BR102012032901A2 - METHOD FOR OBSERVING AN UNDERGROUND HOLE, METHOD FOR OBSERVING AN ANNULAR SPACE, METHOD FOR ANALYZING ANNULAR SPACE AND METHOD FOR MONITORING AN UNDERGROUND FILL - Google Patents

Abstract

METHOD FOR OBSERVING AN UNDERGROUND HOLE, METHOD FOR OBSERVING AN ANNULAR SPACE, METHOD FOR ANALYZING ANNULAR SPACE AND METHOD FOR MONITORING AN UNDERGROUND FILL. The present invention relates to dispersed gamma ray monitoring and is used to identify substances disposed between coaxial tubes 412 disposed in an underground bore 402. Gamma rays are strategically directed from the interior of an innermost tube 412 to the interior of the annular space 422 and some of the gamma rays scatter from the substance between the tube 412s and are detected with detectors set at a designated axial distance from the gamma ray source 428. Gamma rays also disperse from the fluid in the Inside tube 412, a ratio of the detected gamma rays scattering from the fluid in tube 412 and from the substance can be used to determine the substance.

Description

“METHOD FOR OBSERVING AN UNDERGROUND HOLE, METHOD FOR OBSERVING AN ANNULAR SPACE, METHOD FOR ANALYZING ANNULAR SPACE AND METHOD FOR MONITORING A FILL WITH

UNDERGROUND GRAVEL ”

Cross Reference to Related Requests

This patent application is a partial continuation and claims the benefit of copending patent application No. US 12 / 496,163 filed July 1, 2009, the full disclosure of which is incorporated by reference herein.

Background

1. Field of the Invention The invention generally relates to the discovery of an annular space between the pipes disposed in an underground bore. More specifically, the present invention relates to a device and method using a radiation source to ascertain an underground annular space and a radiation detector to identify a substance or substances in the annular space.

2. Description of the Prior Art Underground holes used to produce hydrocarbons are typically aligned with a compartment column that is cemented in cross-hole formation. Often an internal housing column is inserted into the cemented compartment column at the location. The fluid produced from the well flows to the surface inside the production pipe that is inserted inside the inner housing column. During the life of a typical well the production piping can be removed so that repair, repair, or flow enhancement operations can be initiated in the well. There may also be a need at some point for removal of a portion or for the entire compartment.

Generally drilling fluids fill the annular space between the concentric tubes. Particulate matter within drilling fluids may settle or precipitate over time to form a cement-like substance that mates with the concentric tubes and prevents removal of the inner tube from the hole. Although 5 cutting tools can cut the tubes to allow removal of the unobstructed portion, the tube cannot be removed if the cut is made to a depth below which the tubes are attached to each other. Alternatively, a very shallow cut may leave an undesirably long portion of the free barrel extending above the point of adhesion.

Brief Description of the Invention

A method for finding an underground bore is provided herein. In one example the method includes generating radiation from inside a pipe that is disposed in the underground bore. The radiation is directed along a path that is oblique to a geometrical axis of the tube allowing a portion of the radiation to pass through the tube into an annular space surrounding the tube and dispersing back into the tube. pipe. A portion of the radiation dispersing back into the tube is detected and a detected radiation count is used to identify a material in the annular space. Alternatively, radiation is a first set of radiation and the trajectory is a first trajectory. In this example the method further includes directing a second set of radiation along a second path that moves away from the first path. A portion of the second radiation array disperses from the fluid disposed in the tube and is detected. Thus, in an exemplary embodiment, identifying a material in annular space is additionally based on a detection rate of the second set of radiation. The radiation may be a gamma ray from a gamma ray source having an energy of about 250 keV to about 700 keV. In this example, the scattered radiation when detected has an energy of about 50 keV to about 350 keV. In an alternative embodiment the method may also include detecting a substantially solid material in annular space when a ratio of the detection rate of the first set of radiation above the detection rate of the second set of radiation remains substantially the same with changes in thickness. In one example, the material in the annular space is a lightweight cement.

Also included herein is a method for ascertaining an annular space between coaxially disposed inner and outer tubes including providing a gamma ray source against an azimuthal section of the inner tube. The method also includes directing the gamma rays from the source so that some of the gamma rays move into the annular space and disperse from a material in the annular space back into the inner tube. In this example, some of the gamma rays move away from the azimuthal section and disperse from a fluid in the inner tube. Gamma rays that disperse back can be detected, the method may also include sorting by energy range gamma rays that disperse from the fluid in the inner tube and disperse from the material in the annular space and identify the material. in the annular space based on a scattered gamma ray detection rate. In an alternative, a conically shaped guide is provided near the gamma ray source and positioned so that a guide hole is directed toward the source and the guide has a geometry axis that is substantially parallel to a geometry axis of the inner tube. The detector 25 may be arranged from about 5.08 cm (2 inches) to about 10.16 cm (4 inches) from the gamma ray source and wherein the detector is used to detect scattered gamma rays. In one example, a collimator is used to strategically direct gamma rays away from the source at an oblique angle to a geometry axis of the inner tube and along distinct paths arranged azimutally around the gamma ray source, so that strategically located detectors, respectively, detect dispersion from distinct azimuthal areas spaced radially outward from the gamma ray source. Optionally, a gamma ray detection rate dispersion from the fluid in the hole is used as a reference for determining material in annular space. The generate and detect steps can be repeated at different depths in a section of the hole. A substantially solid material in the annular space can be identified when a ratio of a detected gamma ray rate that is dispersed from the annular space above a detected gamma ray rate that is dispersed from the fluid in the inner tube remains substantially same with changes in annular space thickness. Optionally, a fluid may be identified in the annular space when a gamma ray rate detection ratio 15 reduces with a reduction in annular space thickness.

A method for analyzing an annular space between an inner tube and an outer tube that is coaxially arranged in an underground bore is provided herein which includes providing a gamma ray source 20 against an azimuthal section of the inner tube and directing the radii. from the source so that some of the gamma rays move through the sidewall into the annular space and disperse from a material in the annular space back into the inner tube and so that some of the Gamma rays move away from the azimuthal section and disperse from a fluid in the inner tube. In this example, dispersed gamma rays are detected and disperse from the fluid in the inner tube and which disperse from the material in the annular space and are classified. Material in annular space is identified based on a scattered gamma ray detection rate. The steps of this method can be repeated at different depths in a section of the hole and a substantially solid material identified in annular space when a ratio of a detected gamma ray rate is scattered from space.

Annularity above a rate of detected gamma rays that are dispersed from the fluid in the inner tube remains substantially the same with changes in annular space thickness. A substantially liquid material is identified in the annular space when a ratio of a detected gamma ray rate that is scattered from the annular space above a detected gamma ray rate that is scattered from the fluid in the inner tube is reduced. with a reduction in annular space thickness. In an alternative, the rate of detection of gamma rays that are dispersed from the fluid in the tube is a reference value for use in identifying a liquid in annular space.

Brief Description of the Figures

Some of the features and benefits of the present invention have been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic of an exemplary embodiment of a downhole imaging tool having a low energy radiation source and detectors disposed in a bore according to the present invention.

Figure 2 is a perspective view of one embodiment of the tool of Figure 1.

Figures 3A and 3B are sectional views of one embodiment.

example of the tool in Figure 2.

Figure 4 is an example of a graph representing a source response in a gravel fill for baritin curvature detection.

Figure 5 is a graph of a count rate versus depth measured by an exemplary embodiment of an imaging tool in accordance with the present invention.

Figure 6 is a side sectional view of one embodiment

Alternative example of the tool of Figure 1 disposed in a coated hole according to the present invention.

Figure 7 is a side sectional view of a portion of Figure

6 shown with additional details.

Figure 8A is a side sectional view of the tool and hole.

of Figure 7.

Figure 8B is a side sectional view of the tool and hole of Figure 8A.

Figure 9A is a side sectional view of the tool and bore of Figure 7 with the production piping asymmetrically disposed within a housing column.

Figure 9B is a side sectional view of the tool and hole of Figure 9A.

Figure 10 is a graphical representation of changes in annular space thickness between concentric downhole tubes and gamma ray count rates reflected from materials in annular space.

Figure 11 is a graphical representation of changes in annular space thickness between concentric downhole tubes and a measured gamma ray response shifted from materials in annular space.

Figure 12A is a partial partial sectional view of an example of a bore imaging tool that takes a baseline image of a gravel filler in accordance with the present invention.

Figure 12B is a partial side sectional view of the tool of Figure 12A illustrating the gravel fill at a time after that of Figure 12A in accordance with the present invention.

Figure 12C is a partial side sectional view of an example of an imaging tool illustrating a gravel filler following a gravel filler repair step in accordance with the present invention.

Figure 13 is a partial side cross-sectional view of a

An exemplary embodiment of an imaging tool that illustrates a housing connection according to the present invention.

Figure 14 is a partial partial sectional view of an exemplary embodiment of an asphaltenes imaging tool in a gravel filler in accordance with the present invention.

Figure 15 is a partial side sectional view of an alternative embodiment of the imaging tool of Figure 6 shown substantially centered in a hole.

Although the invention is described in connection with the embodiments

Preferred, it will be understood that this description is not intended to limit the invention to the embodiment. Rather, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Detailed Description of the Invention

The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; on the contrary, these achievements are provided so that this presentation will be perfect and complete and will fully carry its scope to those skilled in the art. Similar numbers refer to similar elements throughout this document.

It should further be understood that the scope of this presentation is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, modifications and equivalents will be apparent to one skilled in the art. In the drawings and descriptive report there may be illustrative embodiments presented and although specific terms are employed, they may be used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the improvements described herein should therefore be limited only by the scope of the appended claims.

Referring now to Figure 1, a downhole imaging tool 100 is shown positioned on a "base pipe" or internal steel housing 110 of a gravel filler. It is recognized 20 that a tool housing 130 may be constructed from any light metal wherein the term "light metal" as used herein refers to any metal having an atomic number less than 23. The downhole imaging tool 100 includes at least one housing or barrel 130 carrying a low energy radiation source 120 and a plurality of detectors 140. In an exemplary embodiment, the gamma radiation source 120 is centrally located. optionally, detectors 140 are symmetrically spaced from each other azimuthally at a constant radius, but also positioned within housing 130. In other words, in one example, the radius at which detectors 140 are spaced from each other others is smaller than the radius of housing 130. Radiation source 120 emits radiation, in this case gamma rays 124 in the gravel filler 150.

Alternate hatch of gravel filler 150 indicates

possible gravel filler regions that could be filled with gravel or not. For example, the central region 151 may constitute a vacuum in the gravel filler 150 that has been filled with finishing fluids or production fluids through which other regions 153 may constitute portions of the gravel filler which are which are completed or filled appropriately. Of course, those skilled in the art, for the benefit of the present disclosure, will appreciate that the above regions are for illustrative purposes only and that a vacuum or pocket can have any shape and any position relative to tool 100.

In the example in Figure 1, gamma rays 124 that propagate

into the gravel filler 150 are dispersed by Compton (as in point 155), with some energy lost, back toward the detectors 140 located within the downhole imaging tool 100. By gamma ray scattering , they become lower energy gamma rays 126, which are detected by detectors 140. The intensity of the gamma ray count rate dispersed by Compton 126 depends on, among other factors, the density of the gravel filler. Thus, higher counting rates represent higher gravel fill density, where lower counting rates 25 represent lower density as a result of fewer gamma rays being scattered back toward the detectors.

In one example, radiation source 120 includes barium, cesium, some other low energy radiation source, or combinations thereof. By using such a low power source, the energy is propagated only a short distance into the gravel filler immediately adjacent to a screen. For the same reason, in one example, detectors 140 are positioned in housing 130 next to radiation source 120. In an exemplary embodiment, radiation source 120 and detectors 140 are within about 7.62 cm ( 3 inches) about 3.5 inches (8.89 cm) along the tool length 100.

The shield (not shown in Figure 1) may be applied around radiation source 120 to collimate or otherwise limit radiation emission from radiation source 120 to a limited longitudinal gravel filler segment 150. In one embodiment, such a shield is a heavy metal shield, such as sintered tungsten, which collimates the pathway to the gamma rays emitted into the gravel filler. Similarly, as described in more detail below, similar shielding may be used around each detector to limit the detector viewer hole to only gamma rays that are mainly uniquely dispersed back to the detector from a specific azimuthal section of the gravel filler.

In addition, the energy levels of the gamma rays emitted 124

can be selected to evaluate gravel fill density at varying depths or distances from wellbore imaging tool 100. As an example, radiation from a low energy gamma ray source such as a source 133Ba, can be used to emit various levels of energy. Alternatively, a gamma radiation source with energy close to 137 Cs may be used.

Techniques for converting radiation count rates to a full 2D profiled map of gravel fill integrity include the 3D method curve of the SYSTAT table. Other techniques include, but are not limited to, MATLAB, IMAGE, and advanced logging and techniques for fabricating mosaic representations from data points can be used to map the base pipe and the environment of the 5-gravel filler. Also, 3D geostatistics-based software can be adapted to convert basic gamma ray count rates to generate a map of the gravel fill environment. In this way, the integrity of a gravel filler or formation can be determined.

To produce precisely oriented maps, the angle

The azimuthal profile of the profiling tool in relation to the raised side of the wellbore is determined. This orientation may be determined using any guidance device known in the art. Guidance devices may contain one or more orientation sensors used to determine the orientation of the profiling tool relative to a reference plane. Examples of suitable guidance devices include, but are not limited to, guidance devices produced by MicroTesIa of Houston, Tex. Each set of gamma ray measurements can be associated with such orientation so that a 2D profile map of the gravel filler can be generated precisely in terms of the actual azimuth location of the material in the gravel filler.

Figure 2 illustrates a perspective view of one embodiment of a gravel fill imaging tool. As shown, the wellbore imaging tool 200 includes a housing 230 carrying radiation source 220, source collimator 225, and a plurality of radiation detectors 240 in one arrangement. The detector array 240 may be positioned at a fixed distance from the radiation source 220. In certain embodiments, the detector arrangements may be positioned at different distances from the radiation source 220. Additionally, the detector arrangements on both The sides of radiation source 220 are also provided in certain embodiments. Electronics 260 may also be located in housing 230 or where convenient.

Radiation source 220 may be one or more radiation sources, which may include any suitable low energy gamma ray source capable of emitting gamma radiation from about 250 keV to about 700 keV. The gamma ray source suitable for use with the embodiments of the present invention may include any suitable radioactive isotope that includes, but is not limited to, barium, cesium, LINAC radioactive isotopes, high energy x-rays (e.g., about 200+ keV), or any combination thereof. Radiation from radiation source 220 may be continuous, intermittent, periodic, or in certain embodiments, amplitude, frequency, phase modulated, or any combination thereof.

In an exemplary embodiment, the radiation source 220 is centrally located in the housing 230. In the illustrated embodiment, the source 220 is positioned along the geometric axis of the housing 230.

The 225 gamma ray collimator, which is optional in certain

In these embodiments, it may be configured adjacent to source 220 for the purpose of directionally restricting radiation from radiation source 220 to a gravel fill azimuthal radiation segment. For example, collimator 225 may include fins or walls 226 adjacent source 220 to direct gamma ray propagation. By directing, focusing or otherwise directing radiation from radiation source 220, radiation can be guided to a more specific region of the gravel filler. It is appreciated that in certain embodiments, a heavy metal closure mechanism could additionally be employed to direct radiation from radiation source 220. In addition, radiation energy may be selected by choosing different isotopic sources so as to provide some discrimination of lithological or spatial depth.

In the illustrated embodiment collimator 225 restricts radiation from source 220. In that embodiment collimator 225 is also conically shaped as at 228 towards detectors 240 to collimate gamma rays from source 220. Obviously, those versed It will be appreciated in the art 10 that collimator 225 may be configured in any geometry suitable for directing, focusing, guiding or otherwise directing radiation from radiation source 220 to a more specific region of the gravel filler.

In a non-limiting example, radiation transmitted from source 220 into a gravel filler (such as gravel 150 of Figure 1) is dispersed by Compton back from the gravel filler to tool 200 wherein the scattered radiation back can be measured by radiation detectors 240. Radiation detectors 240 can be any plurality of sensors suitable for detecting radiation including gamma ray detectors. In the illustrated embodiment, four detectors are described, although several detectors may be used. In another exemplary embodiment, three detectors or six detectors are used; optionally each detector is arranged to "visualize" a different segment of the gravel filler. Using multiple detectors, the tool can imagine the entire circumference of the gravel fill in separately identifiable segments. The overall circumference image resolution may depend on multiple detectors, the gamma ray energy and the degrees of shielding provided around each detector. In certain embodiments, gamma ray detectors may include a scintillating crystal that emits light proportional to the energy deposited on the crystal by each gamma ray. A photomultiplier tube may be coupled to the crystal to convert the light from the scintillation crystal to the measurable 5-electron current or voltage pulse, which is then used to quantify the energy of each detected gamma ray. In other words, gamma rays are quantified, counted, and used to estimate the density of the gravel filler adjacent to the screen. Photomultiplier tubes can be replaced with a high temperature charge coupled device 10 (CCD) or microchannel photo amplifiers. Examples of suitable scintillating crystals that may be used include, but are not limited to, Nal, NaI (TI), BGO, and lanthanum-bromide crystals, or any combination thereof. Thus, counting rates can be measured from the returned radiation, in this case the returned gamma rays. The intensity of the 15 gamma rays scattered by Compton depends on, among other factors, the density of the gravel filler material. Thus, the lower density represents the gravel fill gaps and the lower counting rates represent the lower density as a result of fewer gamma rays being scattered back toward the detectors.

In an exemplary embodiment, detectors 240 are

mounted within a housing within a radius smaller than the housing radius 230 inserted from the housing surface 230. Similarly, although they need not be equally spaced, in the illustrated embodiment, detectors 240 are equally spaced in the housing. radius 25 selected. While the illustrated example shows four detectors 240 spaced 90 degrees apart, those skilled in the art will appreciate that multiple multiple detectors may be used in the invention. Moreover, while the embodiment illustrates all detectors 240 positioned at the same distance from source 220, they need not be spaced equally. Thus, for example, one detector (or multiple detector array) may be spaced 12 centimeters from the source, although another detector (or a detector array) is spaced 20 centimeters from the source or any other distance within the source. tool.

Similarly, in another embodiment, detectors 240 may be positioned both above and below source 220. In such a case, collimator 225 would be appropriately shaped to guide gamma rays in the direction of the desired detectors. In such embodiments with multiple detectors disposed on either side of the radiation source, additional shielding may be provided between the collimators to prevent radiation scattering (i.e. radiation cross contamination) of the different segment of the gravel filler.

Each detector 240 may be shielded from the other 15 detectors 240. Although any type of shielding configuration may be used for detectors 240, in the illustrated embodiment, collimator 248 is provided with a plurality of spaced openings or slots 245 each other around the perimeter of collimator 248. While openings 245 may be of any shape, such as round, oval, square or any other shape, in one exemplary embodiment, openings 245 are shaped as elongated slits and will be referred to as such. in this document.

A detector 240 is mounted on each slot 245 to enclose detector 240 in the shield. The width and depth of slot 245 25 may be adjusted as desired to achieve the desired azimuth range. In certain embodiments, the length of the slots 245 may be as long as the sensitive region of the gamma ray detector (e.g., the height of the crystal). It will be appreciated that since a detector is disposed within the slot, the detector is not on the surface of the collimator where it could otherwise detect gamma rays from a larger azimuthal band. In an exemplary embodiment, slot 245 is 360 ° (several detectors) degrees wide and the detector faces the inside diameter 5 of the pressure housing which is a few millimeters deep (for example, from about 2 to about 5 mm). However, closer collimation is possible. Optionally, the azimuth range of each slot is limited to 360 / (multiple detectors) degrees. In this way, the view of each radiation detector 240 may be more focused on a particular region of the gravel filler 10. Additionally, such shielding eliminates or at least softens scattered radiation from one detector to another detector. As can be seen, each detector is separated from each other by the radiation absorbing material. By eliminating more accurate azimuthal readings of detector-to-detector radiation dispersion are achieved.

Although the 225 source collimator is shown as a body

and integrally formed having fins 226, conical surface 228, it need not be and could be formed of separate structural components, such as a source collimator combined with a detector collimator 248, while the shield as described herein is achieved.

In the illustrated embodiment, the housing region 230 around the aperture in the source collimator and detectors 240 may be made of beryllium, aluminum, titanium, or other low atomic number metal or material, the purpose is to allow more gamma rays enter detectors 240. This design is especially important for lower energy gamma rays, which are preferably absorbed by any dense metal in the pressure housing.

Alternatively or in addition to detector shield or AO collimator 248, an anti-coincidence algorithm may be implanted in electronics 260 to compensate for detector-to-detector radiation scattering. In this way, a processor can alleviate the effects of multiple gamma rays detected by an anti-coincidence algorithm. In certain embodiments, electronics 260, 262, and 264 are located above detectors 240 or below source 220.

Electronics 260 may include processor 262, memory 263, and power supply 264 for powering the gravel filler imaging tool 200. Power supply 10 may be a battery or may be powered from from an external source such as a wiring (not shown). Processor 262 is adapted to receive measured data from radiation detectors 240. Measured data, which in certain embodiments include counting rates, may then be stored in memory 263 or further processed 15 before being stored in memory. memory 263. Processor 262 may also control the gain of the photomultiplier or other device for converting scintillations into electrical pulses. The electronics 260 may be located below or above the source 220 and above the detectors 240.

In one embodiment, the tool further includes a

accelerometer, a 3-axis inclinometer, or an attitude sensor to unambiguously determine the position of an azimuthal segment. In certain embodiments, a compass device may be incorporated to further determine the orientation of the tool.

The Gravel Filling Imaging Tool 200

It may be constructed from any material suitable for the downhole environment in which it is expected to be exposed, taking into account in particular the expected temperatures, pressures, forces, and chemicals to which the tool will be exposed. In certain embodiments, suitable building materials for source collimator 225 and detector collimator 248 include, but are not limited to, heavy metal, lead, very high dense atomic number (Z) materials, or any combination of the above. same.

In addition, although a 11/16 inch diameter configuration tool is illustrated, the tool 100 may be sized as desired for a particular application. Those skilled in the art will appreciate that the larger diameter tool would allow more detectors and shielding to provide additional segmentation of the gravel fill view.

This tool can be arranged to measure gravel fill integrity in new installations and to diagnose gravel fill damage from continuous production from the well. One person of ordinary skill in the art for the benefit of the present presentation will appreciate how to relate the results of the count rate and deduced density profile of the gravel filler to the filler structures and to consider from the results a condition of the gravel filler. filling.

As an additional illustration of an example geometry

From the embodiment illustrated in Figure 2, Figures 3A and 3B show cross-sectional views of another embodiment of the tool disposed in the base barrel or web 330, which is additionally disposed in the housing 310, which is additionally disposed in the gravel filler 350, wherein Figure 3A 25 shows a cross section taken from the XY plane and wherein Figure 3B shows a cross section taken from the XZ plane. As shown in the illustrated embodiment, the source collimator 328 is conically shaped in the X-Z plane or Y-Z plane. Detector 340 is shown in Figure 3A in openings or slots 345, wherein radiation source 320 is shown illustrated in Figure 3B. As shown in Figure 3A, detector collimators 348 are fan-shaped in the X-Y plane and rectangular in the X-Z or Y-Z planes. In certain embodiments, a source tapered collimator 328 is desirable as it reduces multiple scatter events in the gravel filler.

Methods for using the present invention may include the use of different energy windows to discriminate gravel filling in low to high density finishing fluids. In certain embodiments, at least three power windows are used wherein each window is dependent on the power source. For example, for a Cs (662 keV) source, the low energy (LE) window (typically from about 50 keV to about 200 keV) is sensitive to multi-dispersed source gamma rays, the window with high energy (HE) (typically from about 200 keV to about 350 keV) is sensitive to uniquely dispersed source gamma rays. A wide window (BW) can typically include gamma rays in the range of about 50 keV to about 350 keV. The BW count rate has the highest statistical accuracy and is used for gravel fill base imaging. LE and HE windows can be used for specific applications such as depth reading and maximum dynamic range imaging capabilities. Combinations of these different power window profiles can be combined using special methods (eg, adaptive ad-hoc or Kalman-type processing algorithms) for improved accuracy and resolution. It is recognized that multiple intensity power sources may be used in the same tool, either simultaneously or sequentially.

In addition to the radiation source energy levels, other factors that can be adjusted to discriminate segmented views of the gravel fill include, but are not limited to the angle of the collimators and the detector source for spacing. Examples of suitable source collimator angles include, but are not limited to, angles of about 15 degrees to about 85 degrees and from about 65 degrees to about 85 degrees in other embodiments. Examples of suitable source spacing for the detector include, but are not limited to, from about 2.54 cm (1 inch) to about 8.89 cm (3.5 inch) to about 20.32 cm (8 inches). inches), and in other embodiments, from about 15.24 cm (6 inches) to about 25.4 cm (10 inches), and in still other embodiments about 10 30.48 cm (12 inches).

Radioactive trackers can be used in conjunction with certain embodiments to produce enhanced gravel filler images. The introduction of radioactive trackers allows the production of an azimuthally distributed image of radioactive tracker 15. Radioactive trackers can be attached to the gravel filler before constructing the gravel filler or as the gravel filler is arranged. Alternatively, radioactive trackers may be injected or otherwise introduced into the gravel filler after installation of the gravel filler 20 (e.g. as a fluid or as a paste). More generally, radioactive trackers may be introduced into any portion of the formation, such as the well.

When radioactive tracker material is attached to the gravel itself prior to disposal, vacuum areas appear in the images as 25 regions with low (or “dark”) counts, where radioactive tracker material is injected as fluid or as a paste. , vacuum areas of vacuum areas appear in the images as high-count (or “light”) regions within the gravel filler. Additional image enhancement can be achieved by using a variety of trackers to create a multiple isotope profile. When used for this purpose, font 320 in Figure 3, 220 in Figure 2, or 120 in Figure 1 may be omitted from the tool. Alternatively, the tracker radioactivity may be determined in the presence of the radiation source or multiple trackers may be identified using the energy discriminating capability of the electronics 260.

In addition, it is recognized that the downhole tool is capable of measuring counting rates even though it is lowered or raised in the 10 hole. In certain embodiments, the downhole tool can perform measurements even though the tool is motionless in the hole. Exemplary lowering elevation rates include travel rates of up to about 54,864.000000001 centimeters / hour (1800 feet / hour).

To facilitate a better understanding of the present invention, the following examples of certain aspects of some embodiments are provided. In no way should the following examples be read to limit or define the scope of the invention.

Examples

In a nonlimiting example of use, Figure 4 illustrates a graph 20 of a gamma ray spectrum incident on one of the detectors as a response to being dispersed in a gravel filler. In this the typical gamma ray intensity is shown plotted versus the gamma energy (MeV). This graph shows an MCNP modeled detector energy spectrum simulation of a real tool that results from the 356 keV 133Ba Compton gamma ray 25 scattered back in various gravel fill scenarios. This chart is an advantage for choosing a low power range source. By using a power source that is low enough, it can be ensured that the gravel filler tool is sensitive mainly to variations in regions close to gravel filler and is not significantly affected by dispersion in deeper cement regions. around the compartment or formation and the subsequent formation density variations. However, in the case of thick base pipes and wire mesh between the gravel filler and gravel filler tool detectors, the source energy needs to be high enough to penetrate into the gravel filler screen. In this way, gravel filler imaging tools can be designed to "focus" 10 on depths or portions of a particular gravel filler.

In a non-limiting example of use, Figure 5 shows a graph of a counting rate versus depth in centimeters as measured by an 8.89 cm (3.5 inch) gravel filler in a filler. 7 inches (17,78 cm) gravel. These profiles were produced by processing individual detector gamma ray count rates. The plot in Figure 5 is an MCNP-modeled example of the counting rate sensitivity for a 2.54 cm (1 inch) annular space undermining in a centered gravel filler at a depth of 4 centimeters. It shows significant sensitivity to changes in gravel fill density. Qualitative image profiles will be produced by displaying the count rates of each detector sector at each depth. Another means of analyzing the count can be used to compute a more quantitative multiple sector density profile (ie, in grams / cc). Such a density profile can be derived from counting rates by using a counting rate algorithm for calibrated profiling density.

Notably, the traditional prior art density tool used to measure gravel fill generally has a relatively large spacing between the source and the detector. The reason for this is that the tool is provided to evaluate all gravel filler. The source and detector are both typically centrally located in the tool along the tool axis. The shield may be provided along the geometry axis between the source and the detector to prevent energy coupling between the two, i.e. energy passing directly from the source to the detector without dispersion within the gravel filler. In the prior art, because of the relatively large spacing between source and detector, gamma ray radiation undergoes significant multiple scattering and absorption before it is detected and counted. The denser the gravel filling, the lower the recorded count. In other words, in the prior art tools, the counting rate decreases with the gravel fill density because multiple dispersion and absorption attenuates the total amount of radiation measured by the detectors.

In an exemplary embodiment of the device and method of the present disclosure, the source and detectors are positioned in close proximity to each other, such as about 8.89 cm (3.5 inches) apart. Because of this close physical relationship, the energy propagated into the gravel fill and dispersed back to the detector goes through much less diffusion, that is, typically just a single diffusion (back to the detector) as opposed to multiple dispersion. In fact, the counting rates increase with the density of the gravel filler by using the tool of the invention. This is significant because it means that radiation does not go through the attenuation associated with prior art tools.

Furthermore, the prior art does not use a conically shaped collimator to direct the propagated energy into the gravel filler. Again, by using such a collimator in the prior art tool, multiple dispersion can be minimized and improved by imaging the prior art tools.

Referring now to Figure 6, a partial side sectional view

is provided to illustrate an exemplary embodiment of tool 400 disposed in a hole 402 that crosses a formation 404. Tool 400 is suspended in a wiring 406, which may be threaded through a wellhead assembly 408 shown surface and bore 402. Optionally, the tool 400 could be disposed in the piping, piano string, cable, or any known or further developed arrangement. An outer housing 410 that can be cemented in the formation 404 delineates the hole 402 and an inner housing 412 is shown coaxially inserted into the outer housing 15 410. Tool 400 is suspended within the production pipe 414 that inserts into the housing. inner compartment 412; a decentralizer 416 shown mounted on a side side of tool 400 to propel tool 400 upwardly against the inner surface of production line 414. In one example, and as described in more detail below, decentralizing tool 400 enhances the imaging of annular spaces between the concentric tubes.

Referring now to Figure 7, shown in more detail is a side sectional view of a portion of the embodiment of Figure 6. Fluid 418 is shown in the example of Figure 7 in production line 414. Fluid 418 also occupies the length. of an annular space 420 between the inner and outer columns of compartment 410, 412 and a portion of an annular space 422 between internal compartment 412 and production pipe 414. Below the fluid 418 and annular space 422 there is a precipitate substantially solid 424 extending between line 414 and inner compartment 412. In the example of Figure 7, precipitate 424 adheres to line 414 to internal compartment 412. In one example, precipitate 424, which may fall or precipitate from of fluid 418, may be substantially made of baritine.

Figure 8A is a sectional view of tool 400 in hole 402 taken along lines 8A-8A of Figure 7. In the example of Figure 8A, production line 414 is substantially concentric within inner housing 412. Thus, in example Figure 8A the thickness Ar is substantially the same around the entire circumference of annular space 422. Also shown in Figure 8A are detectors 4261-6 which are provided within the tool body 400. In the example of Figure 8A, tool 400 is positioned against the inner surface of tubing 414 so that detector 4261 is the detector closest to the sidewall of tubing 414. In contrast, detector 4264, which is illustrated to be about 180 ° from of detector 4261, is the farthest detector from the side wall of pipe 414 against which tool 400 is thrust against.

Referring now to Figure 8B, the partial side sectional view of the embodiment of Figure 8A is shown taken along lines 8B-8B and illustrates a spatial relationship of detectors 4261, 4264 and a radiation source 428. In the example of Figure 8B and as described above, radiation source 428 emits radiation that is directed along dedicated paths to improve detection of scattered gamma rays. Still referring to Figure 8B, the paths P1, P4 are shown and illustrate an exemplary radiation direction 25 directed to the detection by detectors 4261, 4264 respectively. By the asymmetric arrangement of the tool 400 within the pipe 414, the radiation directed along path P1 exits tool 400 and passes through tubing 414 and into annular space 422. At least a portion of the radiation along P1 that travels into annular space 422 disperses back and is detected by detector 4261. As will be described in more detail below, analyzing the radiation detected from detector 4261 can provide 5 information about the material disposed within annular space 422. In contrast, radiation directed along path P4 travels its path. from tool 400 and is directed into fluid 418 within tubing 414. The strategic location of source 428 and detector 4264 provides detection of radiation that mainly disperses from fluid 418. Thus, in an exemplary embodiment, a study of scattered radiation monitored by detector 4264 may provide a reference or basis for analysis. of the scattered gamma rays detected by detector 4261.

Figure 9A, like Figure 8A, is a sectional view of an example of tool 400 disposed in hole 402 taken sideways to the axis 15 AX of hole 402 (Figure 8B). In the example of Figure 9A, the tubing 414 is arranged asymmetrically within the inner housing 412 so that the thickness Ar1 of the adjacent annular space 422 where the tool 400 is located is smaller than other azimuthal portions of the annular space 422. The asymmetric positioning of the pipe 414 is shown in a longitudinal sectional view in Figure 9B along its representative directional paths P1, P4 illustrating exemplary directions of radiation emitted from source 428.

Referring now to Figure 10, a simulated counting rate as recorded by detectors 4261, 4264 is graphically provided. More specifically, curves C1, C2 respectively illustrate situations in which the counting rates obtained by detectors 4261, 4264 may vary with changes in annular space thickness 418. Curve C1 illustrates a simulated response in which a liquid is present in the annular space 422. The abscissa of Figure 10 represents a change in annular space thickness, where the ordinate represents a ratio of detector count rate 4261 to detector count rate 4264. As shown, the ratio of count rates of detectors 4261, 4264 decreases with 5 decrease in annular space thickness 422. The decrease in counting rates can be attributed to more radiation passing entirely through the smaller annular space 422 and in contact with the inner surface of the inner compartment 412. The highest density of the material in compartment 412 over the density of the liquid which can attenuate 10 radiation. o so that dispersion cannot be observed at the energy level that is detected by detector 4261.

Curve C2 of Figure 10 represents a simulated example where annular space 422 is substantially filled with a particulate matter such as baritin. In this example, the response ratio 15 remains consistent enough despite changes in annular space thickness 422. One plausible conclusion is that the baritin radiation scatter rate is substantially the same as that of another material that makes up the inner compartment 412. Equipped with this knowledge, tool 400 can be successfully disposed within the concentric tubes 20 and used to determine material within the annular spacing space of the tubes. In addition, changes in tube coaxial orientation should not affect the tool's ability to identify material within the annular space.

Figure 11 illustrates a series of C3-C15 plots representing a counting response detected by a scattered radiation detector within various materials having different densities. More specifically, the material density represented by the C3 plot is about 1.1982642681 grams per ml (10 pounds per gallon), the material density represented by each successive line increases by about

0.23965285362 grams per ml (two pounds per gallon). Thus, the material density represented by the C4 plot is about 1.43791712172 grams per ml (12 pounds per gallon) and so on with the material density represented by the C4 plot to be about 3.83444565792 grams per ml (32 pounds per gallon). Line C15 represents baritin. In this example, the abscissa represents the thickness of the annular space and the ordinate represents the detected response. As can be seen from Figure 11, the response remains more consistent with changes in annular space thickness for higher density substances as opposed to those with lower density. As with the response of Figure 10, the reduced thickness of the annular space allows radiation to contact the inner surface of the housing, thereby attenuating the radiation. A Monte Carlo modeling code MCMP was used as the modeling software that produced the data from which Figure 11 was generated.

Referring now to Figure 12A, an example of a tool 400A illustrating a hole 402A is shown in a partial side sectional view. In this example a centralizer 430 is provided on a body 431 of tool 400A and holds tool 400A near the median portion of hole 402A. A portion of hole 402A adjacent tool 400A is shown and has a gravel filler 432 that is comprised of several pellets 434, such as a holding material. Part of the gravel filler 432 is disposed in annular space 420 and another part extends radially outwardly into the surrounding formation 404A through perforations 436 in the housing 437 shown as delineating hole 402A. In the example of Figures 12A and 12B a single housing column is in hole 402A. In an alternate embodiment, the portion of housing 437 having perforations 436 may be a glove coupled to the remaining column of housing 437. In addition, a screen (not shown) may be incorporated within the production pipe 414 to filter sand and other materials. particles that may enter production piping 414. As described in 5 more details above, gravel filler 432 can be imaged by directional radiation from source 428 along Pi-Pn1 paths where radiation dispersion is detected. with detector 426. Although a single detector 426 is illustrated in the embodiment of Figure 12A, multiple detectors 426 may be included. In one use example, the gravel filler 432 imaging obtained by tool 400A, including other portions of hole 402A or 404A, may provide an image of the "baseline" gravel filler 432.

In one example, the baseline image may be obtained before any fluid production through the gravel filler 15 432 has occurred. Referring now to Figure 12B, the partial partial sectional view of an example of how fluid flows over a period of time through the gravel filler 432B from formation 404B may introduce a quantity of debris 438 into the filler with gravel. gravel 432B. In one example, the debris 438 includes fine or other solid particles that occupy the interstices between the pellets 434B that make up the gravel filler 432B, thereby restricting the flow of fluid from the 404B formation through the gravel filler 432B and into hole 402B. By arranging tool 400A within hole 402B and directing radiation from source 428 along 25 Pi-Pn paths and to detector 426, as shown in Figure 12B, an image of debris 438 in the gravel filler 432B can be obtained. Thus, the presence of debris 438 can be identified or confirmed by comparing a baseline image of the gravel filler 432 with the image obtained later.

In one example, the baseline image may be obtained prior to repairing or repairing the gravel filler 432, where an example repair / repair is an acidification procedure. Referring now to Figure 12C, hole 402C is imaged with tool 400A after operations to repair or repair gravel filler 432C have taken place. In the example of Figure 12C, the 432C gravel filler still contains 438C debris that was not removed during the repair attempt. Then, by imaging the gravel filler 432C 10 with tool 400A as shown, radiation from source 428 disperses within the gravel filler 438C and detected by detector 426. Thus, the diffusion analysis detected can reveal the presence of and a location of the remaining debris 438C. Imaging hole 402C with tool 400A after a repair or repair of the 432C gravel filler can verify the successful repair procedure, and if not, can reveal how deep and azimuthal debris 438C remains in the 432C gravel filler . Based on this information, decisions for future or additional repairs / repairs can be made.

In Figure 13, the side sectional view of an exemplary embodiment 400A is shown disposed in a bore 402 wherein different types of and / or cement weight densities are disposed between the housing 437 and the surrounding formation 404. More specifically, a portion of the cement bond is composed of a lightweight cement 440 shown disposed in annular space 420. In one example, lightweight cement 25 describes the cement between a housing and a formation having a density of up to about 1 , 43791712172 grams / ml (12 pounds / gallon). Also illustrated in the example of Figure 13 is a normal weight cement 442 disposed in annular space 420 above light weight cement 440. For purposes of discussion herein, normal weight cement may include cements between a housing and a formation which has a density greater than about 1.43791712172 grams / ml (12 pounds / gallon). The tool 400A of Figure 13 is configured so that radiation from its source 428 is directed along the paths Pi-Pn and that radiation dispersion occurring within annular space 420 having cement 440, 442 is detected. detector 426. Because of the sensitivity and resolution of tool 400A, radiation will disperse from light weight cement 440 unlike how it will disperse from 10 light weight cement 442. In addition, an analysis From differences in detection of detector 426 when tool 400A is disposed adjacent to different cements 440, 442, it can identify the specific locations of these different cements 440, 442.

Referring now to Figure 14, an example of tool 400A is illustrated in a partial side sectional view disposed in a bore 402 where asphaltenes 444 are produced from formation 404. In that example, asphaltenes 444 may become housed in the gravel filling 432 in the well as drilling 436 occurs in housing 437. Similar to the example of the operation of Figure 13, radiation from source 428 in tool 400A is directed radially outwardly from tool 400A so that a part of the radiation disperses from asphaltenes 444 in gravel filler 432 or screen 436. Detecting radiation diffusion with detector 426 and analysis of detection results may indicate the presence and / or location of asphaltenes 444 in filler gravel 432 or screen 436. In one example, the presence of asphaltenes is detected by detecting the radiation energy level (s) detected with detector 426 to be consistent with the radiation energy level (s) known to diffuse from asphaltenes 444. In Figure 15, an exemplary embodiment of tool 400A is shown in a side partial sectional view. In this example the tool 400A is equipped with a centralizer 430 which positions the tool 400A toward the median portion of hole 402. Radiation is directed from source 428 along the paths P, -Pn so that the radiation that is dispersed from annular space 420 can be detected by receiver (s) 426. In one example, strategically forming collimator 328 (Figure 3B) and spatially locating source 428 and detector (s) 426 allows detection of the desired radiation diffusion by detector (s) 426. Also optionally, monitoring dispersion in a selective energy range may indicate material disposed in annular space 420. In the example of Figure 15, the precipitate 424 is detected in annular space 420 by analyzing the scattered radiation count detected by sensor (s) 426, wherein the precipitate 424 may include baritin.

The present invention described herein is therefore

It is well adapted to achieve the objectives and achieves the purposes and advantages mentioned, as well as others inherent to it. While a presently preferred embodiment of the invention has been provided for presentation purposes, numerous changes exist in the details of the procedures for achieving the desired results. These and other similar modifications will readily appear by themselves to those skilled in the art and are intended to be encompassed within the spirit of the present invention set forth herein and within the scope of the appended claims.

Claims (21)

A method of conducting an underground bore 402, comprising: directing radiation from within a tube 412 disposed in the underground bore 402 and along an oblique path to a geometrical axis of the tube 412 such that at least a portion of the radiation passes through tube 412 into an annular space 422 that circumscribes tube 412 and disperses back into tube 412; detecting radiation scattering back into the tube 412; and characterized by identifying a material in annular space 422 based on a radiation detection rate. Method according to claim 1, characterized in that the radiation comprises a first set of radiation and the path comprises a first trajectory, the method being further characterized by the fact that: directs a second set of radiation along a second path having an azimuthal component that is substantially 180 ° from an azimuthal component of the first path such that at least a portion of the second radiation array is dispersed from the fluid disposed in tube 412 and detects the second a scattered radiation array, wherein the step of identifying a material in annular space 422 is further based on a detection rate of the second radiation array. Method according to claim 1 or 2, characterized in that the radiation comprises a gamma ray from a gamma ray source 428 having an energy of about 250 keV to about 700 keV and wherein the scattered radiation, when detected, has an energy of about 50 keV to about 350 keV. Method according to any one of claims 1 to 3, characterized in that by repeating steps (a) to (c) at a different depth in hole 402 and wherein a thickness of the annular space 422 varies around a circumference of annular space 422 such that a detectable amount of energy of at least a portion of the radiation is attenuated within an outer tube 437 that surrounds annular space 422. A method according to claim 2, further characterized in that: repeating steps (a) to (c) at a different depth in the hole in which annular space 422 has a thickness that varies over a circumference of annular space 422 so that a detectable amount of energy from at least a portion of the radiation is attenuated within an outer tube 437 circumscribing annular space 422, and detecting a fluid in annular space 422 when a ratio of the rate of Detection of the first set of radiation above the detection rate of the second set of radiation decreases when the thickness decreases. Method according to claim 5, further characterized by the fact that upon detection of a substantially solid material in annular space 422 when a ratio of the detection rate of the first set of radiation above the detection rate of the second set of The radiation remains substantially the same with changes in thickness. Method according to any one of claims 1 to 6, characterized in that the material in the annular space 422 comprises a light weight cement. A method according to any one of claims 1 to 7, characterized in that the radiation is from a source 428 disposed in a downhole tool 200 disposed in tube 412 and at a location selected from of a group consisting of asymmetrically against an inner surface of tube 412 and a median portion of tube 412. 9. A method for checking annular space 422 between an inner tube 412 and an outer tube 437 which are arranged coaxially in an underground bore 402, the method comprising: a. providing a gamma ray source 428 disposed in a profiling instrument against an azimuth section of inner tube 412; B. directing the gamma rays from source 428 so that some of the gamma rays move through the sidewall of the profiling instrument into annular space 422 and diffuse from material in annular space 422 back inwardly inner tube 412 and so that some of the gamma rays move away from the azimuthal section of the profiling instrument and diffuse from a fluid in inner tube 412; ç. detecting the scattered gamma rays and classifying the gamma rays that disperse from the fluid in the inner tube 412 and those that scattered from the material in annular space 422; and characterized by d. identify material in annular space 422 based on a scattered gamma ray detection rate. Method according to claim 9, characterized in that a conically shaped guide is provided near the gamma ray source 428 and positioned on the profiling instrument such that a guide apex is directed towards the source 428 and the guide has a geometry axis that is substantially parallel to a geometry axis of the inner tube 412. Method according to claim 9 or 10, characterized in that a detector is arranged from about 5.08 cm (2 inches) to about 10.16 cm (4 inches) from the lightning source. gamma428 and where the detector is used to detect scattered gamma rays. Method according to any one of claims 9 to 11, characterized in that a collimator 225 is used to strategically direct gamma rays away from source 428 at an oblique angle to a geometry axis of inner tube 412 and along discrete paths arranged azimutally around the gamma ray source 428, so that strategically located detectors detect, respectively, dispersion from radially outwardly distinct azimuthal areas from gamma ray source 428. A method according to any one of claims 9 to 12, characterized in that a rate of detection of gamma rays deviating from the fluid in the bore is used as a reference for determining material in annular space. . A method according to any one of claims 9 to 13, further characterized in that by repeating steps (a) to (d) at different depths in a hole section and identifying a substantially solid material in the annular space 422 when a ratio of a detected gamma ray rate that is dispersed from the annular space 422 above a detected gamma ray rate that is dispersed from the fluid in the inner tube 412 remains substantially the same with changes in the thickness of the annular space 422. A method according to any one of claims 9 to 14, further characterized by the fact that by repeating steps (a) to (d) at different depths in a hole section and identifying a material substantially annular space 422 when a ratio of a detected gamma ray rate that is dispersed from annular space 422 above a detected gamma ray rate that is dispersed from fluid in the inner tube 412 is reduced with a reduction in thickness of annular space 422. Method for analyzing an annular space 422 between an inner tube 412 and an outer tube 437 which are arranged coaxially in an underground bore 402, the method comprising: a. providing a gamma ray source 428 disposed in a profiling instrument against an azimuth section of inner tube 412; B. direct gamma rays from source 428 so that some of the gamma rays move into annular space 422 and diffuse from material in annular space 422 back into inner tube 412 and so that some of the gamma rays move away from the azimuthal section and disperse from a fluid in the inner tube 412; ç. detecting the scattered gamma rays and classifying the gamma rays that disperse from the fluid in the inner tube 412 and those that disperse from the material in annular space 422; characterized by d. identify material in annular space 422 based on a scattered gamma ray detection rate; and is. repeat steps (a) to (d) at different depths in a section of the hole, identify a substantially solid material in annular space422 when a ratio of a detected gamma ray rate is scattered from annular space 422 above a The detected gamma ray rate that is dispersed from the fluid in the inner tube 412 remains substantially the same with changes in annular space thickness 422, and identifies a substantially liquid material in the annular space 422 when a ratio of a detected gamma ray rate that are dispersed from annular space 422 above a rate of detected gamma rays that are dispersed from fluid in inner tube 412 is reduced with a reduction in annular space thickness 422. A method according to claim 16, further characterized by the fact that by repeating step (e) along the sections of hole 402 which are at different depths. Method according to claim 16 or 17, characterized in that the rate of gamma rays that are dispersed from the fluid in the tube 412 comprises a reference value for use in identifying a liquid in the annular space 422. . A method for monitoring an underground gravel filler 432 which comprises: forming a baseline image of the gravel filler 432 by directing radiation into the gravel filler 432 and detecting radiation scatter from the filler with gravel 432; at a point in time after forming the baseline image, forming an updated image of gravel filler 432 by directing radiation into gravel filler 432 and detecting radiation scatter from gravel filler 432; compare the baseline image and the updated image; and characterized by identifying a material that has migrated into the gravel filler 432 within a period of time between when the baseline and the updated images are formed. Method according to claim 19, characterized in that the material is selected from a group consisting of debris 438 of a formation adjacent to the gravel filler 432 and asphaltenes 444. The method of claim 19 further characterized by the fact that by forming an image of the gravel filler after repair 432 by directing radiation into the gravel filler 432 and detecting radiation scatter at starting from gravel filler 432 at a point in time after forming the baseline image and after gravel filler 432 has been repaired.