Patent Application
20100122812
Packers are used in wellbores to isolate specific wellbore regions. A packer is delivered downhole on a conveyance and expanded against the surrounding wellbore wall to isolate a region of the wellbore. Two or more packers can be used to isolate one or more regions in a variety of well related applications, including production applications, service applications and testing applications.
In some applications, straddle packers are used to isolate specific regions of the wellbore to allow collection of fluid samples. However, straddle packers employ a dual packer configuration in which fluids are collected between two separate packers. Existing designs often do not provide an operator with sufficient information regarding downhole parameters. Additionally, the straddle packer configuration is susceptible to mechanical stresses which limit the expansion ratio and the drawdown pressure differential that can be employed. Other multiple packer techniques can be expensive and present additional difficulties in collecting samples and managing fluid flow in the wellbore environment.
In general, the present invention provides a system and method for collecting formation fluids through a single packer having at least one drain located within the single packer. The single packer is designed with an outer flexible skin and one or more drains coupled to the outer flexible skin. The single packer further comprises one or more sensors positioned to detect one or more specific parameters.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention generally relates to a system and method for collecting formation fluids through one or more drains located in a packer, such as a single packer. Use of the single packer enables larger expansion ratios and higher drawdown pressure differentials. Additionally, the single packer configuration reduces the stresses otherwise incurred by the packer tool mandrel due to the differential pressures. In at least some embodiments, the single packer also is better able to support the formation in a produced zone at which formation fluids are collected. This quality facilitates relatively large amplitude draw-downs even in weak, unconsolidated formations.
The single packer expands across an expansion zone, and formation fluids can be collected from the middle of the expansion zone, i.e. between axial ends of the single packer. The formation fluid is collected and directed along flow lines, e.g. along flow tubes, from the one or more drains. For example, separate drains can be disposed along the length of the packer to establish collection intervals or zones that enable focused sampling at a plurality of collecting intervals, e.g. two or three collecting intervals. Separate flowlines can be connected to different drains, e.g. sampling drains and guard drains, to enable the collection of unique formation fluid samples.
The single packer provides a simplified packer structure that facilitates, for example, focused sampling. In one embodiment, one or more sensors are positioned along the single packer to monitor desired parameters. By way of example, the parameters may be related to well characteristics, including characteristics of flowing fluid, and/or to actuation of the single packer. In some applications, sensors can be incorporated into an outer flexible layer, e.g. an outer rubber layer. The outer flexible layer also may be used to contain drains, such as groups of drains in which a middle group comprises sampling drains and two axially outer groups comprise guard drains. The drains may be coupled to the flowlines in a manner that facilitates expansion and contraction of the single packer.
According to one embodiment, the present system and methodology generally relate to an instrumented packer assembly and methods for setting instrumentation into the packer assembly. The instrumentation may comprise one or more sensors designed to detect, measure and/or monitor downhole parameters. As described below, the sensors can be used with a single packer assembly to facilitate monitoring and operation of the packer assembly. The packer assembly, for example, enables placement of sensors to measure the packer expansion ratio and/or other measurements related to actuation of the packer. This allows for better control over operation of the packer. In some applications, measurements obtained downhole via packer sensors also can provide an indication of the level of stress applied to the packer. The sensors can further be used to measure well related parameters, such as fluid properties of fluids entering the packer during sampling procedures.
Referring generally to
In the example illustrated in
Data from the various sensors 40 is directed to a data acquisition system 44 which may be in the form of a computer based control system. With respect to the array off pressure sensors 42, the data acquisition system 44 may be employed to sample and store output from each sensor 42 during inflation of packer 24. The sensors may be numbered so the position of each sensor is known to the data acquisition system 44. As the output of each sensor 42 is sampled, the output is converted to contact pressure by data acquisition system 44. The local contact pressure is then compared to a global contact pressure predicted from the inflation pressure used to inflate packer 24. If one or more local pressure sensors 42 registers contact pressure that is significantly lower than the determined global contact pressure, an operator is better able to decide whether to move the entire packer 24 to a better position or to shut off one or more specific drains 30.
In an alternative approach, an average contact pressure based on data from local pressure sensors 42 can be determined. The average contact pressure is compared to the output of each sensor 42 to provide an indication of sealing integrity. The local contact pressures also can be used to prevent damage to the surrounding formation due to excessive pressure between the packer and the formation.
The plurality of sensors 40 also may comprise a variety of other types of sensors. For example, sensors 40 may comprise one or more extensometers 46 designed to detect and measure expansion of packer 24. Depending on the specific design of packer 24, the configuration of extensometers 46 can be selected to measure the expansion ratio of packer 24 via various techniques. By tracking expansion of packer 24, an operator is able to determine both the expansion ratio and whether the packer is or has been efficiently inflated. The sensors 46 also can be used to determine ovality and to control other operational parameters, such as ensuring full inflation while minimizing or optimizing inflation pressure. When sufficient pressure is applied to fully inflate packer 24, the extent of packer expansion can be measured by sensors 46 to determine whether full inflation has actually occurred. The extensometers 46 also may be used to provide measurements related to the deformation of outer flexible skin 26. Such information can be valuable in determining the integrity of or damage to inflatable packer 24. The information also can be valuable in determining the diameter of the outer flexible skin and thus the diameter of the borehole which is useful in providing job quality control, e.g. proper inflation, optimal tool selection, and washout detection. Data from extensometers 46 is delivered to data acquisition system 44 for appropriate processing.
In addition to the packer actuation sensors, e.g. sensors 42, 46, sensors 40 also may comprise sensors for measuring well related properties/characteristics. For example, sensors 40 may comprise one or more fluid property sensors 48, such as temperature sensors. When fluid property sensors 48 comprise temperature sensors, the temperature sensors can be used within packer 24 for quality control. For example, temperature sensors 48 are useful in very low or very high temperature wells in which the properties of the outer flexible skin 26 are affected and can inhibit optimal operation of packer 24. For example, temperature can affect the ability of outer flexible skin 26 to form adequate seals, and temperature also can render the outer flexible skin more sensitive to extrusion and deformation and thus a decreased lifetime. If the information is obtained and relayed from sensors 48 to data acquisition system 44, the information can be used to predict the number of stations at which inflatable packer 24 is likely to perform in the given conditions.
The fluid property sensors 48 may be located within one or more of the sampling drains 32 and guard drains 34. In some applications, for example, fluid property sensors 48 comprise formation pressure sensors installed within each sample drain 32 and guard drain 34. By way of example, the formation pressure sensors may be mounted on an opposite side of the flow line 36 for each sample drain and may be mounted perpendicular to the flow line 36 for each guard drain.
When fluid property sensors 48 comprise pressure sensors within each drain 30, the sensors 48 may be used for a variety of purposes. For example, the sensors 48 may be used to detect leaks and/or plugging prior to formation testing measurements. When formation pressure sensors are used to monitor for leaks, the output from each sensor 48 can be compared to the wellbore pressure. In the event pressure is registered by sensors 48 as on par with the wellbore pressure during a drawdown, an operator is able to determine that either the sealing has been compromised or a flow line 36 is plugged. Also, if the pressure sensors 48 have sufficiently high resolution, individual sensors can be used to take pretest measurements in the formation and can further be used in performing transient pressure build up measurements. However, application of these various techniques depends on the degree of isolation with respect to guard drains and sample drains.
Fluid property sensors 48 may be positioned within drains 30 or at other suitable locations, such as within flow lines 36 and/or in collectors at the axial ends of packer 24. The fluid property sensors are extremely useful in providing direct measurements of fluid properties close to the formation. For example, sensors 48 can be used to measure temperature, viscosity, velocity, pressure, or other fluid parameters at each drain 30. The data enables numerous evaluations, including verification of sealing by detecting clean/dirty fluid. The data also can provide an indication as to whether flow lines are plugged, leaking, or incurring other types of problems.
In many applications, sensors 40 also may comprise one or more pressure gauges 50 deployed in flow lines 36. Additionally, sensors 40 may comprise one or more sensor cells 52 positioned at suitable locations, e.g. within flow lines 36, to measure density, resistivity, viscosity, and other parameters of the fluid flowing into packer 24. Resistivity measurements can be used for obtaining data related to clean-up time and sample assurance during a sampling operation. Additionally, sensors 40 may comprise one or more flow meters 54 that can be used to measure flow rates within flow lines 36 or at other locations within packer 24.
The sensors 40 may be positioned at a variety of locations depending on the parameters measured and depending on the durability of the sensor. For example, sensors can be located within collectors at the end of the packer instead of in drains 30 to improve reliability. Additionally, sensors can be mounted in front of each flow line entrance for individual measurements or inside flow line collectors to obtain average measurements.
By positioning one or more sensors 40 on and/or in inflatable packer 24, the sensors are useful for detecting many operational parameters. For example, the sensors 40 can be used individually or in cooperation to detect packer inflation, an opening of a first flow line 36, a drawdown pressure initiated, an opening of a subsequent flow line, an occurrence of a leak, a shut down of flow lines upon leak detection, selected fluid properties, and a variety of other parameters and operational events.
Control over flow through individual flow lines 36 can be achieved by placing valves 56 in desired flow lines 36. The valves 56 are used to open or shut down individual flow lines upon the occurrence of specific events, such as leakage proximate a given drain 30. The control system/data acquisition system 44 also can be designed to exercise control over the opening and closing of valves 56.
Referring generally to
Once the inflatable packer 24 is properly positioned in the wellbore and sufficient sealing is verified, the sampling procedure begins, as illustrated by block 68. During the sampling procedure, the fluid properties and drain sealing may be monitored by appropriate sensors 40, as illustrated by block 70. Subsequently, the sampling procedure is completed, as indicated by block 72, and the packer 24 is deflated, as indicated by block 74. The sensors 40, e.g. extensometers 46, can again provide data to data acquisition system 44 to verify packer deflation, as indicated by block 76. Upon deflation, the packer 24 may be moved to the next sampling location, and the procedure may be repeated.
Depending on the specific application and environment, various procedural steps can be added, removed, and/or expanded. Furthermore, data acquisition system 44 can be programmed to utilize sensor data according to a variety of paradigms. As illustrated in
Similarly, the procedural stage involving completion of inflation and monitoring of contact pressure also may utilize output from various sensors 40, as illustrated by the flowchart of
The verification of sealing with respect to individual sample drains and guard drains also may comprise additional procedural steps and utilization of sensor data, as illustrated by the flowchart of
If the seal integrity is sufficient, the sealing verification stages are repeated for each of the remaining drains, as indicated by block 108, until the verification process is completed and the overall sampling process can be moved to the next stage, as indicated by block 110. If the seal integrity of a given drain is not sufficient, the inflation pressure of packer 24 can be increased to a maximum working pressure, as indicated by block 112. Assuming the increased pressure results in sufficient seal integrity, the stages can be repeated for the other drains. However, if the action does not result in sufficient seal integrity additional corrective action can be taken, as indicated by block 114. For example, the packer 24 can be reinflated at a different location or one or more of the drains 30 can be mechanically isolated.
The monitoring of fluid properties and drain sealing following initiation of the sampling procedure also may comprise additional procedural steps and utilization of sensor data, as illustrated by the flowchart of
Once the seal integrity for each of the drains is addressed, the fluid flow rate through each drain is detected by an appropriate sensor 40, e.g. flow meter 54, as indicated by block 124. If the flow rate is sufficient for the drains, the fluid properties from the fluid collected through each drain are monitored, as indicated by block 126. However, if the flow rate data indicates a clogged drain, the drain can be isolated by closing the associated valve 56, as indicated by block 128. In the event a clogged drain is corrected, the monitoring of fluid properties for the drain can be commenced once again. However, if the drain is not unclogged additional corrective action may be taken, as indicated by block 130. For example, the packer 24 can be deflated and fluid can be reversed pumped through the packer to clear the drain obstruction.
After the flow rates for the drains are addressed, the fluid resistivity can be checked for each sample drain 32 via, for example, resistivity sensors 52, as indicated by block 132. If the resistivity is indicative of the desired fluid flow, the pumping of sample fluid is continued until the sampling operation is completed, as indicated by block 134. Subsequently, the overall sampling process may be moved to the next stage, as indicated by block 136. In the event the resistivity data indicates the presence of an unwanted fluid, such as water, corrective action may be taken, as indicated by block 138. For example, the sample drain producing water can be isolated by adjusting the appropriate valve.
The verification of packer deflation upon completion of a sampling procedure also may comprise additional procedural steps and utilization of sensor data, as illustrated by the flowchart of
The procedural examples illustrated and described above are just a few of the many procedural approaches that can be used in utilizing sensor system 38 and in obtaining fluid samples with single packer 24 in a variety of well environments. Similarly, the size, shape and configuration of packer 24 may vary depending on the specific sampling applications and environments.
One embodiment of a specific single packer design is illustrated in
With additional reference to
As illustrated in
Referring generally to
In this particular embodiment of inflatable packer 24, extensometers 46 are designed as rotational sensors positioned to engage and measure rotation of select movable members 154. (See
The expansion ratio of the packer also is useful in providing a more accurate measurement of the borehole dimensions and its irregularities that can result from washouts and/or distorted ovality. The packer can effectively be used as a caliper tool which also is helpful in evaluating the wellbore. For example, by obtaining data on well ovalization, packer pressurization can be optimized to ensure sealing. In some types of packers, e.g. cable packers, the packer can experience weakening when inflated in oval wells. Consequently, data collected on wellbore ovalization is useful in ensuring that inflation pressure does not break an inner bladder of the packer. The measurement of packer outside diameter also is useful when the packer 24 is deflated. By knowing the degree of deflation, an operator can determine whether extraction of the packer is possible and whether retraction mechanisms, e.g. auto retract mechanisms, are operating efficiently.
As illustrated in
Furthermore, valves 56 may be mounted in desired locations along flow lines 36, as illustrated in the example of
The sensors 40 provide an instrumented packer 24 that may be selectively expanded, e.g. inflated, in a wellbore, as illustrated by
Also, in any of the embodiments described above where a component is described as being formed of rubber or comprising rubber, the rubber may include an oil resistant rubber, such as NBR (Nitrile Butadiene Rubber), HNBR (Hydrogenated Nitrile Butadiene Rubber) and/or FKM (Fluoroelastomers). In a specific example, the rubber may be a high percentage acrylonytrile HNBR rubber, such as an HNBR rubber having a percentage of acrylonytrile in the range of approximately 21 to approximately 49%. Components suitable for the rubbers described in this paragraph include, but are not limited to, outer flexible skin 26 and inflatable bladder 148.
As described above, packer assembly 20 may be constructed in a variety of configurations for use in many environments and applications. The packer 24 may be constructed from different types of materials and components for collection of formation fluids from single or multiple intervals within a single expansion zone. The flexibility of the outer flexible skin enables use of packer 24 in many well environments. Additionally, the various sensors and sensor arrangements may be used to detect and monitor many types of parameters that facilitate numerous procedures related to the overall sampling operation. Furthermore, the various packer components can be constructed from a variety of materials and in a variety of configurations as desired for specific applications and environments.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/116,442, filed on Nov. 20, 2008, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61116442 | Nov 2008 | US |
