COMPONENTS

INVENTOR(S): DIFOGGIO, Rocco jFIELD OF THE DISCLOSURE

[0001] This disclosure pertains generally to devices and methods for providing shock and vibration protection for downhole devices.

BACKGROUND OF THE DISCLOSURE

[0002] Exploration and production of hydrocarbons generally requires the use of various tools that are lowered into a borehole, such as wireline assemblies, drilling assemblies, measurement tools and production devices (e.g., fracturing tools). Motion sensitive components may be disposed downhole for various purposes, measuring one or more parameters of interest, control of downhole tools, processing data, communication with the surface and storage and analysis of data. Such motion sensitive components often are sensitive to shocks, vibration and other mechanical stresses. For example, a borehole gravimeter may use a delicate spring to enable a gravity measurement, which spring could be broken by shock or vibration prior to its stationary operation at the target depth in a well. Similarly, a subminiature 9-pole mass spectrometer, which is smaller than the size of a thumb, may be made of glass with many glass-to-metal struts supporting structures within its internal vacuum and this mass spectrometer could be broken while the tool that contains it is being transported to a well location or being run into a well before ever being operated downhole.

[0003] In one aspect, the present disclosure addresses the need for enhanced shock and vibration protection for motion sensitive components and other shock and vibration sensitive devices used in a borehole. SUMMARY OF THE DISCLOSURE

[0001] In aspects, the present disclosure provides an apparatus for protecting a motion sensitive component used in a borehole. The apparatus may include an enclosure having a chamber receiving the motion sensitive component, an energy absorbing material at least partially surrounding the chamber, and a force spreading material at least partially surrounding the chamber.

[0002] In aspects, the present disclosure also provides an apparatus that has an enclosure having a chamber receiving the motion sensitive component and a force spreading material at least partially surrounding the chamber. The force spreading material may include colloidal particles dispersed in a liquid and whose viscosity increases with shear rate, wherein the particles have a property selected from at least one of: (i) a size no less than 1 μιτι, (ii) a elongated shape, and (iii) a volume fraction of the colloidal particles in the liquid of at least 30%, and wherein the liquid has a viscosity index of at least 80.

[0004] In aspects, the present disclosure further provides a method for apparatus for protecting a motion sensitive component used in a borehole. The method may include the steps of positioning the motion sensitive device in a chamber of an enclosure; at least partially surrounding the motion sensitive device with a force spreading material; conveying the motion sensitive device into the borehole; and using the motion sensitive device at a location in the borehole wherein an ambient temperature is at least 200 degrees Fahrenheit.

[0005] Examples of certain features of the disclosure have been summarized rather broadly in order that the detailed description thereof that follows may be better understood and in order that the contributions they represent to the art may be appreciated. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] For a detailed understanding of the present disclosure, reference should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein:

FIG. 1 shows a schematic of a well system that may use one protective enclosure according to the present disclosure;

FIG. 2 illustrates one embodiment of an enclosure that uses a force spreading material and an energy absorbing material to protect motion sensitive components;

FIG. 3 illustrates one embodiment of an enclosure that uses a force spreading material adapted for high-temperature applications to protect sensitive components; and

FIG. 4 A illustrates a graph of the relationship between shear rate and viscosity as a volume fraction of particles in a force spreading material vary;

FIG. 4B illustrates a graph of the relationship of viscosity and shear rate for different shapes of particles in a force spreading material; and

FIG. 4C illustrates a graph of the relationship of viscosity and shear rate for different sizes of particles in a force spreading material.

DETAILED DESCRIPTION

[0007] Operation of tools in a downhole environment exposes such tools to sustained and intense shock and vibration events. These events can induce failure, fatigue, and accelerated aging in motion sensitive components used in a work string such as a drill string. In aspects, the present disclosure provides enclosures and related methods for protecting motion sensitive components from the energy associated with such shock events. In embodiments, the present disclosure provides protective enclosures that use dilatants. Dilatants are materials whose viscosity increases with shear rate. The increase in viscosity can be so dramatic that, under the shock of a projectile impact, a putty-like dilatant instantly 'freezes' and behaves like a solid, thus spreading a high local force over the entire area of the dilatant and thereby greatly reducing any pressure (force per unit area) that is felt by any objects being protected behind the dilatant. As discussed in greater detail below, some embodiments combine alternating layers of a force spreading material (e.g. , a dilatant) and an energy absorbing material (e.g., silicone gel) to provide enhanced protection against shock events. Dilatants can be used in military body armor. Silicone gel that is 2 cm thick can prevent a raw egg from breaking when dropped onto it from a height of 60 feet. Other embodiments formulate the dilatant to function in a high temperature environment as is found downhole. Such high-temperature embodiments may be used with or without an energy absorbing layer.

[0008] Referring now to FIG. 1, there is shown one illustrative embodiment of a drilling system 10 utilizing a borehole string 12 that may include a bottomhole assembly (BHA) 14 for directionally drilling a borehole 16. While a land-based rig is shown, these concepts and the methods are equally applicable to offshore drilling systems. The borehole string 12 may be suspended from a rig 20 and may include jointed tubulars or coiled tubing. In one configuration, the BHA 14 may include a drill bit 15, a sensor sub 32, a bidirectional communication and power module (BCPM) 34, a formation evaluation (FE) sub 36, and rotary power devices such as drilling motors 38. The sensor sub 32 may include sensors for measuring near-bit direction (e.g., BHA azimuth and inclination, BHA coordinates, etc.) and sensors and tools for making rotary directional surveys. The system may also include information processing devices such as a surface controller 50 and / or a downhole controller 42. Communication between the surface and the BHA 14 may use uplinks and / or downlinks generated by a mud-driven alternator, a mud pulser and /or conveyed using hard wires (e.g., electrical conductors, fiber optics), acoustic signals, EM or RF. It should be appreciated that motion sensitive components can be present throughout the BHA 14.

[0009] FIG. 2 illustrates an enclosure 100 for protecting a motion sensitive component 102 used in a downhole environment, such as that shown in FIG. 1. In this non-limiting embodiment, the enclosure 100 includes an outer shell 104 and multiple nested shells 106, 108. The diameters of the shells 104, 106, 108 are selected to form annular spaces. An annular space 110 separating the shell 104 and the shell 106 may be filled with an energy absorbing material 116. An annular space 112 separating the shell 106 and the shell 108 may be filled with a force spreading material 118. The innermost shell 108 may include a chamber 114 for receiving the motion sensitive component 102.

[0010] The force spreading material 118 may be any material that acts as a solid at high shear rate and a fluid at low shear rate. Such materials are often referred to as dilatants or "shear thickening fluids", which are defined as fluids whose viscosity increases with the shear rate, which makes them non- Newtonian fluids. Generally, these fluids are composed of particles suspended in a base liquid. Examples of such fluids include, but are not limited to, cornstarch in water, quicksand, viscoelastic liquid silicone, etc. The solid particles are often inexpensive silica or calcium carbonate particles but they could be made of other, more expensive materials such as silicon carbide or diamond grit if one wanted to make the dilatant material more thermally conductive.

[0011] The energy absorbing material 116 may be any material that mechanically or chemically absorbs the kinetic energy associated with a shock / vibration event. Such materials may include liquids or gels such as silicone gel or solids such as elastomeric materials. Common energy absorbing materials exhibit elastomeric or plastic deformation to absorb energy and they may include solid rubber, neoprene, silicone, or various viscoelastic polymers such as polyether-based, polyurethane materials or porous (foam) or structured (hexagonal frame) versions of these materials. Recently, 3D printing with silicone-based ink has been used to make energy absorbing structures whose absorbing properties can be engineered based on their structure. For downhole use, silicone offers the benefit of having a service temperature to 200 C. Note that dilatants can absorb some energy and that some energy absorbing materials have dilatant properties. However, for the purpose of this disclosure, dilatants are defined as materials that are primarily dilatant and energy-absorbing materials are defined as materials that are primarily energy absorbing.

[0012] It should be noted that the enclosure 100 is susceptible to numerous variants. For example, while the enclosure 100 is depicted as tubular, any other shape (e.g. , square, rectangular, etc.) may be used. Also, the shells 104, 106, 108, may be concentrically or eccentrically aligned. Further, while the enclosure 100 is shown as only encircling the motion sensitive component 102, other embodiments may fully enclose the motion sensitive component 102 on all sides. Other variants may be to use more than one layer of each type of material, e.g. , one energy absorbing layer and two force spreading layers, two of each type of layers, etc. Such multiple layers may or may not be alternating. It should also be noted that the sequence of layers may be reversed; i. e., the outer layer may be the force spreading layer and the inner layer may be the energy absorbing layer.

[0013] Referring to FIG. 3, there is shown another embodiment of an enclosure 140 in accordance with the present disclosure. In this non-limiting embodiment, the enclosure 140 includes an outer shell 144 and an inner shell 146. The diameters of the shells 144, 146 are selected to form annular spaces. An annular space 150 separating the shell 144 and the shell 146 may be filled with a force spreading material 152. The inner shell 146 may include a chamber 152 for receiving the motion sensitive component 102.

[0014] The force spreading material 152 may be formulated specifically for use in a relatively hot downhole environment. For purposes of the present disclosure, temperatures in excess of about 200 degrees Fahrenheit is considered "hot." The dilatant effect is associated with surface chemistry of colloidal particles in dispersion. Generally speaking, the dilatant effect tends to diminish in hot ambient environments. Embodiments of the present disclosure enhance the ability of force spreading material 152 to function in such hot environments by adjusting one or more characteristics of particles suspended in a fluid making up the force spreading material 152. These characteristics include, but are not limited to, particle size, shape, and distribution.

[0015] For hot environment use, the viscosity versus temperature behavior of the base fluid of a dilatant is also important. Usually, the viscosity of a polymer liquid depends strongly on temperature, which can seriously affect its shear-thickening responses when it is the base fluid into which particles are mixed. That is, the critical shear rate for the onset of shear thickening decreases with decreasing temperature and vice-versa. More specifically, the critical shear rate is inversely proportional to the viscosity of the base fluid into which the particles are mixed. Therefore, for maximum stability of a dilatant at high temperatures, it is best to use a base fluid whose viscosity changes as little as possible with temperature.

[0016] Viscosity Index (VI) is a scale created for automobile motor oils where the higher the viscosity index the less the oil's viscosity decreases with increasing temperature. A viscosity index of 80 to 110 is considered "high" and above "110" is considered "very high". Various silicone liquids (dimethyl-, phenyl-, or halogenated) have a VI of 200 - 650 and perfluoropolyether (PFPE) has a VI of 100 - 350, polyglycols have a VI above 200, and polyalphaolefins (PAOs) have a VI of 135 - 155. For a downhole dilatant, it is best to use a high temperature base fluid having a high VI.

[0017] Referring to FIGS. 4A-C, there are shown graphs illustrating how particle characteristics can influence behavior of a dilatant. FIGS. 4A-C depict information reported in "A Novel Approach for Armor Applications of Shear Thickening Fluids in Aviation and Defense Industry," Kushan et al., May 2014. [0018] FIG. 4A illustrates the effect of volume fraction of particles on the change of viscosity versus shear rate. Shear rate is along the "X" axis and viscosity is along the "Y" axis. Each line represents a dilatant with a unique volume fraction in a base fluid. Line 160 has the lowest volume fraction of particles and line 162 has the highest volume fraction of particles. Each line from 160 to 162 has an incrementally higher volume fraction of dilatant. As can be seen, the dilatants with the lower volume fractions, e.g., line 160, have little change in viscosity as shear rate increases whereas dilatants with higher volume fractions, e.g., line 162, exhibits an increase in viscosity after the shear rate passes a particular threshold. By way of illustration, line 160 may represent a volume fraction of 25% and line 162 may represent a volume fraction of 45%. Desirable volume fractions may be at least 25%, at least 30%, at least, 40%, or at least 45%.

[0019] FIG. 4B illustrates the effect of particle shape on the change of viscosity versus shear rate. Shear rate increases on an "X" axis and viscosity increases on a "Y" axis. Each line represents a dilatant with a differently shaped particle. Line 170 represents spheroid particles, line 172 represents ovoid particles, line 174 represents platen particles, and line 176 represents rod / cylindrical particles. As can be seen, the dilatants having spherical particles, e.g., line 170, have little change in viscosity as shear rate increases whereas dilatants with elongated particles, e.g., lines 174, 176, exhibits a steady increase in viscosity as shear rate increases. By "elongated," it is meant that a body has an asymmetric shape or has different dimensions along different axes. The dimensional difference may be one dimension at least 10%, 25%, or 50% greater than another dimension.

[0020] FIG. 4C illustrates the effect of particle size on critical shear rate; i.e., the shear rate at which viscosity changes. Particle size increases along the "X" axis and critical shear rate increases along the "Y" axis. As can be seen, an increase in particle size decreases the critical shear rate. For instance, points 180 representing particles of having the largest size have a lower critical shear rate than points 182 representing particles having the smallest size. Thus, shear thickening can be achieved at lower shear rates by minimizing or eliminating relatively smaller particles from a dilatant. For example, particles may be selected to be no less than 1 μηι. Alternatively, a dilatant may formulate to have at least 60%, 70%, 80%, or 90% of particles greater than 1 μηι.

[0021] In other embodiments, dilatants for high-temperature applications may use a fluid selected for such environments. For example, suitable liquids may be liquids that maintain at least 70%, 80%, or 90% of their viscosity at temperatures in excess of 200 degrees Fahrenheit.

[0022] Thus, by appropriately selecting particle properties and fluid properties, a dilatant may be temperature resistant; i.e. , retain a viscosity increase with shear rate even in "hot" ambient environments. This may be done by lowering the value of the shear rate at which shear thickening first occurs, which is the onset value.

[0023] While the present teachings have been discussed in the context of hydrocarbon producing wells, it should be understood that the present teachings may be applied to geothermal wells, groundwater wells, subsea analysis, etc.

[0024] Also, any conveyance device, other than a drill string, may be used to convey motion sensitive devices protected according to the present disclosure along a borehole. Exemplary non-limiting conveyance devices include casing pipes, wirelines, wire line sondes, slickline sondes, drop shots, downhole subs, BHA's, drill string inserts, modules, internal housings and substrate portions thereof, self-propelled tractors.

[0025] While the foregoing disclosure is directed to the one mode embodiments of the disclosure, various modifications will be apparent to those skilled in the art. It is intended that all variations be embraced by the foregoing disclosure.