GB2586649A

GB2586649A - Pressure cell systems for use with drilling fluid

Info

Publication number: GB2586649A
Application number: GB1912561.6A
Authority: GB
Inventors: Clarke Andrew; Bailey Louise; Alice Gilchrist Jamie Elizabeth
Original assignee: Schlumberger Technology BV
Current assignee: Schlumberger Technology BV
Priority date: 2019-09-02
Filing date: 2019-09-02
Publication date: 2021-03-03
Anticipated expiration: 2039-09-02
Also published as: GB201912561D0; GB2586649B

Abstract

A pressure cell 102 has an internal cavity 110 containing drilling fluid 112, 113. The internal cavity 110 is illuminated by a light source 104 and optical data collected by a sensor 106 and processed by a controller 108 to determine a property of the drilling fluid 112, 113, such as the distance 121 between a disperse phase 113 of the drilling fluid and an optical sensor 106, or the thickness 125 of a continuous phase layer 113a of the drilling fluid. In an embodiment, the optical property is diffuse reflection. The controller 108 may determine when the disperse phase 113 separates a threshold amount from the continuous phase 112. The pressure cell 102 may include an opening 114 covered by a cover 115, with a cover bore (136, fig 2) or a window (306, fig 4) to allow light through the cover 115 to illuminate the drilling fluid 112,113. The controller 108 may monitor a change in the received light over time.

Description

Intellectual Property Office Application No. GII1912561.6 RTM Date:8 January 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document: Bluetooth Blu-ray Intellectual Property Office is an operating name of the Patent Office www.gov.uk /ipo

PRESSURE CELL SYSTEMS FOR USE WITH DRILLING FLUID

BACKGROUND

[0001] Drilling fluids may be used in hydrocarbon drilling processes to maintain the structural integrity of the borehole, cool the drill bit, and/or carry cuttings from the drill bit to the surface. Tests may be performed on the drilling fluid to determine properties of the drilling fluid under certain conditions. Some of these tests may include a static aging test or a dynamic aging test.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[0003] Fig. 1 is a schematic representation of a pressure cell system in accordance with a first example of the present disclosure.

[0004] Fig. 2 is an enlarged cross-sectional view of an exemplary cover and an exemplary probe for use with the pressure cell system of Fig. 1.

[0005] Fig. 3 is an enlarged schematic representation of another exemplary cover for use with the pressure cell system of Fig. 1.

[0006] Fig. 4 is an enlarged schematic representation of another exemplary cover including a window for use with the pressure cell system of Fig. 1.

[0007] Fig. 5 is an enlarged cross-sectional view of another exemplary window and another exemplary cover for use the pressure cell system of Fig. 1.

[0008] Fig. 6 is an enlarged schematic representation of the cover having the window of Fig. 4 for use with the pressure cell system of Fig. 1 and including a condenser lens system.

[0009] Fig. 7 is an enlarged schematic representation of the cover having the window of Fig. 4 for use with the pressure cell system of Fig. 1 and including an optical isolator.

[0010] Fig. 8 is a flowchart depicting a method for determining a property of drilling fluid, according to one or more examples of the present disclosure.

DETAILED DESCRIPTION

[0011] Illustrative examples of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0012] Further, as used herein, the article "a" is intended to have its ordinary meaning in the patent arts, namely "one or more." Herein, the term "about" when applied to a value generally means within the tolerance range of the equipment used to produce the value, or in some examples, means plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise expressly specified. Further, herein the term "substantially" as used herein means a majority, or almost all, or all, or an amount with a range of about 51% to about 100%, for example. Moreover, examples herein are intended to be illustrative only and are presented for discussion purposes and not by way of limitation.

[0013] The examples disclosed herein relate to pressure cell systems for use with drilling fluid and, specifically, for use with static aging tests. Static aging tests may involve, for example, housing drilling fluid in a pressure cell for seven days, during which the drilling fluid is heated to a threshold temperature and exposed to a threshold pressure. Other time periods may prove suitable. During the seven day period, changes to the drilling fluid may occur. For example, a disperse phase of the drilling fluid may separate from a continuous phase of the drilling fluid. The pressure cell systems disclosed may include one or more sensors that monitor the drilling fluid in situ during the static aging test. By monitoring the drilling fluid and any changes thereto in real time, an operator may terminate the static aging test before the seven days lapse, if desired. By allowing for the static aging test to be terminated before seven days, static aging tests may be performed on additional drilling fluid samples without additional resources (e.g., equipment) being utilized.

[0014] Referring now to the drawings, Fig. 1 is a schematic representation of a pressure cell system 100 in accordance with a first example of the present disclosure. The pressure cell system 100 is adapted to determine a property of drilling fluid in situ during a static aging test (aging cell test). In an example, the property includes a state of a continuous phase of the drilling fluid and/or a state of a disperse phase of the drilling fluid. Specifically, the pressure cell system 100 may be adapted to dynamically determine when the disperse phase of the drilling fluid settles and/or separates from the continuous phase (e.g., an oil layer) of the drilling fluid. Using the disclosed examples, the pressure cell system 100 may determine when the disperse phase begins to coalesce, causing a change in the density of the drilling fluid, referred to as "sag." The change identified may allow the performance of the drilling fluid to be compared to another drilling fluid. For example, a first drilling fluid may be considered to perform better than a second drilling fluid if the pressure cell system 100 identifies the first drilling fluid separating into two layers (a continuous phase layer and a disperse phase layer) after five days and identifies the second drilling fluid separating into the two layers after two days.

[0015] In the example shown, the pressure cell system 100 includes a pressure cell 102, a light source 104, an optical sensor 106, and a controller 108. The pressure cell system 100 may also include a heater 109. The heater 109 may be adapted to heat the pressure cell 102 during, for example, the static aging test.

[0016] The pressure cell 102 includes an internal cavity 110 that is adapted to contain drilling fluid 111. The drilling fluid 111 is shown as including two phases, a continuous phase 112 forming a first layer 112a and a disperse phase 113 forming a second layer 113a. The continuous phase 112 may be relatively transparent. Prior to separating into the two layers shown, the drilling fluid 111 may be an emulsion including barite. The drilling fluid 111 may be an oil based drilling fluid, a water based drilling fluid, or any other suitable drilling fluid. However, depending on the type of drilling fluid used, the pressure cell system 100 may differently interpret any associated data when determining a property of the fluid, for example.

[0017] Those of skill in the relevant art, upon reading this disclosure, will realize that the teachings may be applied to monitor other types of fluids. For example, tests may be performed on other types of sedimenting fluids, including but not limited to fluids containing cement. When the pressure cell 102 contains cement, the cement may be monitored to detect a sediment layer separating from a water layer. When performing tests on cement, it may not be necessary to heat and/or pressurize the pressure cell 102, and the amount time to perform testing may be less (e.g., hours) compared to the static aging test.

[0018] In the example shown, the pressure cell 102 defines an opening 114 that is covered by a cover 115. The cover 115 may be coupled to a body 116 of the pressure cell 102 in a manner that allows the pressure cell 102 to be pressurized to a threshold pressure and exposed to a threshold temperature. The cover 115 may be coupled to the body 116 via a threaded connection and/or another fastener.

[0019] The light source 104 is arranged to illuminate the drilling fluid 111 contained in the internal cavity 110. In one example, the light source 104 may be arranged to emit a diverging (uncollimated) beam of light and/or modulated light. Other light forms may prove suitable. When the drilling fluid 111 is an oil based drilling fluid, the light source 104 may emit light having a wavelength of approximately 850 nanometers (nm). When the drilling fluid 111 is a water based drilling fluid, the light source 104 may emit light having a wavelength of approximately 1450 nm. Other wavelengths may prove suitable.

[0020] In the example shown, the light source 104 is operatively coupled a probe 118. The probe 118 may be a diffuse reflection probe, a glass fiber probe sheathed within stainless steel, or a fiber-optic probe including a fiber-optic bundle. Other probes may prove suitable. The probe 118 is preferably orientated to allow a central probe axis 119 to be substantially perpendicular to a reflective surface 120 of the drilling fluid 111. The central probe axis 119 may be substantially parallel and/or coaxial to a longitudinal -central axis of the pressure cell 102. Thus, in the illustrated example, the probe 118 points vertically downward. However, the probe 118 may be differently oriented. For example, the probe 118 may be oriented such that the central probe axis 119 is between 0 and less than 90° relative to the longitudinal central axis of the pressure cell 102. However, other angles may prove suitable. The probe 118 is adapted to enable the light source 104 to illuminate the drilling fluid 111.

[0021] While the pressure cell system 100 of Fig. 1 includes one probe 118 at the top of the pressure cell 102, additional probes 118 may be provided. For example, an additional probe may be disposed at the bottom of the pressure cell 102 facing upward toward the cover 115 and having an axis substantially parallel to the central probe axis 119 and/or the longitudinal-central axis of the pressure cell 102. Additionally or in other examples, one or more probes 118 may be positioned along a height of the pressure cell 102 or on the top of the pressure cell 102. The probes 118 may operate at the same or similar wavelengths or may operate at different wavelengths. One or more of the probes 118 may be mounted horizontally or mounted vertically. The same or different types of probes may be used.

[0022] The light emitted by the light source 104 onto the drilling fluid 111 generates diffuse reflections and specular reflections. The reflections may be directed toward the cover 115 and, thus, the probe 118. Specular reflections sensed by the probe 118 and/or the optical sensor 106 may be used to determine the state of the drilling fluid 111 and, more specifically, a distance 121 between a face 122 of the probe 118 and an upper surface 123 of the disperse phase 113, for example. However, determining the distance 121 based on specular reflections may have high sensitivity and, thus, prone to error. As a result, the pressure cell system 100 may be adapted to deter or prevent specular reflection from passing to the probe 118 and, thus, being sensed at the optical sensor 106. For example, the probe 118 may be arranged to deter the specular reflections from reaching the probe 118.

[0023] The diffuse reflections may be used by the pressure cell system 100 to determine the state of the drilling fluid 111. Thus, the pressure cell system 100 may be adapted to allow diffuse reflections to pass to the probe 118 and, thus, be sensed by the optical sensor 106.

[0024] The optical sensor 106 is arranged to generate light data associated with the drilling fluid 111. For example, the optical sensor 106 may generate one or more signals (e.g., light data) associated with light and/or the diffuse reflection that is received by the probe 118 and the optical sensor 106. The light and/or diffuse reflection received may be amplified and measured. The optical sensor 106 may be an electro-optical sensor such as a photodiode. However, any type of sensor may be used that is adapted to, for example, convert light, or a change in light, into an electronic signal. Other sensors that may be used include sensors that measure distance using confocal methods and/or sensors that measure distance using a position sensitive detector, a light beam, and a specular reflection position. If the light emitted by the light source 104 is modulated, the modulated signal may be detected using the optical sensor 106 to improve a signal-to-noise ratio. In such examples, modulation mark-space ratio may be used when determining, for example, the property of the drilling fluid 111. Other sensors may prove suitable.

[0025] In the example shown, the optical sensor 106 is also operatively coupled to the probe 118. Thus, the probe 118 is a bifurcated probe or a bifurcated fiber-optic probe having a first portion associated with the light source 104 and a second portion associated with the optical sensor 106. The probe 118 is adapted to enable the optical sensor 106 to receive / detect the diffuse reflections and thereafter generate the light data associated with the drilling fluid 111.

[0026] The pressure cell system 100 includes a mirror 124. The mirror 124 may direct the light received at the probe 118 to the optical sensor 106. In another example, the mirror 123 may be excluded.

[0027] The controller 108 is adapted to process the light data to determine a property of the drilling fluid 111. The light data may include one or more signals generated by the probe 118 that is proportional to the diffuse reflections and associated with a property of the drilling fluid 111. The property of the drilling fluid 111 may include the drilling fluid 111 being an emulsion, the drilling fluid 111 including a continuous phase layer, the drilling fluid 111 including a disperse phase layer, etc. Processing the light data may allow the controller 108 to determine diffuse reflection / light over time and to identify a change of the diffuse reflection / light. A change in the disperse reflection / light may indicate that the disperse phase 113 is settling toward the bottom of the pressure cell 102. The change may be an increase in a diffuse reflectivity value or a decrease in a diffuse reflectivity value. In an example, the controller 108 is adapted to generate an alert accessible by an operator when a change in the disperse reflections and/or the light received satisfies a threshold amount indicative of the disperse phase 113 separating a threshold amount from the continuous phase 112.

[0028] In an example, processing the light data may allow the controller 108 to determine a change in a height (distance) 125 of the disperse phase 113 of the drilling fluid 111. In an example, an amount of light arriving back at the optical sensor 106 may be proportional to the inverse square of a thickness 128 of the continuous phase 112 and, thus, a distance to the upper surface 123 of the disperse phase 113 of the drilling fluid 111. A change in the distance between the face 122 of the probe 118 and the upper surface 123 of the disperse phase 113 of the drilling fluid 111 is associated with the thickness 128 of the continuous phase 112.

[0029] Equations 1 and 2 may be used to determine the height 124 of the disperse phase 113 as a function of time, where ft represents the height 124, t represents time. Equation 1 is used for t < td and Equation 2 is used for t > td.

[0030] Equation 1: h= ho [0031] Equation 2: t td h (ho -h-)exp( (-) )+ [0032] Equation 3 can be used to generate a graph representing the height 124 of the disperse phase 113 over time. Specifically, Equation 3 represents the initial slope, ?(It, of the curve at td, where, 110 -h, represents the thickness (e.g., a final thickness) 128 of the continuous phase 112, the slope of the curve is associated with the change in the height 124 over time, and At = t -td. Thus, the initial slope is inversely related to a rate of collapse of the disperse phase 113 and is proportional to the thickness 128 of the continuous phase 112. The larger the slope, the greater the sag of the drilling fluid 111 and the greater the mass density of the drilling fluid 111.

[0033] Equation 3: oh n(h -h0,) (At V2 (h0 -lice) Oat At r for n = 1, At -) 0 [0034] In another example, the controller 108 is adapted to determine a diffuse reflectivity of the reflective surface 121 of the drilling fluid 111. The diffuse reflectivity of the drilling fluid 111 may be associated with a state of the drilling fluid 111. When the drilling fluid 111 is an emulsion (e.g., a first state), the diffuse reflectivity of the drilling fluid 111 may be a larger value and, when the drilling fluid 111 includes two layers (e.g., a second state) as shown in Fig. 1, the diffuse reflectivity of the drilling fluid 111 may be a lesser value.

[0035] Equations 4 -8 may be used to determine the diffuse reflectivity of the drilling fluid 111. Equation 4 represents an intensity profile, 1(r), of light emitted from the light source 104 at the probe 118 having an assumption that the light emitted has a Gaussian intensity distribution. Referring to Equation 4, r represents a radial distance from a symmetry axis (e.g., the central axis 119), a1 represents a characteristic width of the profile, and 11 represents an intensity of the light at the face 122 of the probe 118.

[0036] Equation 4: /(r) = /027,,, exp (- [0037] Equation 5 represents the scattered intensity, Is., of the light at each point on the reflective surface 121 of the drilling fluid 111, where S is dependent on the scattering and absorption properties of the reflective surface 121.

[0038] Equation 5: Is = 1*S [0039] Equation 6 represents the intensity, /d" , of the diffused light reaching the probe 118 and/or the optical sensor 106 from a distance, r, between a point on the reflective surface 121 and the symmetry axis (e.g., the central axis 119), with the assumption taken that the scattered light is distributed with a Gaussian profile and has a characteristic width, a2.

[0040] Equation 6: r2 Ides = Is 2m 12 exp(-o- 2o-2 2 2)det [0041] Equation 7 represents the total diffused light, lag, reaching the probe 118 and/or the optical sensor 106 from all points on the reflective surface 121.

[0042] Equation 7: -1,tg = .10 2Trr idet. dr [0043] Equation 8 represents substituting Equations 4, 5, and 6 into Equation 7 and the integral being evaluated.

[0044] Equation 8: Idea 27r(a., +GI) [0045] Equation 9 represents the reflectivity, R, of the drilling fluid 111, where d represents a distance 131 between the face 122 of the probe 118 and the reflective surface 121, o-, N ao + aid and o-2 b0 + bid is assumed, A (4 + B = 2(aot + bob') and C = (cq + q), the normalized reflectivity is 1 at d = 0, and it is assumed that ao=b0 and ai=bi then B/A and C/A are related.

[0046] Equation 9: (tot R -de' 27r(A+Bd+Cd2) [0047] Equation 10 represents the measured signal initial slope, where R is the normalized reflectivity and F is a constant associated with optical sensitivity.

[0048] Equation 10: OR OR -F(ho -h") PA( rDd DAt [0049] Equation 11 represents a figure of merit (FOM) with the inclusion of a time delay, td.

Referring to Equation 11, the factor, F, may be determined during calibration and may be associated with a particular sensor (e.g., the optical sensor 106).

[0050] Equation 11: EOM = 2 t312)1 + t \JAL [0051] In the example shown, the controller 108 includes a user interface 132, a communication interface 133, one or more processors 134, and a memory 135 storing instructions executable by the one or more processors 134 to perform various functions including the disclosed examples. The user interface 132, the communication interface 133, and the memory 135 are electrically and/or communicatively coupled to the one or more processors 134.

[0052] In an example, the user interface 132 is adapted to receive input from a user and to provide information to the user associated with the operation of the pressure cell system 100 and/or an analysis taking place. For example, the user interface 132 may display the alert associated with the disperse phase 113 separating a threshold amount from the continuous phase 112. The user interface 132 may include a touch screen, a display, a key board, a speaker(s), a mouse, a track ball and/or a voice recognition system. The touch screen and/or the display may display a graphical user interface (GUI).

[0053] In an example, the communication interface 133 is adapted to enable communication between the pressure cell system 100 and a remote system(s) (e.g., computers) via a network(s). The network(s) may include the Internet, an intranet, a local-area network (LAN), a wide-area network (WAN), a coaxial-cable network, a wireless network, a wired network, a satellite network, a digital subscriber line (DSL) network, a cellular network, a Bluetooth connection, a near field communication (NFC) connection, etc. Some of the communications provided to the remote system may be associated with analysis results, light data, etc. generated or otherwise obtained by the pressure cell system 100. Some of the communications provided to the pressure cell system 100 may be associated with the drilling fluid 111.

[0054] The one or more processors 134 and/or the pressure cell system 100 may include one or more of a processor-based system(s) or a microprocessor-based system(s). In some examples, the one or more processors 134 and/or the pressure cell system 100 includes one or more of a programmable processor, a programmable controller, a microprocessor, a microcontroller, a graphics processing unit (GPU), a digital signal processor (DSP), a reduced-instruction set computer (RISC), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a field programmable logic device (FPLD), a logic circuit and/or another logic-based device executing various functions including the ones described herein.

[0055] The memory 135 can include one or more of a semiconductor memory, a magnetically readable memory, an optical memory, a hard disk drive (HDD), an optical storage drive, a solid-state storage device, a solid-state drive (SSD), a flash memory, a read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), a random-access memory (RAM), a non-volatile RAM (NVRAM) memory, a compact disc (CD), a compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a Blu-ray disk, a redundant array of independent disks (RAID) system, a cache and/or any other storage device or storage disk in which information is stored for any duration (e.g., permanently, temporarily, for extended periods of time, for buffering, for caching).

[0056] Fig. 2 is an enlarged cross-sectional view of an exemplary cover 115 and an exemplary probe 118 for use with the pressure cell system 100 of Fig. 1. In the example shown, the cover 115 defines a cover bore 136. The cover bore 136 may be a through-hole having a circular cross section or another cross section such as, for example, a rectangular cross section. The probe 118 is disposed within the cover bore 136 and is shown extending from an inner surface 137 of the cover 115 to allow the face 122 of the probe 118 to be immediately adjacent or in contact with the drilling fluid 111. Placing the probe 118 adjacent or in contact with the drilling fluid 111 may reduce or prevent a reflection (e.g., specular reflection). In other examples, the face 122 of the probe 118 may be positioned within the drilling fluid 111 to a depth of, for example, 5 millimeters (mm) or may be spaced from the drilling fluid 111 if, for example, specular reflections are used to determine the property of the drilling fluid 111.

[0057] In the example shown and based on the operative coupling between the probe 118 and the light source 104 and the optical sensor 106, the light source 104 is arranged to illuminate the drilling fluid 111 through the cover bore 136. The optical sensor 106 is arranged to generate light data based on light and/or reflections received through the cover bore 136, via the probe 118. Alternatively, the cover 115 may include two cover bores and two probes, with the probes disposed within the corresponding cover bores and operatively coupled to one of the light source 104 or the optical sensor 106. In another example, multiple probes may be provided that are coupled to the light source 104 and the optical sensor 106. Additional light sources and/or optical sensors may be provided.

[0058] In the example shown, the cover bore 136 includes a first diameter portion 138, a second diameter portion 140, and a tapered portion 142 disposed between the first and second diameter portions 138, 140. The probe 118 threadably engages the cover 115 and is disposed within the first diameter portion 138 of the cover bore 136. A nut 144 defining a nut bore 146 is disposed within the second diameter portion 140 of the cover bore 136 and threadably engages the cover 115. A coupling 148 of the probe 118 extends through the nut bore 146. The coupling 148 may be operatively coupled to the light source 104 and/or the optical sensor 106.

[0059] A washer 150 and a seal 152 are disposed within the cover bore 136. The washer 150 is positioned between the seal 152 and the nut 144. So configured, moving the nut 144 in a direction generally indicated by arrow 154, drives the seal 152 into sealing engagement with the tapered surface 142 and an outer surface of the probe 118 via the washer 150 and the nut 144.

[0060] Fig. 3 is an enlarged schematic representation of another exemplary cover 215 for use with the pressure cell system 100 of Fig. 1. The cover 215 has an inward-facing tapered surface 217. The tapered surface 217 is sloped and is adapted to provide an air gap 219 between the reflective surface 121 of the drilling fluid 111 and the cover 215. The air gap 219 may provide space for the drilling fluid 111 to expand during the static aging test during which the pressure cell 102 is heated by the heater 109. The tapered surface 217 may also allow the face 122 of the probe 118 to be positioned immediately adjacent or in contact with the reflective surface 122 of the drilling fluid 111. Positioning the probe 118 immediately adjacent or in contact with the reflective surface 121 of the drilling fluid 111 may reduce specular reflection.

[0061] Fig. 4 is an enlarged schematic representation of another exemplary cover 315 including a window 306 for use with the pressure cell system 100 of Fig. 1. The window 306 may be made of a soda lime glass. So configured, instead of having the probe 118 positioned within the internal cavity 110 and exposed to the pressures contained therein, the light source 104 is arranged to illuminate the drilling fluid 111 through the window 306, via the probe 118, and the optical sensor 106 is arranged to generate light data based on light and/or reflections received through the window 306, via the probe 118.

[0062] The window 306 may be coupled to the cover 315 via, for example, brazing and/or welding, and may be adapted to allow a pressure within the internal cavity 110 to satisfy a higher pressure as compared to the pressure cell 102 in which the window 306 is not provided. Other coupling methods may prove suitable. Because of the ability of the pressure cell 102 of Fig. 4 to be exposed to increased pressures, an air gap between the drilling fluid 111 and the cover 315 may not be provided. Thus, a lower window surface 308 may be in contact with the reflective surface 121 of the drilling fluid 111. While the lower window surface 308 is shown substantially flush with a surrounding lower cover surface 310, in another example, the lower window surface 308 may extend into the internal cavity 110 of the pressure cell 102.

[0063] In the example shown, the cover 315 defines a cover bore 312. The cove bore 312 receives the window 306. The cover bore 312 may also receive the probe 118 (See, Fig. 5). The probe 118 and/or the window 306 may be arranged to reduce reflection therebetween.

[0064] The cover 315 may include an inward extending flange 314 that extends into the cover bore 312. The window 306 may abut against the inward extending flange 314. One or more seals 316 may be provided between the window 306, the inward extending flange 314, and the cover 315. The seals 316 may be 0-rings. In other examples, one or more of the seals 316 may be excluded or additional seals 316 may be provided.

[0065] The window 306 may have a refractive index that is similar to or the same as the drilling fluid 111. The drilling fluid 111 may have a refractive index of approximately 1.47. Providing the window 306 with a similar refractive index as the drilling fluid 111 may reduce Fresnel reflection at the interface between, for example, the lower window surface 308 and the reflective surface 121 of the drilling fluid 111. Additionally or in another example, a refractive index matching grease 318 may be disposed between the face 122 of the probe 118 and the window 306. The matching grease 318 may reduce reflection between the probe 118 and the window 306.

[0066] To determine the reflectivity, R, of the drilling fluid 111 contained in the pressure cell 102 of Fig. 4 including the window 306, Equation 12 may be used instead of Equation 9. Equation 10 may compensate for the window 306. Referring to Equation 12, d, represents a thickness 320 of the window 306 and So represents a component of reflectivity due to the interfaces of the window 306.

[0067] Equation 12:

S

R - So 271-(A+ B(d + d0)+ C(d + [0068] Fig. 5 is an enlarged cross-sectional view of an exemplary window 306 and an exemplary probe 118 for use with the pressure cell system 100 of Fig. 1. In the example shown, the window 306 covers a cover bore 406 and includes a window flange 410 and a window boss 412. The window flange 410 abuts a lower surface 414 of the cover 315. The window boss 412 extends into the cover bore 406 and threadably engages the cover 315. In an example, a tapered NPT thread is provided that is adapted to provide a pressure seal when tightened. A bushing 415 is disposed in the cover bore 406. The bushing 415 includes a first diameter bushing portion 416, a second diameter bushing portion 418, and defines a bushing through hole 420. The bushing 415 may be made of aluminum. Other materials for the bushing 415 may prove suitable.

[0069] The probe 118 is disposed in the bushing through hole 420 and threadably engages the bushing 415. The face 122 of the probe 118 is positioned immediately adjacent an outward facing window surface 422. The matching grease 318 may be positioned between the face 122 of the probe 118 and the outward facing window surface 422.

[0070] A step 424 is formed between the first diameter bushing portion 416 and the second diameter bushing portion 418. The window boss 412 is disposed in a space formed between the second diameter bushing portion 418 and the cover 315 and is shown immediately adjacent or abutting the step 424.

[0071] Fig. 6 is an enlarged schematic representation of the cover 315 having the window 306 of Fig. 4 for use with the pressure cell system 100 of Fig. 1 and including a condenser lens system 504. The condenser lens system 504 is arranged between the window 306 and the light source 104 and, specifically, between the window 306 and the probe 118. The condenser lens system 504 may be adapted to redirect and/or condense the light emitted from the light source 104 to allow a focal point of the light to be close to the reflective surface 121 of the drilling fluid 111. In an example, the condenser lens system 504 includes two lenses having convex sides facing one another. Other arrangements may prove suitable.

[0072] Fig. 7 is an enlarged schematic representation of the cover 315 having the window 306 of Fig. 4 for use with the pressure cell system 100 of Fig. 1 and including an optical isolator 604. The optical isolator 604 is arranged between the window 306 and the optical sensor 106 and, specifically between the window 306 and the probe 118. The optical isolator 604 may include a polarizer and may be adapted to deter or prevent specular reflection from passing to the probe 118 and, thus, being sensed at the optical sensor 106. The optical isolator 604 may be adapted to allow diffuse reflections to pass to the probe 118 and, thus, be sensed by the optical sensor 106.

[0073] Fig. 8 illustrates a flowchart for a method 800 of determining a property of the drilling fluid 111 using the pressure cell system 100 of Fig. 1 or any of the examples disclosed herein. The order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, combined and/or subdivided into multiple blocks.

[0074] The method 800 begins at block 802 by illuminating the drilling fluid 111 contained in the internal cavity 110 of the pressure cell 102. In an example, the one or more processors 134 executing instructions stored in the memory 135 cause the light source 104 to illuminate the internal cavity 110 of the pressure cell 102 and any drilling fluid 111 contained therein. Light data is generated associated with the drilling fluid 111 contained in the internal cavity 110 of the pressure cell 102 (block 804). In an example, the one or more processors 134 executing instructions stored in the memory 135 cause the optical sensor 106 to generate one or more signals (e.g., light data) proportional to light and/or diffuse reflectivity sensed by the optical sensor 106. The light data is processed (block 806). In an example, the one or more processors 134 executing instructions stored in the memory 135 cause the controller 108 to process the light data. In response to the processing of the light data, a property of the drilling fluid 111 is determined (block 808). In an example, the one or more processors 134 executing instructions stored in the memory 135 cause the controller 108 to determine a property of the drilling fluid 111. The property of the drilling fluid 111 may include diffuse reflectively over time and/or may be associated with a change in signals generated by the optical sensor 106 proportional to diffuse reflectivity and/or the light received.

[0075] In accordance with a first example, a pressure cell system for use with drilling fluid includes a pressure cell having an internal cavity and adapted to contain the drilling fluid. The pressure cell system includes a light source arranged to illuminate the internal cavity of the pressure cell and any of the drilling fluid contained in the internal cavity of the pressure cell. The pressure cell system includes an optical sensor arranged to receive light from the light source and to generate light data associated with any of the drilling fluid contained in the internal cavity of the pressure cell. The pressure cell includes a controller adapted to process the light data and to determine a property of the drilling fluid.

[0076] In accordance with a second example, a pressure cell system for use with drilling fluid includes a pressure cell having an internal cavity and adapted to contain the drilling fluid. The pressure cell system includes a diffuse reflection probe facing or in contact with a top surface of any drilling fluid and adapted to generate one or more signals proportional to diffuse reflectivity. The pressure cell system includes a controller adapted to process the one or more signals and to determine one or more properties of the drilling fluid.

[0077] In accordance with a third example, a method includes illuminating, using a light source, drilling fluid contained in an internal cavity of a pressure cell; generating light data, using an optical sensor, associated with the drilling fluid contained in the internal cavity of the pressure cell; processing the light data, using a controller; and in response to the processing, determining, using the controller, a property of the drilling fluid.

[0078] In further accordance with the foregoing first, second and/or third examples, an apparatus and/or method may further include any one or more of the following: [0079] In accordance with one example, the property is associated with a distance between a disperse phase of the drilling fluid and the optical sensor or a thickness of a continuous phase layer of the drilling fluid.

[0080] In accordance with another example, the controller is adapted to process the light data to determine a change in the light received over time.

[0081] In accordance with another example, the light is associated with a thickness of a continuous phase layer of the drilling fluid or a position of an upper surface of a disperse phase layer of the drilling fluid.

[0082] In accordance with another example, the light received by the optical sensor includes diffuse reflections.

[0083] In accordance with another example, the property of the drilling fluid is associated with a disperse phase of the drilling fluid separating from a continuous phase of the drilling fluid.

[0084] In accordance with another example, the controller is adapted to generate an alert when the disperse phase of the drilling fluid separates a threshold amount from the continuous phase of the drilling fluid.

[0085] In accordance with another example, the pressure cell defines an opening and includes a cover. The cover is adapted to cover the opening of the pressure cell.

[0086] In accordance with another example, the cover defines a cover bore, and the light source is arranged to illuminate the drilling fluid through the cover bore.

[0087] In accordance with another example, further including a probe disposed within the cover bore and operatively coupled to the optical sensor and the light source. The probe adapted to enable the light source to illuminate the drilling fluid and for the optical sensor to generate the light data associated with the drilling fluid.

[0088] In accordance with another example, the cover includes an inward-facing tapered surface adapted to provide an air gap between the drilling fluid and the cover.

[0089] In accordance with another example, the pressure cell includes a window. The light source arranged to illuminate the drilling fluid through the window.

[0090] In accordance with another example, the pressure cell defines an opening and includes a cover. The cover defining a cover bore and adapted to cover the opening of the pressure cell. The window covers the cover bore. Further including a probe disposed within the cover bore and operatively coupled to the optical sensor and the light source.

[0091] In accordance with another example, further including refractive index matching grease disposed between a face of the probe and the window.

[0092] In accordance with another example, further including a condenser lens system arranged between the window and the light source.

[0093] In accordance with another example, further including an optical isolator disposed between the window and the optical sensor.

[0094] In accordance with another example, the one or more properties include a state of a disperse phase of the drilling fluid.

[0095] In accordance with another example, the controller is adapted to process the one or more signals to identify when a change in the one or more signals occurs. The change associated with the drilling fluid including two layers.

[0096] In accordance with another example, the diffuse reflection probe is arranged to deter specular reflections from being directed to or received by the diffuse reflection probe.

[0097] In accordance with another example, the determining of the property of the drilling fluid includes determining diffuse reflectively over time.

[0098] In accordance with another example, the property of the drilling fluid is associated with a change in signals proportional to diffuse reflectivity.

[0099] Further, while several examples have been disclosed herein, any features from any examples may be combined with or replaced by other features from other examples. Moreover, while several examples have been disclosed herein, changes may be made to the disclosed examples within departing from the scope of the claims.

[00100] Examples in the present disclosure may also be directed to a non-transitory computer-readable medium storing computer-executable instructions and executable by one or more processors of the computer via which the computer-readable medium is accessed. A computer-readable media may be any available media that may be accessed by a computer. By way of example, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to carry or store desired program code in the form of instructions or data structures and that may be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray® disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers.

[00101] Note also that the software implemented aspects of the subject matter claimed below are usually encoded on some form of program storage medium or implemented over some type of transmission medium. The program storage medium is a non-transitory medium and may be magnetic (e.g., a floppy disk or a hard drive) or optical (e.g., a compact disk read only memory, or "CD ROM"), and may be read only or random access. Similarly, the transmission medium may be twisted wire pairs, coaxial cable, optical fiber, or some other suitable transmission medium known to the art. The claimed subject matter is not limited by these aspects of any given implementation.

[00102] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the disclosure. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the systems and methods described herein. The foregoing descriptions of specific examples are presented for purposes of illustration and description. They are not intended to be exhaustive of or to limit this disclosure to the precise forms described. Obviously, many modifications and variations are possible in view of the above teachings. The examples are shown and described in order to best explain the principles of this disclosure and practical applications, to thereby enable others skilled in the art to best utilize this disclosure and various examples with various modifications as are suited to the particular use contemplated. It is intended that the scope of this disclosure be defined by the claims and their equivalents below.

Claims

CLAIMSWhat is claimed is: 1. A pressure cell system for use with drilling fluid, comprising: a pressure cell having an internal cavity and adapted to contain the drilling fluid; a light source arranged to illuminate the internal cavity of the pressure cell and any of the drilling fluid contained in the internal cavity of the pressure cell; an optical sensor arranged to receive light from the light source and to generate light data associated with any of the drilling fluid contained in the internal cavity of the pressure cell; and a controller adapted to process the light data and to determine a property of the drilling fluid.
2. The pressure cell system of claim 1, wherein the property is associated with a distance between a disperse phase of the drilling fluid and the optical sensor or a thickness of a continuous phase layer of the drilling fluid.
3. The pressure cell system of claim 1, wherein the controller is adapted to process the light data to determine a change in the light received over time.
4. The pressure cell system of claim 3, wherein the light is associated with a thickness of a continuous phase layer of the drilling fluid or a position of an upper surface of a disperse phase layer of the drilling fluid.
5. The pressure cell system of claim 1, wherein the light received by the optical sensor comprises diffuse reflections.
6. The pressure cell system of claim 1, wherein the property of the drilling fluid is associated with a disperse phase of the drilling fluid separating from a continuous phase of the drilling fluid.
7. The pressure cell system of claim 6, wherein the controller is adapted to generate an alert when the disperse phase of the drilling fluid separates a threshold amount from the continuous phase of the drilling fluid.
8. The pressure cell system of claim 1, wherein the pressure cell defines an opening and comprises a cover, the cover adapted to cover the opening of the pressure cell.
9. The pressure cell system of claim 8, wherein the cover defines a cover bore, and wherein the light source is arranged to illuminate the drilling fluid through the cover bore.
10. The pressure cell system of claim 9, further comprising a probe, the probe disposed within the cover bore and operatively coupled to the optical sensor and the light source, the probe adapted to enable the light source to illuminate the drilling fluid and for the optical sensor to generate the light data associated with the drilling fluid.
11. The pressure cell system of claim 8, wherein the cover comprises an inward-facing tapered surface adapted to provide an air gap between the drilling fluid and the cover.
12. The pressure cell system of claim 1, wherein the pressure cell comprises a window, the light source arranged to illuminate the drilling fluid through the window.
13. The pressure cell system of claim 12, wherein the pressure cell defines an opening and comprises a cover, the cover defining a cover bore and adapted to cover the opening of the pressure cell, wherein the window covers the cover bore, further comprising a probe disposed within the cover bore and operatively coupled to the optical sensor and the light source.
14. The pressure cell system of claim 13, further comprising refractive index matching grease disposed between a face of the probe and the window.
15. The pressure cell system of claim 12, further comprising a condenser lens system arranged between the window and the light source.
16. The pressure cell system of claim 12, further comprising an optical isolator disposed between the window and the optical sensor.
17. A pressure cell system for use with drilling fluid, comprising: a pressure cell having an internal cavity and adapted to contain the drilling fluid; a diffuse reflection probe facing or in contact with a top surface of any drilling fluid and adapted to generate one or more signals proportional to diffuse reflectivity; and a controller adapted to process the one or more signals and to determine one or more properties of the drilling fluid.
18. The pressure cell system of claim 17, wherein the one or more properties include a state of a disperse phase of the drilling fluid.
19. The pressure cell system of claim 17, wherein the controller is adapted to process the one or more signals to identify when a change in the one or more signals occurs, the change associated with the drilling fluid including two layers.
20. The pressure cell system of claim 17, wherein the diffuse reflection probe is arranged to deter specular reflections from being directed to or received by the diffuse reflection probe.
21. A method, comprising: illuminating, using a light source, drilling fluid contained in an internal cavity of a pressure cell; generating light data, using an optical sensor, associated with the drilling fluid contained in the internal cavity of the pressure cell; processing the light data, using a controller; and in response to the processing, determining, using the controller, a property of the drilling fluid
22. The method of claim 21, wherein the determining of the property of the drilling fluid comprises determining diffuse reflectively over time.
23. The method of claim 21, wherein the property of the drilling fluid is associated with a change in signals proportional to diffuse reflectivity.