in the pressure input "P" in the fifth zone 150 is applied for controlling the actual flow rate "AF" as discussed above. As the pressure input "P" starts decreasing, and the pressure input "P" is in the fourth zone 148, the actual flow rate "AF" may be maintained at the first flow rate "Fr by applying the same technique that is used for the increase in the pressure input "P-in the fourth zone 148.

100431 Moreover, as the pressure input "P" keeps decreasing such that the pressure input "P" lies in the third zone 146, no action is taken by the controller 134 and the actual fluid ramp rate "AR" is set to zero. When the pressure input "P" is in the second zone 144, the actual fluid ramp rate "AR" is increased in an exponential manner. More particularly, in the second zone 144, the actual fluid ramp rate "AR" is increased exponentially based on the first ramp rate factor "RF1" as per Table 1. It should be noted that the increase in the actual fluid ramp rate "AR" is performed based on multiplication of the first ramp rate factor 'RF1" and the first ramp rate "Rl". Further, when the pressure input "P" decreases further such that the pressure input "P-is in the first zone 142, the actual fluid ramp rate "AR" is increased linearly. In an example, the actual fluid ramp rate "AR" may be increased by double of the first ramp rate "RI" in the second zone 144. Alternatively, the actual fluid ramp rate -AFC may be increased by 25%, 50%, 75%, and the like.

100441 Referring to FIG. 5, a second response strategy for varying the actual flow rate "AF" of the fluid and the actual fluid ramp rate "AR" of the fluid will now be explained in detail. The second response strategy includes varying the actual flow rate "AF" and the actual fluid ramp rate "AR" based on the fluid level "LI" in the vessel 114. In the second response strategy, the controller 134 may use the inputs from the third sensor 130 or the fourth sensor 132 for varying the actual flow rate -AF" and the actual fluid ramp rate "AR-. Further, in some examples, the variation in the actual flow rate "AF" and the actual fluid ramp rate "AR" may also be dependent on the amount of friction reducer present in the fluid.

100451 The second response strategy includes varying the actual flow rate "AF" and the actual fluid ramp rate "AR" based on a second setpoint, and specifically, a difference between the fluid level "L 1" and the second setpoint. The second setpoint is a configurable fluid level percentage setpoint and is represented by a line 162 herein. In the second response strategy, the controller 134 defines five zones 152, 154, 156, 158, 160 that are configurable based on the fluid level "Li" in the vessel 114. The five zones 152, 154, 156, 158, 160 include the first zone 152, the second zone 154, the third zone 156, the fourth zone 158, and the fifth zone 160.

100461 In the first zone 152, as the fluid level "Ll decreases, such that the fluid level "Li" approaches the second setpoint, the actual fluid ramp rate "AR" is reduced linearly. In an example, the actual fluid ramp rate "AR" may be reduced by half of the first ramp rate "Rl". Alternatively, the actual fluid ramp rate -AR" may be reduced by 25%, 75%, and the like.

[0047] In the second zone 154, if the fluid level "Li" keeps decreasing, the actual fluid ramp rate "AR" is reduced exponentially based on a third ramp rate factor "RF3". The third ramp rate factor "RF3" may be considered based on the current fluid level -L1". It should be noted that the reduction in the actual fluid ramp rate "AR" is performed based on multiplication of the third ramp rate factor "RF3" and the first ramp rate "RI". The third ramp rate factor "RF3" may include a fluid ramp rate reduction percentage factor that may be configured based on different fluid levels -L1". The third ramp rate factor "RF3" may be similar to the first ramp rate factor "RF1" as shown in Table I. [0048] Further, when the fluid level "Li" lies in the third zone 156, the actual fluid ramp rate "AR" is set to zero. Specifically, when the fluid level "L 1" lies in the third zone 156, the controller 134 does not perform any action, i.e., the actual flow rate "AU"' and/or the actual fluid ramp rate "AR" are not increased or reduced. Moreover, when the fluid level "Li" lies in the fourth zone 158, the actual flow rate "AF" is linearly reduced based on reduction in the actual fluid ramp rate "AR" by a second configurable percentage factor -FC2". The actual flow rate -AF" may be reduced such that the actual flow rate "AF" is equal to the first flow rate "F2". It should be noted that the reduction in the actual fluid ramp rate "AR" is performed based on multiplication of the second configurable percentage factor "FC2' and the first ramp rate "RI" and making the actual fluid ramp rate "AR" negative.

[0049] Further, when the fluid level "Li" decreases and the fluid level "Li" lies in the fifth zone 160, the actual flow rate "AF" is reduced exponentially by a maximum deceleration factor or based on a fourth ramp rate factor "RF4". The fourth ramp rate factor "RF4" may be considered based on the current fluid level "LI". It should be noted that the reduction in the actual fluid ramp rate "AR-is performed based on multiplication of the fourth ramp rate factor "RF4" and the first ramp rate "RI". The fourth ramp rate factor "RF4" may include a fluid ramp rate reduction percentage factor that may be configured based on different fluid levels "Li". The fourth ramp rate factor "RF4" may be similar to the second ramp rate factor "RF2" as shown in Table 2.

[0050] Further, when the fluid level "Li" starts increasing and the fluid level "LI" is in the fifth zone 160, the same technique that is used for the decrease in the fluid level "Li" in the fifth zone 160 is applied for controlling the actual flow rate as discussed above. Further, when the fluid level "Li" starts increasing based on filling of the vessel 114 and the fluid level "Li" lies in the fourth zone 158, the actual flow rate "AF" may be maintained at the first flow rate "F2" by applying the same technique that is used for the decrease in the fluid level "LI" in the fourth zone 148. Moreover, as the fluid level "LI" keeps increasing such that the fluid level "Li" lies in the third zone 156, no action is taken by the controller 134 and the actual fluid ramp rate "AR" is set to zero.

100511 When the fluid level "LI" is in the second zone 154, the actual fluid ramp rate "AR" is increased in an exponential manner. More particularly, in the second zone 154, the actual fluid ramp rate "AR" is increased exponentially based on the third ramp rate factor "RF3". The third ramp rate factor "RF3" may be considered based on the current fluid level "Li". It should be noted that the increase in the actual fluid ramp rate "AR" is performed based on multiplication of the third ramp rate factor "RF3' and the first ramp rate "RI". Further, when the fluid level "Li" increases such that the fluid level "LI" is in the first zone 152, the actual fluid ramp rate "AR" is increased linearly. In an example, the actual fluid ramp rate "AR-may be increased by double of the first ramp rate "RI" in the second zone 154. Alternatively, the actual fluid ramp rate "AR" may be increased by 25%, 50%, 75%, and the like.

[0052] Referring again to FIG. 2, a third response strategy for varying the actual flow rate "AF" of the fluid and the actual fluid ramp rate "AR" of the fluid will now be explained in detail. The third response strategy includes varying the actual flow rate "AF-and the actual fluid ramp rate "AR" based on the health of the pumps 104. In the third response strategy, the controller 134 may use the inputs from the pump health monitoring module 124 or any other sensors associated with the pumps 104 for varying the actual flow rate "AF" and the actual fluid ramp rate "AR". It should be noted that any sensors associated with the pumps 104 that provide an indication of the health of the pumps 104 may be used in the third response strategy.

100531 In the third response strategy, the controller 134 determines if some of the pumps 104 have failed so that the pumps 104 that are operating may be operated in a manner so as to deliver the desired flow rate "DF" at the desired fluid ramp rate "DR". In the third response strategy, a change in the actual flow rate -AF-or the actual fluid ramp rate "AR" through the well stimulation arrangement 100 may be controlled based on the failure of one or more pumps 104. In such situations, the desired flow rate "DF" and the desired fluid ramp rate "DR" is decided based on a target Hydraulic Horsepower (HHP) of the pumps 104 that are in operation, a reserve load, and a maximum engine load. If available HI-IP of the pumps 104 that are in operation matches with the target HET, the controller 134 does not vary the actual flow rate "AF" or the actual fluid ramp rate "AR'.

[0054] However, if the available HHP is less than the target HHP, the controller 134 reduces the actual flow rate "AF" based on reduction in the actual fluid ramp rate "AR". It should be noted that a value by which the actual fluid ramp rate "AR" is reduced may be configured or determined based on a number of factors such as, but not limited to, a total number of the pumps 104 that have failed, a difference between the available HHP and the target BHP, and the like. Further, if reserve pumps are available at the well site, the actual flow rate "AF" and the actual fluid ramp rate "AR" are maintained until the reserve pumps start operating. Once the reserve pumps start operating, the actual flow rate "AF" and the actual fluid ramp rate "AR" may be increased to an original flow rate and fluid ramp rate at which the fluid was flowing before failure of some of the pumps 104.

10055] The controller 134 may be embodied as a single microprocessor or multiple microprocessors for receiving signals from various components of the system 110. Numerous commercially available microprocessors may be configured to perform the functions of the controller 134. It should be appreciated that the controller 134 may embody a microprocessor capable of controlling numerous functions. A person of ordinary skill in the art will appreciate that the controller 134 may additionally include other components and may also perform other functions not described herein.

Industrial Applicability

10056] The present disclosure relates to the system 110 for varying the actual flow rate "AF' and/or the actual fluid ramp rate "AR" of the fluid in the well stimulation arrangement 100. The system 110 described herein utilizes an automated flow control technique that protects the equipment of the well stimulation arrangement 100 and also ensures safety of personnel working at the well site. The system 110 described herein includes monitoring of the well head pressure i.e., the first pressure "P 1", the second pressure -P2-i.e., the individual pressure at the exit of the pumps 104, the exit flow rate "RI" at the exit of the pumps 104, the actual fluid ramp rate "AR", the fluid level "Li", and the health of the pumps 104 for determining if the actual flow rate "AU"' or the actual fluid ramp rate "AR" needs to be increased or decreased.

10057] The system 110 includes the controller 134 that controls the inlet of the pumps 104 to vary the actual flow rate "AF" of the fluid and the actual fluid ramp rate "AR" based on receipt of the input signals from various sensors associated with the system 110. The values of the actual flow rate "AF" and the actual fluid ramp rate "AR" are maintained in the predefined ranges thus protecting the equipment from failure, reducing downtime associated with the well stimulation arrangement 100, and increasing productivity at the well site.

10058] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof

Claims

Claims What is claimed is: 1 A system for varying flow of a fluid in a well stimulation arrangement, the system comprising: a vessel for holding the fluid therein; one or more pumps fluidly coupled with the vessel, wherein the one or more pumps pressurize the fluid received from the vessel, and wherein the one or more pumps are controllable to direct the fluid towards a well head at a desired flow rate and a desired fluid ramp rate; and a controller communicably coupled with the one or more pumps, wherein the controller is configured to: receive an input signal corresponding to at least one operating parameter of the well stimulation arrangement, wherein the at least one operating parameter includes one of a first pressure measured at the well head, a second pressure measured at an exit of the one or more pumps, an exit flow rate at the exit of the one or more pumps, a fluid level in the vessel, and a health of the one or more pumps; and control the one or more pumps for varying at least one of an actual flow rate of the fluid and an actual fluid ramp rate of the fluid based on receipt of the input signal