Patent Application
20130306309
A variety of 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. Often, 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, a straddle packer can be used to isolate a specific region of the wellbore to allow collection of fluid samples. However, straddle packers use a dual packer configuration in which fluids are collected between two separate packers. The dual 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 structural layer that expands across an expansion zone to facilitate creation of a seal with a surrounding wellbore wall. An inflatable bladder can be disposed within the outer structural layer to cause expansion, and a seal can be disposed for cooperation with the outer structural layer to facilitate sealing engagement with the surrounding wellbore wall. One or more drain features are used to improve the sampling process and/or to facilitate flow through the drain over the life of the single packer.
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 a drain located in a single packer. The collected formation fluids are conveyed along an outer structural layer of the packer to a flow line and then directed to a desired collection location. 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 some embodiments, the packer uses a single expandable sealing element which renders the packer 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 outer sealing layer. The formation fluid collected is directed along flow lines, e.g. along flow tubes, having sufficient inner diameter to allow operations in relatively heavy mud. Formation fluid can be collected through 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 incorporates or cooperates with a variety of features to improve efficiency of the sampling operation and to facilitate flow through packer drains over the life of the single packer. For example, the single packer may incorporate surrounding edges arranged around the drains to prevent extrusion of a seal layer. Additionally, individual seal members may be mounted around each drain, or an overall seal layer can be constructed with passages to enable fluid communication between specific groups of drains. The configuration of the single packer also enables cleaning of wellbore regions by creating inward or outward fluid flows through the drains to remove material that would otherwise interfere with well fluid in sampling operations. A variety of other features can be incorporated into the single packer to facilitate a variety of sampling operations, to make the packer more reliable and more efficient, and to enhance the life of the packer.
Referring generally to
Referring generally to
Outer structural layer 40 may comprise one or more drains 50 through which formation fluid is collected when outer layer 40 is expanded to seal the single packer 26 against surrounding wellbore wall 32. Drains 50 may be embedded radially into a sealing element or seal layer 52 that surrounds outer structural layer 40. By way of example, sealing layer 52 may be cylindrical and formed of an elastomeric material selected for hydrocarbon based applications, such as a rubber material.
A plurality of tubular members or tubes 54 can be operatively coupled with drains 50 for directing the collected formation fluid in an axial direction to one or both of the mechanical fittings 46. In one example, alternating tubes 54 are connected either to a central drain or drains, e.g. sampling drains 56, or to axially outer drains, e.g. guard drains 58, located on both axial sides of the middle sampling drains. The guard drains 58 can be located around the sampling drains 56 to achieve faster fluid cleaning during sampling. As further illustrated in
Referring generally to
In the embodiment illustrated, a plurality of movable members 68 are pivotably mounted to each collector portion 62. At least some of the movable members 68 are designed as flow members that allow fluid flow between tubes 54 and collector portions 62. Certain movable flow members 68 can be coupled to tubes 54 extending to sampling drains 56, while other movable flow members 68 can be coupled to tubes 54 extending to guard drains 58 to enable separation of guard drain flow and sampling drain flow. In this example, movable flow members 68 are generally S-shaped and designed for pivotable connection with both the corresponding collector portion 62 and the corresponding tubes 54. As a result, members 68 can be pivoted between the contracted configuration illustrated in
Referring generally to
Individual drains may comprise or cooperate with a drain feature 72 designed to enhance sampling efficiency and to facilitate flow through the corresponding drain over the life of the single packer 26. The drain features 72 may be utilized at all drains 50 or at selected drains. By way of example, drain feature 72 may comprise a surrounding edge 74 arranged around each drain 50 to prevent extrusion of seal layer 52 between the drain and the wellbore wall, as illustrated in
Another embodiment of drain feature 72 is illustrated in
Referring generally to
As illustrated in
The guard drain flow system 86 similarly comprises a guard drain flow line 104 connected to the guard drains 58. The flow line 104 extends from guard drains 58 to a flow line outlet 106 on an opposite side of pump 90. A valve 108 is positioned in flow line 104 between pump 90 and outlet 106. Optional valves 110 also may be positioned in flow system 86 proximate each guard drain 58 to enable isolation of individual guard drains. In the embodiment illustrated, a crossover flow line 112 also is connected between guard drain flow system 86 and sampling drain flow system 84 to allow continued fluid sampling procedures in the event flow line 92 fails to function properly. In this latter scenario, the fluid samples can be collected through flowlines 104. Crossover flow line 112 can be coupled with guard drain flow system 86 via valve 108 and with sampling drain flow system 84 between valves 98 and 100.
A variety of procedures can be performed via single packer 26 in cooperation with flow systems 84 and 86 by operating the pumps and valves in selected operational states. Some examples of procedures/operational phases of a sampling operation are provided as follows:
Additionally, the isolation valves 102, 110 can be operated to selectively isolate sampling drains 56 and/or guard drains 58 if necessary. For example, a given sampling operation can be initiated by successively opening each drain 56, 58 and recording the pressure response of the single packer 26. If a substantial pressure increase occurs after the opening of an individual drain, a leak is indicated and the specific drain can be closed or isolated via the appropriate isolation valves 102 or 110. The sampling operation can then be continued with the remaining operational drains.
An alternate embodiment is illustrated in
The embodiment illustrated in
In some applications, single packer 26 incorporates filtering mechanisms to filter solids, such as mud/sand or other particulates from the incoming well fluid. As illustrated in
In many applications, the single packer 26 can be used to clean regions of wellbore 22 by flushing well fluid through the drains 50. In one embodiment, the cleaning is performed prior to sampling of the fluid. This allows for the performance a fluid analysis, while reducing the risk of plugging filters. As illustrated in
Alternatively, flushing fluid can be delivered through one flow system and removed through another, as illustrated in
In some applications, sampling efficiency can be improved by creating an initial pressure drawdown to break the mudcake for removal prior to sampling. As illustrated in
Single packer 26 also can be constructed with portions 140 of flowlines embedded in outer seal layer 52 to facilitate pressure equalization after inflation of the packer, as illustrated in
As described above, well system 20 may be constructed in a variety of configurations for use in many environments and applications. The single packer 26 may be constructed from a variety of materials and components for collection of formation fluids from single or multiple intervals within a single expansion zone. The ability to expand a sealing element across the entire expansion zone enables use of packer 26 in a wide variety of well in environments, including those having weak unconsolidated formations. The various drain features and flow system arrangements also can be constructed in several arrangements to provide a more reliable and efficient single packer design.
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, inner inflatable bladder 42, sealing layer 52, and individual seal(s) 78.
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.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12234107 | Sep 2008 | US |
| Child | 13948565 | US |
