CA2684281A1 - System and method for crossflow detection and intervention in production wellbores - Google Patents

Abstract

A system and method for managing a production from a wellbore (50) that includes taking measurements relating to one or more selected parameters for each of the production zones (52a, 52b) over a time period and determining the occurrence of the cross flow in the wellbore using a trend of the one or more of the measurements. The system includes a processor (150) that receives information relating to the measurements made over time relating to the selected parameters, wherein the processor determines or predicts the occurrence of the cross flow from a trend of at least one of the measurements.

Description

SYSTEM AND METHOD FOR CROSSFLOW DETECTION AND
INTERVENTION IN PRODUCTION WELLBORES
Inventors: Brian L. Thigpen; Guy P. Vachon; Garabed Yeriazarian;
Jaedong Lee; Chee M. Chok; Clark Sann; Xin Liu BACKGROUND OF THE DISCLOSURE

2. Field of the Disclosure [0001] This disclosure relates generally to detecting cross flow in production wellbores and for managing production of fluids from the wellbores in response to the detection of the cross flow.

3. Background of the Art [0002] Wellbores are often drilled through formations that include two or more production zones. Such wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated from each other by installing a packer between the production zones. Fluid from each production zone entering the wellbore is drawn into a tubing that runs to the surface. Normally, the pressure in the wellbore proximate a lower production zone is greater than the pressure proximate an upper or shallower production zone, which forces the fluid from the lower and upper production zones to the surface.

[0003] Due to anomalies in the formations surrounding the wellbore, sometimes the pressure proximate the upper production zone can exceed the pressure proximate the lower production zone, causing the fluid from the upper production zone to flow toward the lower production zone, a phenomenon referred to as the cross flow.
In such situations, the fluid from the lower production zones may not flow to the surface.
Cross flow is often detected a certain time after it has occurred and in some cases it may cause damage to the equipment and devices in the wellbore, including damage to the electrical submersible pump (when present in the wellbore) and other wellbore devices and in other cases it may damage the wellbore and the formations surrounding the wellbore. Therefore, there is a need for an improved system and method that detect the cross flow and takes appropriate corrective actions at the wellsite.

SUMMARY OF THE DISCLOSURE

[0004] In one aspect, cross flow is detected by: taking at least one first measurement indicative of a selected parameter of a first production zone, taking at least one second measurement indicative of the selected parameter of a second production zone, and determining occurrence of the cross flow a trend relating to at least one of the first measurement and the second measurement. The selected parameter may pressure, temperature or fluid flow rate. The method may use nodal analysis and/or a neural network to predict the occurrence of the cross flow. The method may determine the cross flow from the rate of change of one of the parameters, such as the rate of change of the pressure corresponding to the upper and/or the lower zone.

[0005] Upon detection or based on the predicted cross flow, the method may determine changes that may be made to the operation of one or more devices, which changes when made may reduce or eliminate the cross flow condition or its effects.
In one aspect, certain devices relating to the wellbore may be automatically set to new operating positions. The changes may include actions such as (i) closing a choke; (ii) changing frequency of an electrical submersible pump pumping fluid; (iii) changing a supply amount of an additive to the wellbore; (v) closing a zone; (vi) isolating a zone;
(vi) decreasing surface pressure; and (vii) opening a surface choke.

[0006] The apparatus utilized to detect the cross flow may include a processor that receives an input relating to a first measurement of a selected parameter corresponding to a first production zone and a second measurement of the selected parameter relating to a second production zone when each of the production zones is producing a formation fluid into a well. The processor processes data relating to the measurements to predict or detect the cross flow. The selected parameter may be chosen from a group consisting of: (i) pressure; (ii) temperature; and (iii) fluid flow rate. The processor in one aspect may use a model and performs a nodal analysis to determine the occurrence of the cross flow condition. The measurements may be made continuously or periodically over time. In one aspect, the processor may determine a rate of change or trend of at least one of the first measurements and the second measurements and detect or predict the occurrence of the cross flow based at least in part on the determined trend or the rate of change. In one aspect, the processor may send one or more alarm conditions that also may be displayed on a display for use by an operator and such conditions may be sent to a remote location via any suitable communication link, including the Internet.

[0007] The processor also may be configured to suggest adjustments to one or more operating parameters of the wellbore to limit or eliminate the negative impact of an anticipated or actual cross flow condition, which may include, but not are limited to (i) operating a choke; (ii) changing frequency of an electrical submersible pump pumping fluid; (iii) operating a sliding sleeve valve; (iv) changing a supply of the amount of an additive to the wellbore; (v) closing of a zone; (vi) isolating a zone; (vi) decreasing the surface pressure; and (vii) opening a surface choke.

[0008] One or more computer models and computer programs may be stored in a computer-readable medium that is accessible to the processor. The processor executes the instructions contained in the computer programs to perform one or more of the functions and methods described herein. In one aspect, the programs include a model that uses a nodal analysis or neural network to detect or predict the occurrence of the cross flow, determine the suggested changes and perform a net present value based on the new settings.

[0009] Examples of the more important features of system and method for cross flow detection and intervention in production wells have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated.
There are, of course, additional features that will be described hereinafter and which will form the subject of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[00010] For a detailed understanding of the system and method for detecting cross flow and well intervention described herein, reference should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements generally have been given like numerals, wherein:

FIGS. 1A and 1B collectively show a schematic diagram of a production wellbore system for producing fluid from multiple production zones;
FIG 2 is an exemplary functional diagram of a control system 200 that may be utilized to perform various measurements and data to predict an occurrence of a cross-flow condition relating to a production well system, including the well system shown in FIGS. 1A and 1B; and FIG 3 is an exemplary graph showing pressure measurements over time corresponding to the exemplary production zones shown in FIG 1A that may be used for detecting cross flow.

a q CA 02684281 2009-10-15 DETAILED DESCRIPTION OF THE DISCLOSURE

[00011] FIGS. 1A and 1B collectively show a schematic diagram of a production well system 10. FIG. 1A shows a production well 50 that has been configured using exemplary equipment, devices and sensors that may be utilized to implement the concepts and methods described herein. FIG 1B shows exemplary surface equipment, devices, sensors, controllers, computer programs, models and algorithms that may be utilized to: detect and/or predict an occurrence of a cross flow condition; send appropriate messages and alarms to an operator; determine adjustments to be made or actions to be taken relating to the various operations of the well 50 to mitigate or eliminate negative effects of the potential or actual occurrence of the cross flow condition; automatically control any one or more of the devices or equipment in the system 10; establish a two-way communication with one or more remote locations and/or controllers via appropriate links, including the Internet, wired or wireless links; and automatically take one or more actions.

[00012] FIG 1A shows a well 50 formed in a formation 55 that is producing formation fluid 56a and 56b from two exemplary production zones 52a (upper production zone) and 52b (lower production zone) respectively. The well 50 is shown lined with a casing 57 that has perforations 54a adjacent the upper production zone 52a and perforations 54b adjacent the lower production zone 52b. A packer 64, which may be a retrievable packer, positioned above or uphole of the lower production zone perforations 54a isolates the lower production zone 52b from the upper production zone 52a. A screen 59b adjacent the perforations 54b the well may be installed to prevent or inhibit solids, such as sand, from entering into the wellbore from the lower production zone 54b. Similarly, a screen 59a may be used adjacent the upper production zone perforations 59a to prevent or inhibit solids from entering into the well 50 from the upper production zone 52a.

[00013] The formation fluid 56b from the lower production zone 52b enters the annulus 51a of the well 50 through the perforations 54a and into a tubing 53 via a flow control valve 67. The flow control valve 67 may be a remotely control sliding sleeve valve or any other suitable valve or choke that can regulate the flow of the fluid from the annulus 51a into the production tubing 53. An adjustable choke 40 in the tubing 53 may be used to regulate the fluid flow from the lower production zone 52b to the surface 112. The formation fluid 56a from the upper production zone 52a enters the annulus 51b (the annulus portion above the packer 64a) via perforations 54a. The formation fluid 56a enters production tubing or line 45 via inlets 42. An adjustable valve or choke 44 associated with the line 45 regulates the fluid flow into the line 45 and may be used to adjust flow of the fluid to the surface 112.
Each valve, choke and other such device in the well may be operated electrically, hydraulically, mechanically and/or pneumatically from the surface. The fluid from the upper production zone 52a and the lower production zone 52b enter the line 46. FIGS.

and 1B collectively show a schematic diagram of a production wellbore system that includes various flow control devices, sensors in the wellbore and the surface, controllers, computer programs and algorithms that may be used collectively to implement the methods and concepts described herein according to one embodiment of the disclosure. FIG. 1A shows a production wellbore 50 that has been configured using exemplary equipment, devices and sensors that may be utilized to implement the concepts and methods described herein. FIG. 1B shows exemplary surface equipment, devices, sensors, controllers and computer programs that may be utilized to detect or predict a cross flow condition and to manage the operations of the various devices in the system 10.

[00014] The formation fluid 56a enters production line 45 via inlets 42. An adjustable valve or choke 44 associated with the line 45 regulates the fluid flow into the line 45 and may be used to adjust fluid flowing to the surface. Each valve, choke and other such device in the wellbore may be operated electrically, hydraulically, mechanically and/or pneumatically. The fluid from the upper production zone 52a and the lower production zone 52b enter the line 46.

[00015] In cases where the formation pressure is not sufficient to push the fluid 56a and/or fluid 56b to the surface, an artificial lift mechanism, such as an electrical submersible pump (ESP, a gas lift system, a beam pump, a jet pump, a hydraulic pump or a progressive cavity pump) may be utilized to pump the fluids from the well to the surface 112. In the system 10, an ESP 30 in a manifold 31 receives the formation fluids 56a and 56b and pumps such fluids via tubing 47 to the surface 112.
A cable 34 provides power to the ESP 30 from a surface power source 132 (FIG
1B) that is controlled by an ESP control unit 130. The cable 134 also may include two-way data communication links 134a and 134b, which may include one or more electrical conductors or fiber optic links to provide a two-way signals and data link between the ESP 30, ESP sensors SE and the ESP control unit 130. The ESP
control unit 130, in one aspect, controls the operation of the ESP 30. The ESP control unit 130 may be a computer-based system that may include a processor, such as a microprocessor, memory and programs useful for analyzing and controlling the operations of the ESP 30. In one aspect, the controller 130 receives signals from sensors SE (FIG 1A) relating to the actual pump frequency, flow rate through the ESP, fluid pressure and temperature associated with the ESP 30 and may receive measurements or information relating to certain chemical properties, such as corrosion, scale, hydrate, paraffin, emulsion, asphaltene, etc. and in response thereto or other determinations control the operation of the ESP 30. In one aspect, the ESP
control unit 130 may be configured to alter the ESP pump speed by sending control signals 134a in response to the data received via link 134b or instructions received from another controller. The ESP control unit 130 may also shut down power to the ESP via the power line 134. In another aspect, ESP control unit 130 may provide the ESP related data and information (frequency, temperature, pressure, chemical sensor information, etc.) to the central controller 150, which in turn may provide control or command signals to the ESP control unit 130 to effect selected operations of the ESP
30.

[00016] A variety of hydraulic, electrical and data communication lines (collectively designated by numeral 20 (FIG 1A)) are run inside the well 50 to operate the various devices in the well 50 and to obtain measurements and other data from the various sensors in the well 50. As an example, a tubing 21 may supply or inject a particular chemical from the surface into the fluid 56b via a mandrel 36.
Similarly, a tubing 22 may supply or inject a particular chemical to the fluid 56a in the production tubing via a mandrel 37. Lines 23 and 24 may operate the chokes and 42 and may be used to operate any other device, such as the valve 67. Line may provide electrical power to certain devices downhole from a suitable surface power source.

[00017] In one aspect, a variety of other sensors are placed at suitable locations in the well 50 to provide measurements or information relating to a number of downhole parameters of interest. In one aspect, one or more gauge or sensor carriers, such as a carrier 15, may be placed in the production tubing to house any number of suitable sensors. The carrier 15 may include one or more temperature sensors, pressure sensors, flow measurement sensors, resistivity sensors, sensors that provide information about density, viscosity, water content or water cut, and chemical sensors that provide information about scale, corrosion, paraffin, hydrate, asphaltene, etc.
Density sensors may be fluid density measurements for fluid from each production zone and that of the combined fluid from two or more production zones. The resistivity sensor or another suitable sensor may provide measurements relating to the water content or the water cut of the fluid mixture received from each production zones. Other sensors may be used to estimate the oil/water ratio and gas/oil ratio for each production zone and for the combined fluid. The temperature, pressure and flow sensors provide measurements for the pressure, temperature and flow rate of the fluid in the line 53. Additional gauge carriers may be used to obtain pressure, temperature and flow measurements, water content relating to the formation fluid received from the upper production zone 52a. Additional downhole sensors may be used at other desired locations to provide measurements relating to chemical characteristics of the downhole fluid, such as paraffin, hydrate, sulfide, scale, corrosion, asphaltene, emulsion, etc. Additionally, sensors Si-Sm may be permanently installed in the wellbore 50 to provide acoustic or seismic measurements, foirnation pressure and temperature measurements, resistivity measurements and measurements relating to the properties of the casing 51 and formation 55. Such sensors may be installed in the casing 57 or between the casing 57 and the formation 55. Additionally, the screen 59a and/or screen 59b may be coated with tracers that are released due to the presence of water, which tracers may be detected at the surface or downhole to detect and/or predict the occurrence of a cross flow condition. Sensors also may be provided at the surface, such as a sensor for measuring the water content in the received fluid, total flow rate for the received fluid, fluid pressure at the wellhead, temperature, etc.

[00018] In general, sufficient sensors may be suitably placed in the well 50 to obtain measurements relating to each desired parameter of interest. Such sensors may include, but are not limited to, sensors for measuring pressures corresponding to each production zone, pressure along the wellbore, pressure inside the tubing carrying the formation fluid, pressure in the annulus, temperatures at selected places along the wellbore, fluid flow rates corresponding to each of the production zones, total flow rate, flow through the ESP, ESP temperature and pressure, chemical sensors, acoustic or seismic sensors, optical sensors, etc. The sensors may be of any suitable type, including electrical sensors, mechanical sensors, piezoelectric sensors, fiber optic sensors, optical sensors, etc. The signals from the downhole sensors may be partially or fully processed downhole (such as by a microprocessor and associated electronic circuitry that is in signal or data communication with the downhole sensors and devices) and then communicated to the surface controller 150 via a signaUdata link, such as link 101. The signals from downhole sensors may be sent directly to the controller 150 as described in more detail herein.

[00019] Referring back to FIG 1B, the system 10 is further shown to include a chemical injection unit 120 at the surface for supplying additives 113a into the well 50 and additives 113b to the surface fluid treatment unit 170. The desired additives 113a from a source 116a (such as a storage tank) thereof may be injected into the wellbore 50 via injection lines 21 and 22 by a suitable pump 118, such as a positive displacement pump. The additives 113a flow through the lines 21 and 22 and discharge into the manifolds 30 and 37. The same or different injection lines may be used to supply additives to different production zones. Separate injection lines, such as lines 21 and 22, allow independent injection of different additives at different well depths. In such a case, different additive sources and pumps are employed to store and to pump the desired additives. Additives may also be injected into a surface pipeline, such as line 176 or the surface treatment and processing facility such as unit 170.

[00020] A suitable flow meter 120, which may be a high-precision, low-flow, flow meter (such as gear-type meter or a nutating meter), measures the flow rate through lines 21 and 22, and provides signals representative of the corresponding flow rates. The pump 118 is operated by a suitable device 122, such as a motor or a compressed air device. The pump stroke and/or the pump speed may be controlled by the controller 80 via a driver circuit 92 and control line 122a. The controller 80 may control the pump 118 by utilizing programs stored in a memory 91 associated with the controller 80 and/or instructions provided to the controller 80 from the central controller or processor 150 or a remote controller 185. The central controller communicates with the controller 80 via a suitable two-way link 85. The controller 80 may include a processor 92, resident memory 91, for storing programs, tables, data and models. The processor 92, utilizing signals from the flow measuring device received via line 121 and programs stored in the memory 91 determines the flow rate of each of the additives and displays such flow rates on the display 81. A
sensor 94 may provide information about one or more parameters of the pump, such the pump speed, stroke length, etc. The pump speed or stroke, as the case may be, is increased when the measured amount of the additive injected is less than the desired amount and decreased when the injected amount is greater than the desired amount. The controller 80 also includes circuits and programs, generally designated by numeral 92 to provide interface with the onsite display 81 and to perform other desired functions.
A level sensor 94a provides information about the remaining contents of the source 116. Alternatively, central controller 150 may send commands to controller 80 relating to the additive injection or may perform the functions of the controller 80.

[00021] While FIGS. 1A and 1B illustrate one production well penetrating through two production zones, however, it should be understood that an oil field can include a variety of wells, each interesting one or more production zones. The system, methods, tools and devices shown and described herein may be utilized in any number of such wells and may be configured to suit the particular needs of the wells.

[00022] FIG 2 shows a functional diagram of a production well system 200 that may be utilized to detect and/or predict cross flow, determine actions that may be taken to mitigate the effects the cross flow condition, send messages to an operator and remote locations, automatically take certain actions, compute production rates, perform economic analysis and to perform other operations relating to a production well system, including the well system 10 of FIGS. 1A and 1B.

[00023] System 200 includes a central control unit or controller 150 that includes one or more processors, such as a processor 152, suitable memory devices 154 and associated circuitry 156 that are configured to perform various functions and methods described herein. The system 200 includes a database 230 stored in a suitable computer-readable medium that is accessible to the processors 152. The database 230 may include: (i) well completion data including, but not limited to, the types and locations of the sensors in the well, sensor parameters, types of devices and their parameters, including choke type and sizes, choke positions, valve type and sizes, valve positions, casing thickness, cement thickness, well diameter, well profile, etc.;
(ii) formation parameters, such as rock type for various formation layers, porosity, permeability, mobility, resistivity, depth of each formation layer and production zone, inclination, etc.; (iii) sand screen parameters; (iv) tracer information; (v) ESP
parameters, such as horsepower, frequency range, operating pressure range, maximum pressure differential across the ESP, operating temperature range, and a desired operating envelope; (vi) historical well performance data, including production rates over time for each production zone, pressure and temperature values over time for each production zone and wells in the same or nearby fields; (vii) current and prior choke and valve settings; (viii) intervention and remedial work information;
(ix) sand and water content corresponding to each production zone over time; (x) initial seismic data (two- or three-dimensional maps) and updated seismic data (four-dimensional seismic maps); (xi) waterfront monitoring data; (xii) microseismic data that may relate to seismic activity caused by a fluid front movement, fracturing, etc.;
(xii) inspection logs, such as obtained by using acoustic or electrical logging tools that provide an image of the casing showing pits, gauges, holes, and cracks in the casing, condition of the cement bond between the casing and the well wall, etc.; and (xiii) any other data that may be useful for detecting a cross flow, determining the health of the downhole devices, determining the actions to be taken upon detection or prediction of the cross flow, monitoring the effects of taking the actions so as to recover the hydrocarbons at an enhanced or optimized rate from the we1150.

[00024] During the life of a well, one or more tests, collectively designated by numeral 224, are typically performed to estimate the health of various well elements and various parameters of the production zones and the formation layers surrounding the well. Such tests may include, but are not limited to: casing inspection tests using electrical or acoustic logs for determining the condition of the casing and formation properties; well shut-in tests that may include pressure build-up or pressure transients, temperature and flow tests; seismic tests that may use a source at the surface and seismic sensors in the well to determine water front and bed boundary conditions; microseismic measurement responsive to a downhole operation, such as a fracturing operation or a water injection operation; fluid front monitoring tests;
secondary recovery tests, etc. All such test data 224 may be stored in a memory and provided to the processor 152 for monitoring the production from well 50, performing analysis for determining the health of various equipment and for enhancing, optimizing or maximizing production from the well 50 and the reservoir.

[00025] Additionally, the processor 152 of system 200 may periodically or continually access the downhole sensor measurement data 222, surface measurement data 226 and any other desired information or measurements 228. The downhole sensor measurements 222 includes, but are not limited to: information relating to pressure; temperature; flow rates; water content or water cut; resistivity;
density;
viscosity; sand content; chemical characteristics or compositions of fluids, including the presence, amount and location of corrosion, scale, paraffin, hydrate and asphaltene; gravity; inclination; electrical and electro-magnetic measurements; oil/gas and oil/water ratios; and choke and valve positions. The surface measurements include, but are not limited to: flow rates; pressures; choke and valve positions; ESP
parameters; water content determined at the surface; chemical injection rates and locations; tracer detection information; etc.

[00026] The system 200 also includes programs, models and algorithms 232 embedded in one or more computer-readable media that are accessible to the processor 152 to execute instructions contained in the programs. The processor may utilize one or more programs, models and algorithms to perform the various functions and methods described herein. In one aspect, the programs, models and algorithms 232 may be in the form of a well performance analyzer (WPA) 260 that is used by the processor 152 to analyze some or all of the measurement data 222, 226, test data 224, information in the database 230 and any other desired information made available to the processor to detect and/or predict cross flow, determining an action plan or set of desired actions to be taken, simulate the effects of such actions, perform comparative analysis between competing sets of potential action plans, monitor the effects of the actual actions taken and perform an economic analysis, such as a net present value analysis. The well performance analyzer may use a forward looking b CA 02684281 2009-10-15 model, such a nodal analysis, neural network, an iterative process or another algorithm.

[00027] Referring now to FIG. 1A, under normal operating conditions of the well 50, pressure corresponding to the lower production zone 52b will be greater than the pressure corresponding to the upper production zone 52a. Under such a condition, the formation fluid 56a from the upper production zone will flow toward the surface as shown by arrows 77A. However, under certain conditions, the formation pressure "Pu" corresponding to the upper production zone 52a may start to increase and eventually become greater than the pressure "PP" of the lower production zone 52b.
As this pressure shift occurs, the formation fluid from the upper production zone starts to flow toward the lower production zone, as shown by the arrows 77B. At some point in time the pressure Pu and Pl cross over and the fluid from the upper production zone starts to flow downhole.

[00028] FIG 3 shows a hypothetical pressure graph 300 showing pressure versus time corresponding to the upper and lower production zones for a scenario under which a pressure cross-over occurs. Pressure is shown along the vertical axis, while time is shown along the horizontal axis. In graph 300, the pressure curve 202 corresponds to Pu (the pressure corresponding to the upper production zone) and the pressure curve 204 corresponds to Pl, (the pressure corresponding to the lower production zone). In the example of FIG. 3, at approximately time 210 the pressure Pu starts to increase and the pressure PI starts to decrease. The two pressures cross over at time 220 and Pu thereafter becomes greater than P1. Under such a scenario, the fluid produced by the upper production zone may drain into the lower production zone, or the fluid from the lower production zone may not be lifted to the surface, thereby causing loss of hydrocarbons. Such a condition may cause damage to one or more devices in the wellbore, such as the ESP 30 and also may cause damage to a formation or the wellbore in general. It should be appreciated that the scenario of FIG 3 is merely one of several scenarios under which a cross flow may occur.

[00029] In the system 200, the controller 150, in one aspect, continually monitors the pressures Pu and PI, utilizes the well performance analyzer 260 and detects the occurrence of a cross-flow condition. The well performance analyzer may predict a potential cross flow condition from the trend of the pressures Pu and PI and may estimate the time or time period and the severity of the predicted occurrence of the cross-flow condition. The well performance analyzer 260 may utilize a nodal analysis, neural network, or other models and/or algorithms to detect or predict the cross flow condition. The well performance analyzer may utilize current measurements of pressure, flow rates, temperature, historical, laboratory or other synthetic data to detect or predict the cross flow condition and the actual or expected time of the occurrence of the cross flow. The models may utilize or take into account any number of factors, such as the: amount or percent of percent pressure in the wellbore that is above the formation pressure and the length of time for which such a pressure condition has been present; rate of change of the pressures Pu and/or PI;
actual PI and Pu values; difference between the pressures Pl and Pu; actual temperatures of the upper and lower production zones; difference in the temperatures between the upper and lower production zones; annulus (upper zone) being greater than the pressure in the tubing (lower zone) while the lower zone is open for producing fluids; flow measurements from each of the production zones; a fluid flow downhole approaching a cross flow condition; and other desired factors.

[00030] Upon the detection or prediction of a cross flow condition, the processor 152 using the well performance analyzer 260 and other programs 232 determines the action or actions that may be taken to mitigate and/or eliminate the negative effects of the cross flow condition. Such actions may include, but are not limited to:
altering flow from a particular production zone; shutting-in a particular zone or the entire well; increasing fluid flow from one production zone while decreasing the fluid from another production zone; altering the operation of an artificial lift mechanism, such as altering the frequency of an ESP; changing a chemical injection rate;
performing a secondary operation, such as fluid injection into a formation, etc. The well performance analyzer 260 may determine the new settings of the various devices in the system 10 that will mitigate or eliminate the potential negative effects of the cross flow. The desired settings may include new settings for chokes, valves, ESP, chemical injection, etc. These settings may be chosen based on any selected criteria, including an economic analysis, such as a net present value, optimizing or maximizing production until a remedial work is performed.

[00031] Once the central controller 150 using the well performance analyzer and/or other programs and algorithms detects an actual or potential cross flow condition it sends messages, alarms and reports 262 relating to the cross flow condition and the well operations. Such information may include specific actions for the operator to take, the actions that are automatically taken by the controller 150, net present analysis information, plots relating to the cross flow condition, new settings of the various devices, etc. as shown at 260. These messages may be displayed at a suitable display located at one or more locations, including at the well site and/or at a remote control unit 185. The information may be transmitted by any suitable data link, including an Ethernet connection and the Internet 272 and may be any form, such as text, plots, simulated picture, email, etc. The information sent by the central controller may be displayed at any suitable medium, such as a monitor. The remote locations may include client locations or personnel managing the well from a remote office. The central controller 150 utilizing data, such as current choke positions, ESP
frequency, downhole choke and valve positions, chemical, injection unit operation and any other information 226 may determine one or more adjustments to be made or actions to be taken relating to the operation of the well, which operations when implemented are expected to mitigate or eliminate certain negative effects of the actual or potential cross flow condition on the well 50.

[00032] The well performance analyzer, in one aspect, may use a forward looking model, which may use a nodal analysis, neural network or another algorithm to estimate or assess the effects of the suggested actions and to perform an economic analysis, such as a net present value analysis based on the estimated effectiveness of the actions. The well performance analyzer also may estimate the cost of initiating any one or more of the actions and may perform a comparative analysis of different or alternative actions. The well performance analyzer also may use an iterative process to arrive at an optimal set of actions to be taken by the operator and/or the controller 150. The central controller may continually monitor the well performance and the effects of the actions 264 and sends the results to the operator and the remote locations. The central controller may update the models, expected flow rates from the well based on the new settings as shown at 234.

[00033] In one aspect, the central controller 150 may be configured to wait for a period of time for the operator to take the suggested actions (manual adjustments 265) and in response to the adjustments made by the operator determine the effects of such changes on the cross flow situation and the performance of the well. The controller may send additional messages when the operator fails to take an action and may initiate actions.

[00034] In another aspect, the central controller 150 may be configured to automatically initiate one or more of the recommended actions, for example, by sending command signals to the selected device controllers, such as to ESP
controller 242 to adjust the operation of the ESP 30; control units or actuators (160, FIG IA and element 240) that control downhole chokes 244; downhole valves 246; surface chokes 249; chemical injection control unit 250; other devices 254; etc. Such actions may be taken in real time or near real time. The central controller 150 continues to monitor the effects of the actions taken 264. In another aspect, the central controller 150 or the remote controller 185 may be configured to update one or more models/algorithms/programs 234 for further use in the monitoring of the well.
Thus, the system 200 may operate in a closed-loop form to continually monitor the performance of the well, detect and/or predict cross flow conditions, determine actions that will mitigate negative effects of cross flow, determine the effects of any action taken by the operator, perform economic analysis so as to enhance or optimize production from one or more production zones.

[00035] The central controller 150 may be configured or programmed to effect the recommended actions directly or through other control units, such as the ESP
control unit 130 and the additive injection controller 80. In another aspect, the controller may perform a nodal analysis to determine the desired changes or actions and proceed to effect the changes as described above. In another aspect, the central processor may transmit information to a remote controller 185 via a suitable link, such a hard link, wireless link or the Internet, and receive instructions from the remote controller 185 relating to the recommended actions. In another aspect, the central controller or the remote controller may perform a simulation based on the recommended action to determine the effect such actions will have on the operations of the wellbore.
If the simulation shows that the effects fail to meet certain preset criterion or criteria, the processor performs additional analysis to determine a new set of actions that will meet the set criterion or criteria. It should be understood that separate controllers, such as controllers 80, 130 and 150 are shown merely for ease of explaining the methods and concepts described herein. In embodiments, a single local controller, such as controller 150 or a remote controller, such as controller 185, or a combination of any such controllers may be utilized to cooperatively control the various aspects of the system 10. Additionally, the central controller 150 may update the database management system 199 based on the operating conditions of the wellbore, which information may be used to update the models used by the controller 150 for further monitoring and management of the wellbore 50. The communication via the Ethernet or the Internet enables two-way communication among the operator and personnel at remote locations and allows such personnel log into the database and monitor and control the operation of the well 50. Also, it should be understood that the present description refers to a well with two production zones merely for ease of explanation.
In aspects, embodiments can be utilized in connection with two or more wellbores, each of which may intersect the same production zones or different production zones.
Thus, while cross flow between two or more production zones intersected by the same wellbore have been discussed, it should be appreciated that system, methods and concepts described herein may be used to determine undesirable flow conditions between any number of production zones that are drained by the same or different wells. Additionally, it should be appreciated that a cross flow is only an illustrative of flow condition that can impact production efficiency. In aspects, embodiment can be configured to evaluate data from wellbore sensors to determine whether the data or data trends indicate the occurrence of any preset or predetermined flow condition.

[00036] As discussed herein, the disclosure, in one aspect, provides method for managing fluid production from a wellbore having at least two production zones that includes taking at least one first measurement indicative of a selected parameter of a first production zone, taking at least one second measurement indicative of the selected parameter of a second production zone, and determining occurrence of a cross flow condition from a trend relating to at least one of the first measurement and the second measurement. The selected parameter may: (i) pressure; (ii) temperature;
or (iii) fluid flow rate. The method may use nodal analysis to predict the occurrence of the cross flow condition. The method may further take the first measurement and the second measurement over a time period and determine therefrom a rate of change of one of the first measurement and the second measurement; and determine the occurrence of the cross flow condition based at least in part on the determined rate of change of at least one of the first measurement and the second measurement. In the method, alarm conditions may be sent upon the determination of the occurrence of the cross flow condition. The method, in one aspect, determines changes that may be made to the operation of one or more devices, which when made may reduce or eliminates the cross flow condition. In one aspect, certain devices relating to the wellbore are automatically are set to new values. The changes can include actions such as (i) closing a choke; (ii) changing frequency of an electrical submersible pump pumping fluid; (iii) changing supply amount of an additive to the wellbore;
(v) closing a zone; (vi) isolating a zone; (vi) decreasing surface pressure; and (vii) opening a surface choke.

[00037] The disclosure also provides an apparatus that includes a processor that receives an input relating to a first measurement of a selected parameter corresponding to a first production zone and a second measurement of the selected parameter relating to the second production zone, each of the production zones producing a formation fluid into a wellbore, wherein the processor determines an occurrence of a cross flow condition in the wellbore from a trend relating to at least one of the first measurement and the second measurement. The selected parameters may be chosen from a group consisting of: (i) pressure; (ii) temperature; and (iii) fluid flow rate. The processor in one aspect may use a model and peiforms a nodal analysis to determine the occurrence of the cross flow condition. The measurements may be made continuously or periodically over time. In one aspect, the processor determines a rate of change of at least the first measurement and the second measurement and determines the occurrence of the cross flow condition based at least in part on the determined rate of change. In one aspect, the processor may send one or more alarm conditions that also may be displayed on a display for use by an operator and such conditions may be sent to a remote location via any suitable communication link, including the Internet. The processor also may be configured to suggest adjustments to one or more operating parameters of the wellbore to limit or eliminate the negative impact of an anticipated or actual cross flow condition, which may include, but not are limited to (i) operating a choke; (ii) changing frequency of an electrical submersible pump pumping fluid; (iii) operating a sliding sleeve valve; (iv) changing a supply of the amount of an additive to the wellbore; (v) closing of a zone;
(vi) isolating a zone; (vi) decreasing the surface pressure; and (vii) opening a surface choke. One or more computer models and computer programs are stored in a computer-readable medium that is accessible to the processor and the processor executes the instructions contained in the programs to perform the functions and methods described herein. In one aspect, the programs include a model that enables the controller to perform nodal analysis to predict the occurrence of the cross flow and to simulate the wellbore conditions based on the suggested changes and other inputs relating to the settings of the various devices in the system.

[00038] While the foregoing disclosure is directed to certain specific exemplary embodiments, various modifications will be apparent to those skilled in the art. It is intended that all modifications within the scope of the appended claims be embraced by the foregoing disclosure.

Claims (20)

1. A method of detecting cross flow in a wellbore, comprising:
taking a first measurement indicative of a first parameter of a first production zone;
taking a second measurement indicative of a second parameter of a second production zone; and determining an occurrence of a cross flow condition from a trend relating to at least one of the first measurement and the second measurement.

2. The method of claim 1, wherein the first parameter or the second parameter is selected from a group consisting of: (i) pressure; (ii) temperature; and (iii) fluid flow rate.

3. The method of claim 1, wherein determining the occurrence of a cross flow condition comprises using a nodal analysis to predict the occurrence of the cross flow condition.

4. The method of claim 1 further comprising:
- taking the first measurement and the second measurement over a time period;
- determining a rate of change of one of the first measurement and the second measurement; and determining the occurrence of the cross flow condition based at least in part on the determined rate of change of at least one of the first measurement and the second measurement.

5. The method of any of claims 1 and 3-4 further comprising sending an alarm condition indicating the cross flow condition.

6. The method of any of claims 1 and 3-4 further comprising determining a change in an operation of at least one flow control device associated with the wellbore, which change when made is expected to at least reduce an effect of the cross flow condition.

7. The method of any of claims 1 and 3-4 further comprising performing at least one operation to reduce an effect of the cross flow, which operation is selected from a group consisting of: (i) closing a choke; (ii) changing frequency of an electrical submersible pump; (iii) operating a valve; (iv) changing supply amount of an additive to the wellbore; (v) closing at least one of the first and second production zones; (vi) isolating at least one of the first and second production zones; (vi) decreasing a surface pressure; and (vii) opening a surface choke.

8. A computer-readable medium accessible to a processor for executing instructions contained in a computer program embedded in the computer-readable medium, the computer program comprising:
instructions to receive information relating to a first measurement indicative of a selected parameter of a first production zone and a second measurement indicative of a selected parameter of a second production zone; and instructions to determine occurrence of a cross flow condition from a trend relating to at least one of the first measurement and the second measurement.

9. The computer-readable medium of claim 8, wherein the selected parameter is chosen from a group consisting of: (i) pressure; (ii) temperature; and (iii) fluid flow rate.

10. The computer-readable medium of claim 8, wherein the computer program further comprises instructions to use a nodal analysis to determine the occurrence of the cross flow condition.

11. The computer-readable medium of claim 8, wherein the first measurement and the second measurement are taken over a time period, and wherein the computer program further comprises instructions to determine a rate of change of at least one of the first measurement and the second measurement; and instructions to determine the occurrence of the cross flow condition based at least in part on the determined rate of change of at least one of the first measurement and the second measurement.

12. The computer-readable medium of any of claims 8 and 10-11, wherein the computer program further comprises instructions to generate one or more recommendations that include at least one of: (i) close a choke; (ii) change frequency or speed of an electrical submersible pump; (iii) operate a valve; (iv) change supply amount of an additive to the wellbore; (v) close a production zone; (vi) isolate a production zone; (vi) decrease surface pressure; and (vii) open a surface choke.

13. An apparatus for managing production from a wellbore, comprising:
a processor that receives an input relating to a first measurement of a selected parameter corresponding to a first production zone and a second measurement relating to a selected parameter for a second production zone, each of the first and the second production zones producing a formation fluid, wherein the processor determines an occurrence of a cross flow condition in the wellbore from a trend relating to at least one of the first measurement and the second measurement.

14. The apparatus of claim 13, wherein the selected parameters for the first production zone and the second production zone are chosen from a group consisting of: (i) pressure; (ii) temperature; and (iii) fluid flow rate.

15. The apparatus of claim 13, wherein the processor uses a model and performs a nodal analysis to determine the occurrence of the cross flow condition.

16. The method of claim 13, wherein the first measurement and the second measurement each is taken over a time period and wherein the processor:
- determines a rate of change of one of the first measurement and the second measurement; and determines the occurrence of the cross flow condition based at least in part on the determined rate of change.

17. The apparatus of any of claims 13 and 15-16, wherein the processor further sends an alarm condition in response to the determination of the cross flow condition.

18. The apparatus of any of claims 13 and 15-16, wherein the processor further determines a desired change in an operation of at least one device associated with the wellbore, which change when made is expected to at least reduce an adverse effect of the cross flow condition.

19. The apparatus of any of claims 13 and 15-16, wherein the processor further sends signals for performing at least one operation in response to the determination of the occurrence of the cross flow condition, which operation is selected from a group consisting of: (i) operating a choke; (ii) changing a frequency or speed of an electrical submersible pump; (iii) operating a downhole valve; (iv) changing supply amount of an additive to the wellbore; (v) closing at least one of the production zones;
(vi) isolating at least one of the production zones; (vi) decreasing a surface pressure; and (vii) opening a surface choke.

20. The apparatus of claim 13, further comprising a computer program on a computer-readable medium accessible to the processor for executing instructions contained in the computer program, wherein the computer program includes a model to perform nodal analysis to predict the occurrence of the cross flow.