This section of this document is intended to introduce various aspects of the art that may be related to various aspects of the present disclosure described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the present invention. That such art is related in no way implies that it is prior art. The related art may or may not be prior art. It should therefore be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Wells are generally drilled into the ground or ocean bed to recover natural deposits of oil and gas, as well as other desirable materials that are trapped in geological formations in the Earth's crust. A well is typically drilled using a drill bit attached to the lower end of a “drill string.” Drilling fluid, or “mud,” is typically pumped down through the drill string to the drill bit. The drilling fluid lubricates and cools the drill bit, and it carries drill cuttings back to the surface in the annulus between the drill string and the wellbore wall.
For successful oil and gas exploration, it may be useful to have information about the subsurface formations that are penetrated by a wellbore. For example, one aspect of standard formation evaluation relates to the measurements of the reservoir fluid pressure and/or formation permeability, among other reservoir properties. These measurements may be used to predicting the production capacity and production lifetime of a subsurface formation.
One technique for measuring reservoir properties includes lowering a “wireline” tool into the well to measure formation properties. A wireline tool is a measurement tool that is suspended from a wireline in electrical communication with a control system disposed on the surface. The tool is lowered into a well so that it can measure formation properties at desired depths. A typical wireline tool may include a probe or other sealing device, such as a pair of packers, that may be pressed against the wellbore wall to establish fluid communication with the formation. This type of wireline tool is often called a “formation tester.” Using the probe, a formation tester measures the pressure of the formation fluids, generates a pressure pulse, which is used to determine the formation permeability. The formation tester tool also typically withdraws a sample of the formation fluid that is either subsequently transported to the surface for analysis or analyzed downhole.
In order to use any wireline tool, whether the tool be a resistivity, porosity or formation testing tool, the drill string is usually removed from the well so that the tool can be lowered into the well. This is called a “trip” uphole. Then, the wireline tools may be lowered to the zone of interest. A combination of removing the drill string and lowering the wireline tools downhole are time-consuming measures and can take up to several hours, depending upon the depth of the wellbore. Because of the great expense and rig time required to “trip” the drill pipe and lower the wireline tools down the wellbore, wireline tools are generally used only when additional information about the reservoir is beneficial and/or when the drill string is tripped for another reason, such as changing the drill bit size. Examples of wireline formation testers are described, for example, in U.S. Pat. Nos. 3,934,468; 4,860,581; 4,893,505; 4,936,139; 5,622,223; 6,719,049 and 7,380,599 all herein incorporated by reference in their entirety.
To avoid or minimize the downtime associated with tripping the drill string, another technique for measuring formation properties has been developed in which tools and devices are positioned near the drill bit in a drilling system. Thus, formation measurements are made during the drilling process and the terminology generally used in the art is “MWD” (measurement-while-drilling) and/or “LWD” (logging-while-drilling). A variety of downhole MWD and LWD drilling tools are commercially available. Further, formation measurements can be made in tool strings which do not have a drill bit but which may circulate mud in the borehole.
MWD typically refers to measuring the drill bit trajectory as well as wellbore temperature and pressure, while LWD typically refers to measuring formation parameters or properties, such as resistivity, porosity, permeability, and sonic velocity, among others. Real-time data, such as the formation pressure, facilitates making decisions about drilling mud weight and composition, as well as decisions about drilling rate and weight-on-bit, during the drilling process. While LWD and MWD have different meanings to those of ordinary skill in the art, that distinction is not germane to this disclosure, and therefore this disclosure does not distinguish between the two terms.
Formation evaluation tools capable of performing various downhole formation tests typically include a small probe and/or pair of packers that can be extended from a drill collar to establish hydraulic coupling between the formation and sensors and/or sample chambers in the tool. Some tools may use a pump to actively draw a fluid sample out of the formation so that it may be stored in a sample chamber in the tool for later analysis. Such a pump may be powered by a generator in the drill string that is driven by the mud flow down the drill string. Examples of LWD formation testers are described, for example, in U.S. Pat. App. Pub. Nos. 2008/0156486 and 2009/0195250 all herein incorporated by reference in their entirety.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.
Those skilled in the art, given the benefit of this disclosure, will appreciate that the disclosed apparatuses and methods have applications in operations other than drilling and that drilling is not necessary to practice this invention. While this disclosure is described in relation to sampling, the disclosed apparatus and method may be applied to other operations including injection techniques.
The phrase “formation evaluation while drilling” refers to various sampling and testing operations that may be performed during the drilling process, such as sample collection, fluid pump out, pretests, pressure tests, fluid analysis, and resistivity tests, among others. It is noted that “formation evaluation while drilling” does not necessarily mean that the measurements are made while the drill bit is actually cutting through the formation. For example, sample collection and pump out are usually performed during brief stops in the drilling process. That is, the rotation of the drill bit is briefly stopped so that the measurements may be made. Drilling may continue once the measurements are made. Even in embodiments where measurements are only made after drilling is stopped, the measurements may still be made without having to trip the drill string.
In this disclosure, “hydraulically coupled” or “hydraulically connected” and similar terms, may be used to describe bodies that are connected in such a way that fluid pressure may be transmitted between and among the connected items. The term “in fluid communication” is used to describe bodies that are connected in such a way that fluid can flow between and among the connected items. It is noted that hydraulically coupled or connected may include certain arrangements where fluid may not flow between the items, but the fluid pressure may nonetheless be transmitted. Thus, fluid communication is a subset of hydraulically coupled.
The surface system may further include drilling fluid or mud 12 stored in a pit 13 or tank at the wellsite. A mud pump 14 delivers drilling fluid 12 to the interior of drill string 4 via a port in swivel 5, causing the drilling fluid to flow downwardly through drill string 4 as indicated by the directional arrow 1a. The drilling fluid exits drill string 4 via ports in the drill bit 11, and then circulates upward through the annulus region between the outside of the drill string and the wall of the wellbore, as indicated by the directional arrows 1b. In this well known manner, the drilling fluid lubricates drill bit 11 and carries formation cuttings up to the surface as it is returned to pit 13 for recirculation.
The depicted bottomhole assembly (“BHA”) 10 includes a logging-while-drilling (“LWD”) module 20, a measuring-while-drilling (“MWD”) module 16, a roto-steerable system and motor 17, and drill bit 11. According ton one or more aspects of the present disclosure, LWD module 20 may be a downhole formation tester (e.g., sampling tool).
LWD module 20 is housed in a special type of drill collar, as is known in the art, and can contain one or a plurality of known types of logging tools. It will also be understood that more than one LWD and/or MWD module can be employed. LWD module includes capabilities for measuring, processing, and storing information, as well as for communicating with the surface equipment.
MWD module 16 is also housed in a special type of drill collar, as is known in the art, and can contain one or more devices for measuring characteristics of the drill string and drill bit. BHA 10 may include an apparatus for generating electrical power to the downhole system. This may typically include a mud turbine generator powered by the flow of the drilling fluid, it being understood that other power and/or battery systems may be employed. The MWD module may include, for example, one or more of the following types of measuring devices: a weight-on-bit measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a stick slip measuring device, a direction measuring device, and an inclination measuring device.
BHA 10 may include an electronics module or subsurface controller (e.g., electronics, telemetry), generally denoted as 18. Subsurface controller 18 (e.g., controller) may provide a communications link for example between a controller 19 and the downhole equipment (e.g., the downhole tools, sensors, pumps, gauges, etc.). Controller 19 is an electronics and processing package that can be disposed at the surface. Electronic packages and processors for storing, receiving, sending, and/or analyzing data and signals may be provided at one or more of the modules as well.
Controller 19 may be a computer-based system having a central processing unit (“CPU”). The CPU is a microprocessor based CPU operatively coupled to a memory, as well as an input device and an output device. The input device may comprise a variety of devices, such as a keyboard, mouse, voice-recognition unit, touch screen, other input devices, or combinations of such devices. The output device may comprise a visual and/or audio output device, such as a monitor having a graphical user interface. Additionally, the processing may be done on a single device or multiple devices. Controller 19 may further include transmitting and receiving capabilities for inputting or outputting signals.
Pumpout module 30 (e.g., pump module) includes a displacement unit (“DU”) 32 (e.g., reciprocating piston, pump) actuated by a power source 34 to pump fluid (e.g., wellbore fluid, formation fluid, sample fluid) at least partially through tool 20. Such pumping may include, for example, drawing fluid into the tool, discharging fluid from the tool, and/or moving fluid from one location to another location with the tool, as are well known in the art. Examples of bi-directional displacement units (e.g., pumps) are disclosed for example in U.S. Pat. Nos. 5,303,775 and 5,377,755, which are incorporated herein by reference. Power source 34 may be, for example, a hydraulic pump or motor driving a mechanical shaft. An example of a power source including one or more hydraulic pumps is disclosed in U.S. Pat. Appl. Publ. No. 2009/0044951 which is incorporated herein by reference. An example of a power source including a motor driving a mechanical shaft is disclosed in U.S. Pat. Appl. Publ. No. 2008/0156486 which is incorporated herein by reference. A power source gauge 36 (e.g., sensor) is depicted connected with power source 34 that may measure, for example, the force, hydraulic pressure (e.g., Bourne gauge, etc.), electric current or motor torque. In
The solenoid SOL3 and the associated poppet valve network is provided to reciprocate the central piston 32p of displacement unit 32 by directing the force (e.g., hydraulic pressure) from power source 34 to act on opposing chambers 31 and 33 of displacement unit 32. The system may include sensors 32s to detect, for example, the position (e.g., displacement) of piston 32p. Sensors 32s may comprise various types of sensors, gauges and devices and associated electronic systems.
Operation of the pumping system is described with reference to a “pump-up” operation depicted in
Log quality control (“LQC”) in prior art systems, such as depicted in
According to one or more aspects of the present disclosure, a pumpout system and method for improving the estimation of pumping flow rates (e.g., pumping times) particularly in gas environments, is addressed. Referring again to
Depicted tool 20 (
Referring to the graph of
The pressure effects across displacement unit 32 (e.g., chambers 31, 33) during a passive pumping system 100 operation are now described with reference in particular to
Flowing pressure (PFLOW) is depicted in
According to one or more aspects of the present disclosure, utilization of pump system 100 facilitates detecting or monitoring the closing, and opening, of mud valves CMV1-CMV4 via measurements of one or more of pressure gauges 50, 52, 54, 56, for example by comparing flowing pressures measured in the first and/or second flowlines 38a and/or 38b across the valve network 40 with pressure gauges 54 and/or 56 and pump chamber pressures measured in the pump chambers 31 and/or 33 with the pressure gauges 50 and or 52. The comparison may additionally involve the cracking pressure of mud valves CMV1-CMV4. Utilization of pump system 100 facilitate may also provide improved control and operation of tool 20. Although described in terms of discharging sample fluid to the wellbore, one skilled in the art will recognize use of the tool and system for pumping (e.g., drawing) fluid between different locations relative to displacement unit 32.
Proceeding along the operational path of displacement unit 32 the opening and closing of valves CMV1-CMV4 are depicted as the sampled fluid is drawn into displacement unit 32 by reciprocating the piston 32p and discharged from displacement unit 32. For example, displacement unit 32 has to overcome the hydrostatic pressure in the wellbore as well as the cracking pressure of valve(s) (e.g. CMV3) on the high pressure side (e.g., chamber 33 as piston 32p moves in displacement unit 32 to the left in
The detection of mud valve opening and/or closing by monitoring measurements of one or more of pressure gauges 50, 52, 54, 56 described herein may be more robust than monitoring the magnitude of the variation of a pump chamber pressure variations. For example, the variation of a pump chamber pressure may be large and the mud valves may be open to allow formation to flow in one pump chamber (for example when sampling formation fluid using the packer module 24). The large variation of a pump chamber pressure may alternatively indicate that the mud valves may be closed and that formation fluid is being compressed and/or decompressed in one pump chamber.
When one of the mud valve CMV1 or CMV2 partially fails (e.g., leaks), which is not an uncommon event, the pump system 100 may run in half stroking mode (i.e., only one of the chamber 31 or 33 may be pumping fluid in flowline 38). Thus, it may be useful to have two pump chamber pressure gauges 50 and 52 so that pumping monitoring may continue using the gauge monitoring the chamber that is still pumping fluid.
Monitoring of various pressures, as illustrated for example with reference to
The position of piston 32p may be identified as a function of time, for example, utilizing Hall Effect sensor data (e.g., sensors 32s), pump speed (e.g., rpm) data, etc. and/or as a function of displacement. Identifying no-flow phase data in combination with piston 32p position may facilitate determining the effective stroke of the piston. Knowledge of the effective stroke of piston 32p permits for more accurate determination of the fluid flow rate provided by displacement unit 32.
According to one or more aspects of the present disclosure, system 100 may be utilized to identify pressure losses due to friction and to locate a failure or problem in a particular mud valve (e.g., CMV1-CMV4) by monitoring pressures in chamber 31 and/or chamber 33 via gauges 50, 52, as well as other pressures via gauges 54, 56, and/or 36. Identifying the actual friction losses in the system may provide improved control and operation of tool 20. In some tools, identification of problems such as plugs and leaks in a particular mud valve may facilitate operating the tool 20 to direct fluid flow around identified problems and/or to correct a problem (e.g., back flowing to release a plug).
For example, a failure of a mud valve to close (e.g., leaking) may be resolved by inducting a high flow rate transient to dislodge the debris that may be preventing the complete closure of the leaking valve.
Pressure losses may be caused by accumulation of solid particles in the pump (e.g., dragging of the reciprocating piston 32p), and/or from viscosity affect across the valve network 40. Pressure losses through dragging of the reciprocating piston 32p may also be determined from pressure measurements at chambers 31 and/or 33 and 36. For example, a difference between the measured pump chamber pressures should normally be equal to the resultant pressure (PR) multiplied by a ratio. If not the case, this may indicate drag of the reciprocating piston 32p. If dragging of the reciprocating piston 32p is detected, operation of the pump system 100 may be stopped (e.g., before failure) or adjusted (e.g., pumping rate may be lowered to minimize production of solid particles from the formation). In contrast, pressure losses through valve network 40 may be determined from pressure measurements at chambers 31 and/or 33 and flowline 38. For example, a difference between a flow line pressure and a pump chamber pressure may be related to formation fluid viscous drag, which can be significant when pumping viscous formation fluids.
As described above, pump system 100 of tool 20 may be utilized for performing operations other than cleaning to obtain low contamination samples. For example, pump system 100 may be utilized to inflate packers 24a, over-pressurizing samples in sample containers 28a, performing mini-DST (e.g., miniature drill stem testing) and the like.
Inflation of packers 24a (
A method for drawing fluid from formation “F” and/or wellbore 2 and storing in sample chamber 28a (
According to one or more aspects of the present disclosure, tool 20 may be utilized for performing miniature drill stem testing operations, referred to as a mini-DST herein. Pumpout system 30 (e.g., displacement unit 32, valve network 40, flowlines, etc.) may be configured in and in/out mode (e.g., I/O port). The mini-DST may be performed by providing a time period of pressure drawdown followed by a time period of pressure build up utilizing displacement unit 32. Unexplained pressure noise can make it difficult or impossible to interpret data due in part to the low drawdown utilized, for example, pressure noise due to improper valve sealing (e.g., mud valves CMV1-CMV4), movement of the reciprocation of piston 32p, etc. Pump system 100 and tool 20 according to one or more aspects of the present disclosure provide means for addressing drawbacks of prior systems. For example, flowline gauges 54 and/or 56 positioned on opposite sides of the displacement unit 32 provide a means for detecting and indentifying noise.
For example, flowline noise close to packer module 24 may be detected and/or measured by gauge 54 (
Also, pressure gauges 50, 52, 54 and/or 56 may be used to distinguish mud valve improper sealing from piston movement during a DST test. A pressure disturbance that correlates between one of the flow line gauges 54 and/or 56 and one of the pump chamber gauges 50 and/or 52 may be indicative of improper mud valve sealing (e.g., mud valves CMV1-CMV4). A pressure disturbance that does not correlate between flow line gauges and pump chamber gauges may indicate mud valve proper sealing. A pressure disturbance that correlates between one of the pump chamber gauges (e.g., 50) and the other of the pump chamber gauges (e.g., 52) and/or with the gauge 36 may be indicative of piston movement. A pressure disturbance that does not correlate between one of the pump chamber gauges and the other of the pump chamber gauges may be indicative of absence of piston movement.
Mud valve network 40 may comprise passive and/or active mud valves (e.g., check valves, control valves).
Control of pump system 100 may be minimize and/or eliminate shocks to formation “F.” If a mud valve is opened to too early in the pumping cycle, fluid may flow from a pump chamber 31, 32 into formation “F” and if a mud valve is opened too late, formation “F” will see an abrupt pressure drop which may be undesirable. A method, according to one or more aspects of the present disclosure, for minimizing shocks at formation “F” is now described with reference in particular to
According to one or more aspects of the present disclosure, a system for pumping fluid at least partially through a downhole tool disposed in a wellbore comprises a displacement unit for pumping the fluid; a first flowline hydraulically connected to the displacement unit through a valve network for selectively communicating the fluid to or from the displacement unit; a second flowline hydraulically connected to the displacement unit through the valve network for selectively communicating the fluid to or from the displacement unit; a first chamber pressure gauge hydraulically coupled with a first chamber of the displacement unit; and a second chamber pressure gauge hydraulically coupled with a second chamber of the displacement unit.
The system may comprise a first flowline pressure gauge hydraulically coupled to the first flowline across the valve network from the displacement unit. The system may comprise a first flowline pressure gauge hydraulically coupled to the first flowline across the valve network from the displacement unit; and a second flowline pressure gauge hydraulically coupled to the second flowline across the valve network from the displacement unit and the first flowline pressure gauge.
According to one or more aspects the system may comprise a sample probe hydraulically coupled to the first flowline; and a fluid sample chamber hydraulically coupled to the second flowline. The system may further comprise a first flowline pressure gauge hydraulically coupled to the first flowline between the sample probe and the valve network. The system may still further comprise a second flowline pressure gauge hydraulically coupled to the second flowline between the fluid sample chamber and the valve network.
The system according to one or more aspects of the present disclosure comprises a power supply providing a force to operate the displacement unit; a force sensor measuring the force supplied to the displacement unit; a sample probe hydraulically coupled to the first flowline; an inflatable member hydraulically coupled to the first flowline; a first flowline pressure gauge hydraulically coupled to the first flowline between the sample probe and the valve network; and a fluid sample chamber hydraulically coupled to the second flowline.
A method according to one or more aspects of the present disclosure comprises disposing a tool in a wellbore, the tool comprising a displacement unit for pumping a fluid at least partially through the tool, a first flowline hydraulically connected to the displacement unit through a valve network, and a second flowline hydraulically connected to the displacement unit; pumping a fluid from the first flowline to the second flowline; monitoring a pressure at a chamber of the displacement unit; and monitoring flowing pressure in the first flowline across the valve network from the displacement unit.
The method may comprise discharging the fluid to the hydrostatic pressure in the wellbore. The method may comprise pumping the fluid into a container and ceasing pumping fluid into the container in response to the pressure monitored at the chamber of the displacement unit being about a rated pressure of the container. The method may comprise performing a drill stem test utilizing the tool.
The method may comprise performing a drill stem test utilizing the tool and identifying pressure noise in response to at least one of monitoring the flowing pressure in the first flowline and measuring the pressure at the chamber of the displacement unit.
The method may comprise inflating a packer element by pumping fluid into the packer element to achieve an inflate pressure; and checking achievement of the inflate pressure relative to the monitored pressure at the displacement unit.
The method may comprise monitoring a pressure at a first chamber of the displacement unit; monitoring a pressure at the second chamber of the displacement unit; monitoring a pressure in the first flowline across the valve network from the displacement unit; and monitoring a pressure in the second flowline across the valve network from the displacement unit and the first flowline. The method may comprise further comprise identifying the occurrence of no fluid flow from the displacement unit in response to at least one of monitoring the pressure of the first chamber and monitoring the pressure of the second chamber, and at least one of monitoring the pressure of the first flowline and monitoring the pressure of the second flowline. The method may further comprise determining the effective stroke of the piston in response to determining the occurrence of no fluid flow.
According to one or more aspects of the present disclosure, a method comprises disposing a formation testing tool in a wellbore, the tool comprising a displacement unit for pumping a fluid at least partially through the tool, a first flowline hydraulically connected to the displacement unit through a valve network, and a second flowline hydraulically connected to the displacement unit, wherein the valve network comprises at least a first active valve hydraulically connecting the first flowline to a first chamber of the displacement unit and a second active valve connecting the second flowline to a second chamber of the displacement unit; moving a piston of the displacement unit; monitoring the flowing pressure in the first flowline; monitoring the pressure in the low pressure chamber of the first chamber and the second chamber; and opening one of the first active valve and the second active valve in response to the pressure in the low pressure chamber being about equal to or less than the monitored flowing pressure.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.
This application is a continuation of U.S. patent application Ser. No. 12/619,101, filed Nov. 16, 2009, now U.S. Pat. No. 8,448,703, the entire disclosure of which is hereby incorporated by reference.
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Number | Date | Country | |
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Number | Date | Country | |
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Parent | 12619101 | Nov 2009 | US |
Child | 13901383 | US |