Patent Application
20140116718
None.
The present disclosure generally relates to evaluation of a subterranean formation. More specifically, the present disclosure relates to a packer tool with a sealing layer.
For oil and gas exploration, information about subsurface formations that are penetrated by a wellbore is necessary. Measurements are essential to predicting production capacity and production lifetime of a subsurface formation. Collection and sampling of underground fluids contained in subterranean formations are well known. Moreover, testing of a formation may provide valuable information regarding the properties of the formation and/or the hydrocarbons associated therewith. In the petroleum exploration and recovery industries, for example, samples of formation fluids are collected and analyzed for various purposes, such as to determine the existence, composition and producibility of subterranean hydrocarbon fluid reservoirs. This aspect of the exploration and recovery process is crucial to develop exploitation strategies and impacts significant financial expenditures and savings.
A variety of packers are used in wellbores to isolate specific wellbore regions. A packer is delivered downhole on a tubing string, and a packer sealing element is expanded against the surrounding wellbore wall to isolate a region of the wellbore. The sealing layer of the sealing element is typically a uniformly-surface, cylindrical layer of rubber/elastomer. Often, two or more packers may be used to isolate several regions in a variety of well related applications, including production applications, service applications and testing applications.
Isolating a particular section of a wellbore typically involves deploying a dual packer system. Deploying a dual packer system is more involved than deploying a single packer since a greater likelihood that one packer may fail exists. Therefore, a single packer is desired which may be deployed in a formation to isolate a portion of the wellbore.
Certain examples are shown in the above-identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness.
Aspects generally relate to a system and method for collecting formation fluids using a single packer with rings and/or an irregular sealing layer. Use of the single packer with rings 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 may support the formation in hydrocarbon-yielding zone at which formation fluids are collected. The single packer configuration 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 bowlines 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. The outer flexible layer may also be used to contain drains, such as groups of drains in which a middle group has sampling drains and two axially outer groups have guard drains. The drains may be coupled to the bowlines in a manner that facilitates expansion and contraction of the single packer.
Referring now to
The packer 24 is a single packer having an outer layer formed of an outer flexible skin 26 made from an elastic material, e.g. rubber. The outer flexible skin 26 is expandable in a wellbore to seal with a surrounding wellbore wall. The single packer 24 has an inner inflatable bladder 148 disposed within the outer flexible skin 26. By way of example, the inner bladder 148 may be selectively expanded by introducing fluid via the interior packer mandrel 28. Additionally, the packer 24 has a pair of mechanical fittings 150 that may have fluid collectors 152 coupled with the flow lines 36. The mechanical fittings 150 are mounted around the inner mandrel 28 and engaged with axial ends of the outer flexible skin 26.
Referring to
As illustrated in
As described above, the 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 26 enables use of the packer 24 in many well environments. 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.
The rings 40, 42 may isolate different portions of the wellbore during testing. Thus, the rings 40, 42 may be used for focused sampling of specific portions of a wellbore. That is, the packer 100 may be disposed in a wellbore at any depth to test a particular section of that wellbore. Moreover, the rings 40, 42 may enable sampling across a larger surface area. For example, the rings 40, 42 may isolate an entire section of the wellbore. Fluid drawn into the sample drains 32 may be extracted from the entire isolated portion. Thus, the rings 40, 42 enable any size or type of drain to be used. For example, if a small drain is used, a sufficient amount of fluid may be sampled due to the isolation of an entire section of the wellbore using the rings 40, 42.
Further, the rings 40, 42 may improve fluid sampling in tight formations. The rings 40, 42 may create an air-tight seal in the isolated portion of the wellbore. Thus, the packer 100 may create a larger pressure differential to draw fluid from the tight formation. The outer rings 42 isolating the guard drains 134 may focus contaminated fluid into the guard drains 134. Thus, the segregation of non-contaminated fluid and contaminated fluid may be more effectively implemented.
The rings 40, 42 may be provided with the packer 100 and/or may be retrofitted to the packer 100. The rings 40, 42 may be installed and/or removed depending on the formation and/or the desired sampling method. The rings 40, 42 may be permanently affixed to the packer 100 by welding, fasteners, and/or cement. The placement of the rings 40, 42 may also be customized depending on a desired application. For example, in a formation with increased contaminants in the fluid, a larger guard drain section may be desired.
In the illustrated embodiment, the packer 100 has four rings: two inner rings 40 and two outer rings 42. The rings 40, 42 define three contiguous sections 51, 52, 53. The first section 51 and the third section 53 may contain guard drains 134. The second section 52 may contain sample drains 132.
When deployed and expanded in a wellbore 19, the three sections 51, 52, 53 may enclose three corresponding sections of the wellbore. The rings 40, 42 create a temporary seal between the packer 100 and walls 17 of the wellbore. A pressure differential may be initiated in the packer 100 to draw fluid from the formation 23 into the drains 132, 134.
In practice, when the packer 100 is expanded to abut the walls 17 of the wellbore 19, the outer diameter of the packer 100 is flush against the wall of the wellbore 19. Without the grooves 44, fluid may only be drawn into the drains 132, 134 from that portion of the wall 17 that is directly abutted to the drain 132, 134. However, the grooves 44 create leak paths through which sample fluid may flow. The leak paths formed by the grooves 44 may carry fluid to one or more of the drains 132, 134.
In
In the embodiments described above where a component is described as 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, the outer flexible skin 26 and the inflatable bladder 148.
In one embodiment a system for collecting fluid in a wellbore is disclosed comprising an outer flexible skin having an outer diameter, a plurality of rings disposed around the outer diameter, a plurality of drains coupled to the outer flexible skin, and a mandrel positioned within the outer flexible skin. In another embodiment, a method is disclosed comprising deploying a packer assembly into a wellbore wherein the packer assembly inflates toward a wall of the wellbore and has an opening connected to a flow line for receiving fluid and two exterior rings extending around a circumference of the packer assembly; expanding the packer assembly such that the exterior rings abut the wall of the wellbore; isolating a section of the wellbore by creating a seal between the wellbore wall and the exterior rings and obtaining fluid through the opening. In still another embodiment, a sampling tool is disclosed comprising an outer sealing layer having irregularities, a plurality of drains coupled to the outer sealing layer, a flow line connected to an opening for moving the fluid into the packer assembly, and a mandrel positioned within the outer flexible skin.
Although exemplary systems and methods are described in language specific to structural features and/or methodological acts, the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed systems, methods, and structures. 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 above.
