Patent ID: 12247480

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

Certain examples commensurate in scope with the originally claimed subject matter are discussed below. These examples are not intended to limit the scope of the disclosure. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the examples set forth below.

When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, unless expressly stated otherwise, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B.

As mentioned above, a radiation-based downhole tool may emit radiation into a geological formation and detect the radiation after it has interacted with the geological formation. Such a radiation-based downhole tool may include a photonic radiation source (e.g., a radioisotopic source such as cesium (e.g.,137Cs), an x-ray generator) or a neutron source (e.g., an electronic neutron generator). In one example, a formation density tool may include a source to emit high-energy photons into the geological formation. While this disclosure generally refers to a formation density tool by way of example, it should be understood that the systems and methods of this disclosure may be used with any suitable radiation-based downhole tool that uses radiation detector windows. Continuing with the example of a formation density tool, some of the high-energy photons may be scattered by the geological formation and then detected by one or more detectors on the formation density tool. The physical properties of the geological formation may be determined from the characteristics of the detected high-energy photons. The accuracy of the determined physical properties depends on the ability of the downhole tool to capture photons travelling through the formation at the one or more detectors. Restricting the direct passage of photons from the source to the one or more detectors inside the formation density tool without travelling through the formation increases the accuracy of the determined physical properties. Accordingly, as will be described in more detail below, the present disclosure provides techniques to ensure that more accurate physical properties of a geological formation are determined by providing shielding and/or collimation for detectors in a formation density logging tool.

Turning now to the figures,FIG.1depicts a schematic diagram of a formation density logging tool100that may obtain physical properties of a geological formation, in accordance with an embodiment. The formation density logging tool100may be a component of a wireline or slickline tool or bottom-hole assembly (BHA) as a logging-while-drilling (LWD) or measurement-while-drilling (MWD) tool. The formation density logging tool100may transmit measurements that may be stored and processed downhole or may be sent to the surface for processing.

The formation density logging tool100may include a first housing102, an external shield104, one or more detector windows106, one or more detector window covers108, a source110, a source aperture112, one or more shielding inserts114, and one or more detectors116. The source110may be any suitable radiation source (e.g., a nuclear or photonic radiation source). For instance, the source110may be photon source, such as an x-ray generator, a gamma ray generator, a cesium source, or any other suitable source that emits photons, such as x-rays, gamma rays, or other high-energy photons. High-energy photons may include photons at an energy sufficient to cause at least a portion of the photons to inelastically scatter off elements of the geological formation and to be absorbed by the one or more detectors116(e.g., Compton scattering). The source110emits the photons such that at least some of the photons enter the geological formation. At least some of the photons may interact with the geological formation (e.g., scatter) and may be redirected towards the one or more detectors116. In certain embodiments, at least one of the one or more detectors116may be a short-spaced detector and at least one of the one or more detectors116may be a long-spaced detector located farther from the source110than the short-spaced detector.

Each of the one or more detectors116may include a scintillator120that absorbs the photons and emits light based on the energy of the absorbed photons. For example, each emission of light may count as a detected photon (e.g., thereby adding one to a count rate of the detector). Each of the one or more detectors116may also include a photomultiplier118operatively coupled to the scintillator120to detect the light emitted by the scintillator120. The photomultiplier118may output an electrical signal from the detected light of the scintillator. Processing of the electrical signals from the photomultiplier118may be performed at a data processing system at the surface and/or at a data processing system within the BHA.

The one or more detector windows106may be at least partially disposed in one or more recesses of the first housing102. Further, the one or more detector windows106may be at least partially disposed in one or more recesses of the external shield104. The one or more detector windows106may be capable of withstanding high wellbore pressures. For example, the one or more detector windows106may be capable of withstanding at least seventy megapascals (MPa). The one or more detector windows106may have a small photoelectric cross section. For example, the one or more detector windows106may be formed of a material having a low atomic number. In one example, the one or more detector windows106may be formed of a material having an atomic number less than twenty-three. Additionally or alternatively, the one or more detector windows106may have a small Compton cross section. For example, the one or more detector windows106may be formed of a material having a low density. For example, the one or more detector windows106may be formed of a material having a density less than five grams per cubic centimeter. In certain embodiments, the one or more detector windows106may be formed of at least one of beryllium, titanium, an alloy of beryllium, an alloy of titanium, a carbon composite, a layered aluminum, or any combination thereof. The one or more detector windows106may be coupled to the first housing102. For example, the one or more detector windows106may be welded, brazed, sealed with elastomeric materials, or any other suitable form of sealing. The one or more detector window covers108may surround an outer surface of the one or more detector windows106.

Shielding inserts114may prevent leakage of high-energy photons from the source110through an interior of the formation density logging tool100to the one or more detectors116. At least one of the shielding inserts114may be disposed about the source110. The at least one of shielding inserts114disposed about the source110may include an aperture. The aperture may allow passage of high-energy photons from the source110. The aperture may be substantially aligned with the source aperture112. The source aperture112may be formed within a portion of the external shield104. The source aperture112may allow passage of high-energy photons from the source110to an exterior of the formation density logging tool100. The source aperture112may allow passage of high-energy photons from the source110to a geological formation.

With the preceding in mind,FIGS.2A and2Bdepict a schematic diagram and a schematic cross section diagram of a detector window200for a formation density logging tool having a dome202and an interval cavity204, in accordance with an embodiment. The detector window200may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window200may include the dome202, the internal cavity204, a set of flanges206, a wall208, and an aperture210. The detector window200may be generally circular or take any other suitable shape along an outer surface of the downhole tool (e.g., rectangular, square). Each flange of the set of flanges206may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges206and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window200may be welded and/or brazed in the recess of the housing of the formation density logging tool (e.g., in which case the elastomeric O-ring may be present or ab sent).

The dome202may be an exterior dome. For example, the dome202may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The dome202may be a solid dome. The dome202may have an arcuate shape at a first surface202A and/or a second surface202B. The first surface202A may be an inner surface. For example, the first surface202A may face the interior cavity204. The second surface202B may be an outer surface. For example, the second surface202B may face away from the interior cavity204. In some embodiments, the interior cavity204may be filled with a material. For example, the interior cavity204may be filled by inserting a material through the aperture210. The aperture210may be formed through the wall208. The wall208may be an interior wall. For example, the wall208may face towards an interior of the formation density logging tool.

With the preceding in mind,FIGS.3A and3Bdepict a schematic diagram and a schematic cross section diagram of a detector window300for a formation density logging tool having a shell dome302, in accordance with an embodiment. The detector window300may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window300may include the dome302, an internal cavity304, a set of flanges306, a support structure308, and one or more apertures310. The detector window300may be circular. Each flange of the set of flanges306may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges306and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window300may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The shell dome302may be an exterior dome. For example, the shell dome302may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The shell dome302may have an arcuate shape at a first surface302A and/or a second surface302B. The shell dome302may be a hollow dome. For example, the shell dome302may include an interior cavity disposed between the first surface302A and the second surface302B. The support structure308may be disposed between the first surface302A and the second surface302B. For example, the support structure308may be disposed in an interior cavity of the shell dome302between the first surface302A and the second surface302B. The support structure308may support the dome302from wellbore pressure exterior to the formation density logging tool. The support structure308may have a corrugated shape. The support structure308may be coupled to the first surface302A and/or the second surface302B. In certain embodiments, the interior cavity of the shell dome302may be filled with a first material. For example, the interior cavity of the shell dome302may be filled by inserting the first material through at least one of the one or more apertures310. The first surface302A may be an inner surface. For example, the first surface302A may face the interior cavity304. The second surface302B may be an outer surface. For example, the second surface302B may face away from the interior cavity304. The one or more apertures310may be formed through the first surface302A. For example, the one or more apertures310may be disposed in the first surface302A.

With the preceding in mind,FIGS.4A and4Bdepict a schematic diagram and a schematic cross section diagram of a detector window400for a formation density logging tool having a dome402and a column structure408, in accordance with an embodiment. The detector window400may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window400may include the dome402, an internal cavity404, a set of flanges406, and a column structure408. The detector window400may be circular. Each flange of the set of flanges406may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges406and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window400may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The dome402may be an exterior dome. For example, the dome402may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The dome402may be a solid dome. The dome402may have an arcuate shape at a first surface402A and/or a second surface402B. The first surface402A may be an inner surface. For example, the first surface402A may face the interior cavity404. The second surface402B may be an outer surface. For example, the second surface402B may face away from the interior cavity404. In some embodiments, the interior cavity404may be filled with a material. The column structure408may be coupled to the dome402at the first surface402A. The column structure408may be a support structure. The column structure408may support the dome402from wellbore pressure exterior to the formation density logging tool. The column structure408may include a plurality of columns. In certain embodiments, each of the plurality of columns may be hollow. In certain embodiments, each of the plurality of columns may have a hexagonal shape. The interior cavity404may be a plurality of hollow portions of the plurality of columns. In certain embodiments, each of the plurality of columns includes a hollow portion.

With the preceding in mind,FIGS.4C and4Ddepict a schematic diagram and a schematic cross section diagram of a detector window420for a formation density logging tool having a column structure428, in accordance with an embodiment. The detector window420may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window420may include a cap422, an internal cavity424, a set of flanges426, and the column structure428. The detector window420may be circular. Each flange of the set of flanges426may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges426and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window420may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The cap422may be an exterior cap. For example, the cap422may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The cap422may be a solid cap. The cap422may have a flat shape at a first surface422A and/or a second surface422B. The first surface422A may be an inner surface. For example, the first surface422A may face the interior cavity424. The second surface422B may be an outer surface. For example, the second surface422B may face away from the interior cavity424. In some embodiments, the interior cavity424may be filled with a material. The column structure428may be coupled to the dome422at the first surface422A. The column structure428may support the cap422from wellbore pressure exterior to the formation density logging tool. The column structure428may include a plurality of columns. In certain embodiments, each of the plurality of columns may be hollow. In certain embodiments, each of the plurality of columns may have a hexagonal shape. The interior cavity424may be a plurality of hollow portions of the plurality of columns. In certain embodiments, each of the plurality of columns includes a hollow portion.

With the preceding in mind,FIGS.5A and5Bdepict a schematic diagram and a schematic cross section diagram of a detector window500for a formation density logging tool having a dome502and a truss structure508, in accordance with an embodiment. The detector window500may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window500may include the dome502, an internal cavity504, a set of flanges506, the truss structure508, and one or more apertures510. The detector window500may be circular. Each flange of the set of flanges506may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges506and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window500may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The dome502may be an exterior dome. For example, the dome502may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The dome502may have an arcuate shape at a first surface502A and/or a second surface502B. The dome502may be a hollow dome. For example, the dome502may include an interior cavity between the first surface502A and the second surface502B. The truss structure508may be disposed between the first surface502A and the second surface502B. For example, the truss structure508may be disposed in an interior cavity of the dome502between the first surface502A and the second surface502B. The truss structure508may support the dome502from wellbore pressure exterior to the formation density logging tool. The truss structure508may include a plurality of columns. In certain embodiments, the truss structure508may include a plurality of spokes, ribs, or concentric rings. The truss structure508may be coupled to the first surface502A and/or the second surface502B. In certain embodiments, the interior cavity of the dome502may be filled with a first material. For example, the interior cavity of the dome502may be filled by inserting the first material through at least one of the one or more apertures510. The first surface502A may be an inner surface. For example, the first surface502A may face the interior cavity504. The second surface502B may be an outer surface. For example, the second surface502B may face away from the interior cavity504. In certain embodiments, the first surface502A may have a greater curvature than the second surface502B. In some embodiments, the interior cavity504may be filled with a material. The one or more apertures510may be formed through the first surface502A. For example, the one or more apertures510may be disposed in the first surface502A.

With the preceding in mind,FIGS.6A and6Bdepict a schematic diagram and a schematic cross section diagram of a detector window600for a formation density logging tool having a hub610and spoke608structure, in accordance with an embodiment. The detector window600may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window600may include a dome602, an internal cavity604, a set of flanges606, one or more spokes608, the hub610, and an aperture612. The detector window600may be circular. Each flange of the set of flanges606may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges606and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window600may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The dome602may be an exterior dome. For example, the dome602may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The dome602may be a solid dome. The dome602may have an arcuate shape at a first surface and/or a second surface. The first surface may be an inner surface. For example, the first surface may face the interior cavity604. The hub610may be disposed in a center of the detector window600. The hub610may be a column. In certain embodiments, the hub610may have a hollow portion. The aperture612may be formed through the hub610. The one or more spokes608may extend radially outward from the hub610. Each of the one or more spokes608may be a wall. The one or more spokes608may be coupled to the first, or inner, surface of the dome602. The one or more spokes608may support the dome602from wellbore pressure exterior to the formation density logging tool. The second surface may be an outer surface. For example, the second surface may face away from the interior cavity604. In some embodiments, the interior cavity604may be filled with a material. The interior cavity604may include a plurality of hollow portions disposed between the one or more spokes608.

With the preceding in mind,FIGS.7A and7Bdepict a schematic diagram and a schematic cross section diagram of a detector window700for a formation density logging tool having a dome702and a collimating aperture704, in accordance with an embodiment. The detector window700may be disposed in a recess of a formation density logging tool, such as formation density logging tool100inFIG.1. The detector window700may include the dome702, the collimating aperture704, a set of flanges706, a collimating wall708, an interior wall710, and one or more apertures712. The detector window700may be circular. Each flange of the set of flanges706may receive an elastomeric O-ring. The elastomeric O-ring may seal against the set of flanges706and a recess of the housing of the formation density logging tool. The elastomeric O-ring may prevent entry of wellbore fluids into an interior of the housing of the formation density logging tool. In certain embodiments, the detector window700may be welded and/or brazed in the recess of the housing of the formation density logging tool.

The dome702may be an exterior dome. For example, the dome702may face outwards from the formation density logging tool and/or towards a geological formation when the formation density logging tool is deployed in a wellbore. The dome702may be a solid dome. The dome702may have an arcuate shape at a first surface702A and/or a second surface702B. The first surface702A may be an inner surface. For example, the first surface702A may face the collimating window704. The second surface702B may be an outer surface. For example, the second surface702B may face away from the collimating window704. The collimating window704may collimate photons traveling through the detector window700in a diagonal direction. The collimating window704may be disposed between adjacent collimating walls708. The collimating wall708may be disposed between the first surface702A of the dome702and the interior wall710. The collimating wall708may support the dome702from wellbore pressure exterior to the formation density logging tool. In some embodiments, the collimating window704may be filled with a material. For example, the collimating window704may be filled by inserting a material through the one or more apertures712. The one or more apertures712may be formed through the interior wall710. The interior wall710may face towards an interior of the formation density logging tool.

Any of the detector windows200,300,400,420,500,600,700may be formed by an additive manufacturing process. An additive manufacturing process, sometimes referred to as “3D printing,” is the manufacturing of an object by the deposition of layers of material (e.g., one layer on top of another) until the completed object is formed. An additive manufacturing process may allow the formation of internal support structures, such as inFIGS.3B,4B,4D,5B,6B, and7B. In some embodiments of an additive manufacturing process, support material may be provided to support layers of the detector window during the layer deposition. In certain embodiments of an additive manufacturing process, the support material may be removed through one or more apertures in the detector window. In certain embodiments, any of the detector windows200,300,400,420,500,600,700may be disposed in a recess of a logging tool with a concave domed surface facing outwards from the logging tool. The internal support structures (e.g.,308,408,428,508,608,708) of the detector windows may provide sufficient support to withstand wellbore pressures while also reducing an effective density of the detector window by using less material than a solid detector window.

With the preceding in mind,FIG.8illustrates a formation density logging tool800having one or more window inserts814. The formation density logging tool800may include a first housing802, one or more detector windows804, an external shield806, one or more detectors including a photomultiplier808and a scintillator810, a collimator812, and one or more window inserts814.

Each of the one or more detectors may include a scintillator810that absorbs the photons and emits light based on the energy of the absorbed photons. For example, each emission of light may count as a detected photon (e.g., thereby adding one to a count rate of the detector). Each of the one or more detectors may also include a photomultiplier808operatively coupled to the scintillator810to detect the light emitted by the scintillator810. The photomultiplier808may output an electrical signal from the detected light of the scintillator. Processing of the electrical signals from the photomultiplier808may be performed at a data processing system at the surface and/or at a data processing system within the BHA. The collimator812may collimate scattered photons towards the one or more detectors. The collimator812may extend from the scintillator810to one of the one or more windows804. The collimator812may have a central axis extending centrally through the length of the collimator from the scintillator810to one of the one or more detector windows804. The collimator812may extend at least partially through an interior of the first housing802. The collimator812may extend at least partially through one of the one or more window inserts814.

The one or more detector windows804may be at least partially disposed in one or more recesses of the first housing802. Further, the one or more detector windows804may be at least partially disposed in one or more recesses of the external shield806. The one or more detector windows804may be capable of withstanding high wellbore pressures. For example, the one or more detector windows804may be capable of withstanding at least seventy MPa. The one or more detector windows804may be formed of a material having a small photoelectric cross section. For example, the one or more detector windows804may be formed of a material having a low atomic number. For example, the one or more detector windows may be formed of a material having an atomic number less than twenty-three. The one or more detector windows804may be formed of a material having a small Compton cross section. For example, the one or more detector windows804may be formed of a material having a low density. For example, the one or more detector windows804may be formed of a material having a density less than five grams per cubic centimeter. In certain embodiments, the one or more detector windows804may be formed of at least one of beryllium, titanium, an alloy of beryllium, an alloy of titanium, a carbon composite, a layered aluminum structure, or any combination thereof. The one or more detector windows804may be coupled to the first housing802. For example, the one or more detector windows804may be welded, brazed, sealed with elastomeric materials, or any other suitable form of sealing.

The one or more window inserts814may extend the collimator812from the scintillator810to one of the one or more detector windows804. The one or more window inserts814may be formed of a material having a high density. For example, the one or more window inserts814may be formed of a material having a density of at least eight grams per cubic centimeter. The one or more window inserts814may be formed of a material having a high atomic number. For example, the one or more window inserts814may be formed of a material having an atomic number of at least twenty-three. In certain embodiments, each of the one or more window inserts814may include a plurality of parts. The one or more window inserts814may shield the scintillator810from photons traveling in a particular direction. The one or more window inserts814may prevent a first portion of photons travelling in a particular direction from entering the collimator812. For example, the one or more window inserts814may prevent a first portion of photons travelling in a direction substantially deviated from parallel to a central axis of the collimator812. For example, the direction may be greater than five degrees from parallel to the central axis of the collimator812. The one or more window inserts814may permit a second portion of photons travelling in a direction substantially parallel to the central axis of the collimator812. For example, the one or more window inserts814may permit a second portion of photons travelling in a direction within five degrees of parallel to the central axis of the collimator812.

FIG.9depicts a schematic cross section diagram of a window insert900having a collimation window904, in accordance with an embodiment. The window insert900may be disposed in a detector window of a formation density logging tool, such as detector window804inFIG.8. The window insert900may be formed of a material having a high density. For example, the window insert900may be formed of a material having a density of at least eight grams per cubic centimeter. The window insert900may be formed of a material having a high atomic number. For example, the window insert900may be formed of a material having an atomic number of at least twenty-three. In certain embodiments, the window insert900may include a plurality of parts, such as first part902A and second part902B. The window insert900may prevent photons from entering the detector in a particular direction. For example, the window insert900may scatter and/or absorb any photon not travelling through the collimation window904. The collimation window904may extend through the window insert900. The collimation window904may be disposed between the first part902A and second part902B. In certain embodiments, the collimation window904may be filled with a material. The collimation window904may permit photons to travel from the geological formation through the collimation window904and to the detector.

FIG.10depicts a schematic cross section diagram of a window insert1000having an aperture1004, in accordance with an embodiment. The window insert1000may be formed of a material having a high density. For example, the window insert1000may be formed of a material having a density of at least eight grams per cubic centimeter. The window insert1000may be formed of a material having a high atomic number. For example, the window insert1000may be formed of a material having an atomic number of at least twenty-three. In certain embodiments, the window insert1000may be formed from a single part1002. The window insert1000may prevent photons from entering the detector in a particular direction. For example, the window insert1000may scatter and/or absorb any photon not travelling through the aperture1004. The aperture1004may extend through the window insert1000. In certain embodiments, the aperture1004may have an oval shape. In some embodiments, the aperture1004may have a circular shape. The aperture1004may permit photons to travel from the geological formation through the aperture1004and to the detector.

FIG.11depicts a schematic cross section diagram of a formation density logging tool1100having one or more window inserts1114, in accordance with an embodiment. The formation density logging tool1100may include a first housing1102, one or more detector windows1104, an external shield1106, one or more detectors including a photomultiplier1108and a scintillator1110, a collimator1112, and one or more window inserts1114.

Each of the one or more detectors may include a scintillator1110that absorbs the photons and emits light based on the energy of the absorbed photons. For example, each emission of light may count as a detected photon (e.g., thereby adding one to a count rate of the detector). Each of the one or more detectors may also include a photomultiplier1108operatively coupled to the scintillator1110to detect the light emitted by the scintillator1110. The photomultiplier1108may output an electrical signal from the detected light of the scintillator. Processing of the electrical signals from the photomultiplier1108may be performed at a data processing system at the surface and/or at a data processing system within the BHA. The scintillator1110may be disposed adjacent one of the one or more windows1104. The collimator1112may collimate scattered photons towards the one or more detectors. The collimator1112may extend from the scintillator1110to one of the one or more windows1104. The collimator1112may have a central axis extending centrally through the length of the collimator1112from the scintillator1110to one of the one or more detector windows1104.

The one or more detector windows1104may be at least partially disposed in one or more recesses of the first housing1102. Further, the one or more detector windows1104may be at least partially disposed in one or more recesses of the external shield1106. The one or more detector windows1104may be capable of withstanding high wellbore pressures. For example, the one or more detector windows1104may be capable of withstanding at least seventy MPa. The one or more detector windows1104may be formed of a material having a small photoelectric cross section. For example, the one or more detector windows1104may be formed of a material having a low atomic number. For example, the one or more detector windows may be formed of a material having an atomic number less than twenty-three. The one or more detector windows1104may be formed of a material having a small Compton cross section. For example, the one or more detector windows1104may be formed of a material having a low density. For example, the one or more detector windows1104may be formed of a material having a density less than five grams per cubic centimeter. In certain embodiments, the one or more detector windows1104may be formed of at least one of beryllium, titanium, an alloy of beryllium, an alloy of titanium, a carbon composite, a layered aluminum structure, or any combination thereof. The one or more detector windows1104may be coupled to the first housing1102. For example, the one or more detector windows1104may be welded, brazed, sealed with elastomeric materials, or any other suitable form of sealing.

The one or more window inserts1114may extend the collimator1112from the scintillator1110to one of the one or more detector windows1104. The one or more window inserts1114may be formed of a material having a high density. For example, the one or more window inserts1114may be formed of a material having a density of at least eight grams per cubic centimeter. The one or more window inserts1114may be formed of a material having a high atomic number. For example, the one or more window inserts1114may be formed of a material having an atomic number of at least twenty-three. In certain embodiments, each of the one or more window inserts1114may include a plurality of parts. The one or more window inserts1114may shield the scintillator1110from photons traveling in a particular direction. The one or more window inserts1114may prevent a first portion of photons travelling in a particular direction from entering the collimator1112. For example, the one or more window inserts1114may prevent a first portion of photons travelling in a direction substantially deviated from parallel to a central axis of the collimator1112. For example, the direction may be greater than five degrees from parallel to the central axis of the collimator1112. The one or more window inserts1114may permit a second portion of photons travelling in a direction substantially parallel to the central axis of the collimator1112. For example, the one or more window inserts1114may permit a second portion of photons travelling in a direction within five degrees of parallel to the central axis of the collimator1112.

FIG.12depicts a schematic cross section diagram of a formation density logging tool1200having a first window insert1210for a source1206and a second window insert1216for a detector1212, in accordance with an embodiment. The formation density logging tool1200may include a first housing1202, an external shield1204, the source1206, a source window1208, a first window insert1210, a detector1212, a detector window1214, a second window insert1216, and a collimator1218. The source1206may be a photon source, such as an x-ray generator, a gamma ray generator, a cesium source, or any other suitable source, that emits photons, such as x-rays, gamma rays, or other high-energy photons. High-energy photons may include photons at an energy sufficient to cause at least a portion of the photons to inelastically scatter off elements of the geological formation and to be absorbed by the detector1212(e.g., Compton scattering). In some embodiments, the source1206may emit the photons through a source collimator1209, such that at least some of the photons enter the geological formation. At least some of the photons may interact with the geological formation (e.g., scatter) and may be redirected towards the detector1212. In certain embodiments, the formation density logging tool1200may include one or more detectors. In some embodiments, at least one of the one or more detectors may be a short-spaced detector and at least one of the one or more detectors may be a long-spaced detector located farther from the source1206than the short-spaced detector.

The source1206may be disposed adjacent to the source window1208. The source window1208may be at least partially disposed in a recess of the first housing1202. Further, the source window1208may be at least partially disposed in a recess of the external shield1204. The source window1208may be capable of withstanding high wellbore pressures. For example, the source window1208may be capable of withstanding at least seventy MPa. The source window1208may be formed of a material having a small photoelectric cross section. For example, the source window1208may be formed of a material having a low atomic number. For example, the source window1208may be formed of a material having an atomic number less than twenty-three. The source window1208may be formed of a material having a small Compton cross section. For example, the source window1208may be formed of a material having a low density. For example, the source window1208may be formed of a material having a density less than five grams per cubic centimeter. In certain embodiments, the source window1208may be formed of at least one of beryllium, titanium, an alloy of beryllium, an alloy of titanium, a carbon composite, a layered aluminum structure, or any combination thereof.

The source window1208may include the first window insert1210. In certain embodiments, the first window insert1210may be formed from more than one part. In certain embodiments, the first window insert1210may be formed of a material having a high density. For example, the first window insert1210may be formed of a material having a density of at least eight grams per cubic centimeter. In certain embodiments, the first window insert1210may be formed of a material having a high atomic number. For example, the first window insert1210may be formed of a material having an atomic number greater than twenty-three. The first window insert1210may include a collimator1209. The collimator1209may be disposed through the first window insert1210. The collimator1209may have a central axis extending centrally through the length of the collimator1209from the source1206to the source window1208. The first window insert1210may permit photons to exit the source1206in a direction substantially parallel to the central axis of the collimator1209. For example, photons may exit the source within five degrees of parallel to the central axis of the collimator1209. The first window insert1210may prevent photons from exiting the source in a direction substantially deviated from parallel to the central axis of the collimator1209. For example, the first window insert1210may prevent photons from exiting the source in a direction greater than five degrees from parallel to the central axis of the collimator1209. The first window insert1210may scatter and/or absorb photons travelling in the substantially deviated direction.

The detector1212may include a scintillator that absorbs the photons and emits light based on the energy of the absorbed photons. For example, each emission of light may count as a detected photon (e.g., thereby adding one to a count rate of the detector). Each of the one or more detectors may also include a photomultiplier operatively coupled to the scintillator to detect the light emitted by the scintillator. The photomultiplier may output an electrical signal from the detected light of the scintillator. Processing of the electrical signals from the photomultiplier may be performed at a data processing system at the surface and/or at a data processing system within the BHA. The detector1212may be disposed adjacent to the detector window1214. The collimator1218may collimate scattered photons towards the detector1212. The collimator1218may extend from the detector1212to the detector window1214. The collimator1218may have a central axis extending centrally through the length of the collimator1218from the detector1212to the detector window1214.

The detector window1214may be at least partially disposed in a recess of the first housing1202. Further, the detector window1214may be at least partially disposed in a recess of the external shield1204. The detector window1214may be capable of withstanding high wellbore pressures. For example, the detector window1214may be capable of withstanding at least seventy MPa. The detector window1214may be formed of a material having a small photoelectric cross section. For example, the detector window1214may be formed of a material having a low atomic number. For example, the detector window1214may be formed of a material having an atomic number less than twenty-three. The detector window1214may be formed of a material having a small Compton cross section. For example, the detector window1214may be formed of a material having a low density. For example, the detector window1214may be formed of a material having a density less than five grams per cubic centimeter. In certain embodiments, the detector window1214may be formed of at least one of beryllium, titanium, an alloy of beryllium, an alloy of titanium, a carbon composite, a layered aluminum structure, or any combination thereof. The detector window1214may be coupled to the first housing1202. For example, the detector window1214may be welded, brazed, sealed with elastomeric materials, or any other suitable form of sealing.

The second window insert1216may extend the collimator1218from the detector1212to the detector window1214. The second window insert1216may be formed of a material having a high density. For example, the second window insert1216may be formed of a material having a density of at least eight grams per cubic centimeter. The second window insert1216may be formed of a material having a high atomic number. For example, the second window insert1216may be formed of a material having an atomic number of at least twenty-three. In certain embodiments, the second window insert1216may include a plurality of parts. The second window insert1216may shield the detector1212from photons traveling in a particular direction. The second window insert1216may prevent a first portion of photons travelling in a particular direction from entering the collimator1218. For example, the second window insert1216may prevent a first portion of photons travelling in a direction substantially deviated from parallel to a central axis of the collimator1218. For example, the direction may be greater than five degrees from parallel to the central axis of the collimator1218. The second window insert1216may permit a second portion of photons travelling in a direction substantially parallel to the central axis of the collimator1218. For example, the second window insert1216may permit a second portion of photons travelling in a direction within five degrees of parallel to the central axis of the collimator1218. In certain embodiments, the collimator1218may be formed at a different angle through the second window insert1216. The angle of the collimator1218of the second window insert1216may be different than an angle of the collimator1209of the first window insert1210. The angle of the collimator1218determines a depth of the scanning area1220in the geological formation. A shallower angle relative to a longitudinal axis of the formation density logging tool1200results in a scanning area at a shallower depth. The depth of the scanning area1220may increase up to a maximum depth when the angle of the collimator1218is perpendicular to the longitudinal axis of the formation density logging tool1200.

FIG.13depicts a schematic cross section diagram of a formation density logging tool1300having a window insert, in accordance with an embodiment. The formation density logging tool1300may include a source1302, a detector window1310, a window insert1312, and a detector1314. The source1302may be a photon source, such as an x-ray generator, a gamma ray generator, a cesium source, or any other suitable source, that emits photons, such as x-rays, gamma rays, or other high-energy photons. High-energy photons may include photons at an energy sufficient to cause at least a portion of the photons to inelastically scatter off elements of the geological formation and to be absorbed by the detector1314(e.g., Compton scattering). The source1302emits the photons such that at least some of the photons enter the geological formation. At least some of the photons may interact with the geological formation (e.g., scatter) and may be redirected towards the detector1314. In certain embodiments, the formation density logging tool1300may include one or more detectors. In some embodiments, at least one of the one or more detectors may be a short-spaced detector and at least one of the one or more detectors may be a long-spaced detector located farther from the source1302than the short-spaced detector.

The source1302may emit a first photon which travels along a first path1306. The photon travelling along the first path1306may exit the source and travel through a debris layer1304disposed on the outer surface of the formation density logging tool1300. The debris layer1304may be a layer of particulates formed from drilling mud. The photon travelling along the first path1306may scatter off of a surface of the geological formation and pass through the debris layer1304and a portion of the housing of the formation density logging tool1300. Due to the first path1306not travelling substantially through the geological formation, the corresponding photon carries little information about the geological formation. The window insert1312may prevent the photon travelling along the first path1306from entering the detector1314. For example, the window insert1312may shield the detector from the photon. The window insert1312may scatter and/or absorb the photon travelling along the first path1306.

The source1302may emit a second photon which travels along a second path1308. The photon travelling along the second path may exit the source and travel through the debris layer1304disposed on the outer surface of the formation density logging tool1300. The photon travelling along the second path1308scatters off the geological formation at a first scattering point. The photon travelling along the second path1308continues travelling through the geological formation until reaching a second scattering point at which the photon scatters towards the detector1314. The window insert1312may be configured to permit the photon travelling along the second path1308to enter the detector. The window insert1312may shield the detector1314from photons travelling in a range of directions. For example, the window insert1312may be configured to shield the detector1314from photons travelling in a direction up to seventy degrees from the longitudinal axis of the logging tool1300. The window insert1312may be configured to permit photons travelling in a direction between seventy degrees and one hundred and fifty degrees from the longitudinal axis of the logging tool1300. The window insert1312may be formed of a material having a high density. For example, the window insert1312may be formed of a material having a density of at least eight grams per cubic centimeter. The window insert1312may be formed of a material having a high atomic number. For example, the window insert1312may be formed of a material having an atomic number of at least twenty-three.

FIG.14depicts a schematic cross section diagram of a window insert1400, in accordance with an embodiment. The window insert1400may be disposed in a detector window of a formation density logging tool, such as detector window804inFIG.8. The window insert1400may prevent photons from entering a detector. The window insert1400may be formed of a material having a high density. For example, the window insert1400may be formed of a material having a density of at least eight grams per cubic centimeter. The window insert1400may be formed of a material having a high atomic number. For example, the window insert1400may be formed of a material having an atomic number of at least twenty-three. The window insert1400may include a shield1402. The shield1402may include a plurality of shielding parts. For example, the shield1402may include a first shield part1402A and a second shield part1402B. The first shield part1402A may be disposed on an opposite side of a longitudinal axis1406of a formation density logging tool from the second shield part1402B. The window insert1400may prevent photons from entering a detector in a direction perpendicular to the longitudinal axis1406of the formation density logging tool. In certain embodiments, the window insert1400may prevent photons from entering a detector in a direction up to sixty degrees from perpendicular to the longitudinal axis1406of the formation density logging tool. The window insert1400may prevent photons from entering the detector from a first side adjacent the first shield part1402A and/or a second side adjacent the second shield part1402B. Photons may enter the detector through the opening1404in the window insert1400.

FIG.15depicts a schematic cross section diagram of a window insert1500having a plurality of shield parts1502A,1502B,1502C, in accordance with an embodiment. The window insert1500may be disposed in a detector window of a formation density logging tool, such as detector window804inFIG.8. The window insert1500may prevent photons from entering a detector. The window insert1500may be formed of a material having a high density. For example, the window insert1500may be formed of a material having a density of at least eight grams per cubic centimeter. The window insert1500may be formed of a material having a high atomic number. For example, the window insert1500may be formed of a material having an atomic number of at least twenty-three. The window insert1500may include a shield1502. The shield1502may include a plurality of shielding parts. For example, the shield1502may include a first shield part1502A, a second shield part1502B, and a third shield part1502C. The first shield part1502A may be disposed on an opposite side of a longitudinal axis1506of a formation density logging tool from the second shield part1502B. The window insert1500may prevent photons from entering a detector in a direction perpendicular to the longitudinal axis1506of the formation density logging tool. In certain embodiments, the window insert1500may prevent photons from entering a detector in a direction up to sixty degrees from perpendicular to the longitudinal axis1506of the formation density logging tool. The window insert1500may prevent photons from entering the detector from a first side adjacent the first shield part1502A and/or a second side adjacent the second shield part1502B. The third shield part1502C may prevent photons from entering the detector at an angle up to seventy degrees from the longitudinal axis of the formation density logging tool. Photons may enter the detector through the opening1504in the window insert1500.

While the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the present disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the following appended claims.

The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).