MXPA98001278A - System of circulation of mud to the fund of the perforac - Google Patents

Abstract

The present invention relates to a downhole tool, constructed to be suspended in a well by pipe, includes a housing, a circulation piston, a deflection member and a pressure compensation system. The housing defines a flow chamber in open fluid communication with the interior of the pipe, a bypass port for fluid flow between the flow chamber and the well, a mud chamber in open communication with the well, and a sealed chamber separated from the flow chamber through a sealed interface. The circulation piston separates the flow and mud chambers and is arranged for movement between a first bypass port blocking position and a second bypass port exposure position in response to the pressure in the flow chamber. The diverting member deflects the circulation piston to its first position and the pressure compensation system limits the pressure difference between the flow and seal chambers, thereby limiting the pressure difference across the sealed interface. The tool has particular application to tools, eg, well-logging tools, adapted to be connected at the bottom of the well to a borehole cable connector that is pumped down the well. It also describes the methods of u

Description

MUD CIRCULATION SYSTEM TO DRILL FUND This invention relates to instruments in a probing cable equipped with remotely coupled electrical connectors for use in oil wells. Once an oil well has been drilled, it is customary to make a log of certain sections of the area with electrical instruments. These instruments are sometimes called instruments of the "sounding cable", since they communicate with the unit of diag- raphy, on the surface of the well, through an electric cable with which they are deployed. In vertical wells, instruments are often simply lowered to the bottom of the well on the probe cable. In horizontal wells or very deviated, however, gravity is often insufficient to move the instruments to the depths to be recorded. In these situations, it is sometimes necessary to push the instruments along the well with a drill pipe. The logging on a drilling cable with a drill pipe can be difficult, however, due to the presence of the cable. It is uncomfortable and dangerous to extend the electrical cable through the entire drill pipe before lowering the instruments into the well. For this reason some deployment systems have been developed, such as Schlumberger's difficult-well logging system (SDPD), with which the electrical connection between the instruments and the cable at the bottom of the borehole is made afterwards. of descending the instruments to the bottom. In these systems, electrical instruments are easily deployed with standard drilling pipes, and then the cable is introduced into the drill pipe and connected. After making the graph, the cable can be easily uncoupled from the diag- nostic probe and removed before removing the probe. The SDPD is very effective and has been widely recognized commercially. In the SDPD and other systems, the cable is remotely connected to the instruments with a connector at the bottom of the hole. One half of this connector is attached to the instruments and lowered into the well-in the drill pipe. The other half of the connector is attached to the end of the cable and is pumped along the drill pipe with a flow of sludge from the open holes in the bottom of the drill pipe and into the interior. of the perforation. The connector is sometimes called a "wet connector" because the connection is made in the flow of drilling mud under conditions that challenge the reliability of an electrical connection. To further complicate the use in the field of such systems, occasional surges of well fluids may be introduced into the drill pipe, through the sludge circulation holes, near the bottom of the pipe, separating the connector of the cable or, what is worse, blowing the drill pipe towards the operators. The entry of waste through the same circulation holes can also affect the coupling of the connector.

EXTRACT OF THE INVENTION In one aspect of the invention, it is an instrument for use in the bottom of the bore, designed to be suspended in a well by a pipe, which includes a housing, a circulation piston, a bypass member and a pressure compensation system. The housing forms a flow chamber in open communication, by fluid, with the interior of the pipe, a port of passage to allow the fluid to circulate between the flow chamber and the well, a mud chamber in communication -open with the well, and a hermetic chamber, separated from the flow chamber by a hermetic separation surface. The circulation piston separates the flow chambers and the flow chambers and is arranged to move between a first blocking position of the passage ports and a second exposure position of the passage ports., responding to the pressure in the flow chamber. The bypass member biases the circulation piston to its first position, and the pressure compensation system limits the pressure difference between the flow and hermetic chambers, thus limiting the pressure difference across the sealing surface. In some physical representations of the invention, the pressure compensation system has a floating piston, located between the flow chamber and the hermetic chamber, to transfer the pressure between the flow chamber and the sealed chamber. In some cases, the instrument also has an electrical conductor in the hermetic chamber, and an insulating fluid that fills the hermetic chamber around the electrical conductor. The insulating fluid consists, in some cases, of silicone or other electrical insulating hydraulic oil. In a physical representation of the invention of particular interest, the separation surface includes an electrical contact that communicates electrically with the electric conductor. In this physical representation, the pressure compensation system limits the pressure difference through the contact. In some arrangements, the separation surface includes a series of electrical contacts.

In some physical representations of the invention, the mud chamber is located between the flow chamber and the hermetic chamber. This instrument also includes a pressure tube in the flow chamber that extends through the mud chamber to transfer pressure from the inside - from the tube to the floating piston, in addition to a conductive tube that extends through the floating piston and the mud chamber to direct the driver through the mud chamber, under the pressure of the hermetic chamber, towards the contact. In some cases, the conductive tube extends along the inside of the pressure tube of the flow chamber. In some applications, the bypass member includes a compression spring. The pressure compensation system, in some physical embodiments of the invention, also has a check valve that limits the pressure in the sealed chamber that exceeds the pressure in the flow chamber. In some cases, the check valve limits the pressure difference, between the flow chamber and the hermetic chamber, to-less than about 100 pounds per square inch. Some physical representations of the instrument -includes, in addition, a sensor to measure a well characteristic. According to another aspect of the invention, improvements are provided for an instrument to be used in the bottom of the drill designed to be suspended in a well by means of a pipe. The instrument for the bottom of the perforation includes a housing that forms a flow chamber in open communication, by fluid, with the interior of the tube, a port of passage to allow the fluid to circulate between the flow chamber and the well , and a conductive chamber filled with an electrical insulating fluid. The instrument also has a hermetic electrical contact exposed to the flow chamber, and an electrical conductor that extends, through the conductive chamber, to the electrical contact. In this regard, the improvement includes the fact that the housing also forms a mud chamber and that the instrument also includes the following: a. a circulation piston separating the flow and mud chambers and arranged to move between a first blocking position of the passage ports and a second exposure position of the passage ports, in response to pressure in the first camera; b. a bypass member for biasing the circulation piston to its first position; and c. a pressure compensation system for limiting the pressure difference between the flow and conductive chambers in order to thereby limit the pressure difference through the hermetic electrical contact. The functions mentioned above are organized, in various aspects of the invention, in different combinations. In another aspect of the invention, a method for performing a function at the bottom of a well is provided. The method includes the following steps: 1. provide the instrument for the bottom of the hole described above; 2. lowering the instrument to the bottom of the well by means of a pipe; and 3. perform the function at the bottom of the hole. In some physical representations of the invention the method also includes, after the step of lowering the instrument into the well, pumping a connecting instrument along the pipe in a cable to mechanically attach the instrument to the bottom of the borehole. , in order to provide an electrical connection between the bottom pipe of the borehole and the surface of the well. The connection instrument is pumped along the pipe in a flow of fluid that circulates through the pass-through port of the instrument at the bottom of the borehole when the circulation piston is moved to its second position, exposing the ports of passage, by means of the pressure of the pipe. In some arrangements, the function to be performed on the bottom of the hole includes the measurement of a bottomhole characteristic. In some cases, the function to be carried out at the bottom of the hole includes moving the instrument to the bottom of the hole along the well and, while the instrument is displaced, recording a measurement of a bottomhole characteristic. The invention can improve the reliability of the connections at the bottom of the borehole, in humid environments, by resisting the ingress of debris and fluids from the wellbore into the drill pipe, thus improving the connector's capacity to establish a secure electrical connection and remain connected until you want to separate it. The invention can also improve, if properly applied and used, the safety of operation of the instrument in the well by reducing the risk that well fluids blow up the drill pipe.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1-5 illustrate in order the use of an electrical connector remotely coupled to a wellbore diaphragm probe. Figures 6A-6C illustrate the construction of the connector half used in the bottom of the borehole (CCFP) -from Figure 1.

Figure 6D is a cross-sectional view taken along line 6D-6D in Figure 6B. Figures 7A-7C illustrate the construction of the -middle corresponding to the connector cable (CCBD) of Figure 1. Figure 7D is a cross-sectional view taken along the line 7D-7D in Figure 7B. Figure 8 shows an alternative arrangement of the upper end of the CCBD. Figure 9 illustrates a function of the cleaning cup in a pipe. Figure 9A shows a cleaning cup located at the lower end of an instrument. Figure 10 is an enlarged and exploded view of the cleaning cup and related components. Figure 11 is an enlarged view of the set of female connectors of Figure 7B. Figure 12 is an exploded view, in perspective, of a subset of the set of female connectors of Figure 11. Figure 13 is an enlarged view of area 13 in Figure 11. Figure 14 is an enlarged view of the plural connector. ears of Figure 7B. Figure 15 is a view of the connector, as would be seen from position 15 in Figure 14.

DESCRIPTION OF THE PREFERRED PHYSICAL REPRESENTATIONS OF THE INVENTION Referring first to Figures 1 through 5, the connection system at the bottom of the bore is suitable for use with survey probes with sounding cable 0 either in an untubed well or in a cased hole 12, and is especially useful in situations where the well is deviated and / or the area to be recorded (ie zone 14) is at a considerable depth. In these figures, the well 12 has a horizontal section 16 that must be registered in the area 14, and is lined with a pipe 18 that extends from the surface of the well to the shoe of the casing 20. As shown in Figure 1, the logging probes 10 are provided with a wet connection head at the bottom of the bore (CCFP) 22 which is connected between an upper end of the logging probes and the drill pipe 24. As will be explained further on, the CCFP 22 provides a male section of an electrical connection - at the bottom of the borehole to establish an electrical communication between the logging probes 10 and a mobile logging unit 26. During the first step of the logging procedure , the probes 10 and the CCFP 22 are made to descend in the well 12 in connected sections of standard perforation pipe 24 until the probes 10 reach the upper end of the section of The well to be registered (that is, the upper part of zone 14). The drill pipe 24 is lowered using standard techniques and, while the drill pipe is not opened to allow fluid to enter from the well, at regular intervals - (ie, every 600 to 900 meters) the drill pipe it is filled with drilling fluid (ie, mud). As shown in Figure 2, when the probes 10 have reached the top of the zone 14, a wet connection head is pumped downwards (CC BD) 28 through the inner surface of the drill pipe in an electrical cable 30 that is unwound from the logging unit 26. The CCBD28 has a female connector which is coupled to the male connector of the CCFP. A secondary side cable entry (ELSC) 32, where pre-cable 30 has been introduced to provide a lateral outlet of the cable from the spliced drill pipe, -is coupled to the upper end of the drill pipe 24, and a cover for sludge (that is, from an upper drive of the sounding train or mud circulation system of the vast transmission run) is coupled to the ELSC32 for pumping - the mud, in a downward direction, through the inner surface of the drill pipe. For this purpose, normal mud pumping equipment is used (not shown). As will be described later, a specially constructed cleaning cup in the CCBD helps to develop a pre-sizing force in the CCBD28, due to the mud flow down the drill pipe, to push the CCBD to the bottom of the pipe. well and join it to CCFP 22 to form an electrical connection. A special valve (described later) in the CCFP 22 allows the flow of slurry to circulate from the perforation pipe to the inner surface of the well. As shown in Figure 3, the CCBD 28 is pumped downstream by the drill pipe 24 until it engages with the CCFP 22 to form an electrical connection between the survey probes 10 and the -diagraph unit 26. In At this point, the mud flow can be stopped and the mud cover 34 can be removed from the top of the drill pipe. The diagnostic probes 10 can be activated to verify the operation of the system or to perform a preliminary sounding while they are being lowered to the bottom of the well. As shown in Figure 4, the logging probes 10, CCFP 22, and CCBD 28 are either lowered or pushed to the bottom of the well by the normal methods with the drilling pipe, adding other pipe sections. 24 punching as they are needed. During this process, the ELSC 32 remains coupled to the drill pipe, providing a lateral outlet for the cable 30. Above the ELSC 32, the wire 30 rests on the outside of the drill pipe 24, avoiding having to skewer previously the cable 30 through any-section of the drill pipe with the exception of the ELSC 32, The descent process is coordinated between the operator of the logging unit and the operator of the drill pipe to simultaneously lower the pipeline perforation and the cable. At the bottom of the well, the sensing fingers or devices of the cushion 36 of the diag- nostic probe (if it has "them") are deployed, and the probes of the graph are removed making them go up the well to the top of the zone 14 while the readings of the sensors are recorded in the well's logging unit 26. As with the descent process, the rise of the diag- raphy probe is coordinated between the operator of the logging unit and the operator of the pipeline. of perforation in order to have the cable and drill pipe ascending simultaneously. Referring to Figure 5, after completing the log, the bottom power of the drill is deactivated and CCBD 28 is decoupled from CCFP 22 and extracted from the well. The ELSC 32 and the CCBD 28 are removed from the drill pipe and the rest of the pipe, including the CCFP and the logging probes are removed. Referring to Figures 6A to 6C, the CCFP 22 -contains two main sub-assemblies, the compendement cartridge sacidn from the wet connector at the bottom of the borehole (CCCP) 38 and the retention assembly from the wet connector at the bottom of the borehole (CRCP). 40. The lower end 41 of the CC CP 38 is connected to the diagnostic probes 10 (see Figure 1). The CRCP 40 is the upper end of the CCFP 22, and has an external housing 42 which is connected, at its lower end, to the CCFP 38 in a threaded joint 44 (Figure 6B). Attached to the inner surface of the housing of the CRCP 42 - with threaded fasteners 46 is a latch assembly containing three cantilever retaining fingers 48 extending radially inwardly and toward the CCCP to - secure the CCBD 28. Two separate centralizers axially 50 are also secured around the interior of the -commodation of the CRCP 42 in order to guide the lower end -of the CCBD to couple it with the set of male connectors -52 of the CCCP. The CCCP 38 contains the e-hydraulic electrical components of the CCFP. It has an external housing 54 - coupled by a threaded joint 55 to a lower block 56 with internal threads 57 at its lower end to temporarily join the CCFP to the diaphragm probes. In the upper end of the housing 54 is a threaded joint 58 which connects the housing 54 to a coupler 60. Severed threaded sleeves 62 in the seals 44, 55 and 58 allow the CCFP housing components 54, 60, 42 and 56 to be coupled without rotating either end of the CCFP. Block 56 contains an electrical connector with hermetic frame 64 for making the electrical connection of the -CCFP with the diaphragm probes. One function of the CCCP 38 is to provide exposed electrical contacts (in the form of a set of male connectors 52) which are electrically coupled to the diagnostic probes by the connector 64. This electrical coupling takes place through a multi-wire cable 66 which it extends upwards through a cable chamber -hermetic 68, towards the individual contacts 102 of the connector assembly 52. The cable 66 extends upwards through an oil tube 71, through the center of the CCFP. Chamber 68 is sealed by individual contact O-rings 70 in connector assembly 52, O-rings 72 in oil tube 71, gaskets 74 and 76 in piston 77, and O-rings 78 in block 56, and it is filled with an electrical insulating fluid, such as silicone oil. The pressure in the chamber 68 is maintained approximately at the pressure inside the drilling pipe 24 (Figure 1), near the top of the CCFP 22, by the pressure compensation system described -more completely to continuation. A sludge piston assembly 80 (Figure 6B), consisting of a piston 82, a piston collar 84, a piston stop 86, joints 88 and sliding friction reducers 90, is deflected, upwardly, against the nut -limator of the piston 92, by a piston spring of the mud 94. With the mud piston assembly in the position shown, with the stop 86 against the nut 92, the piston 82 effectively blocks the fluid preventing it from moving between the circular surface of the well 96 Cel area between the perforation pipe and the inner surface of the well; see Figure 1) and the inside of the drill pipe (i.e., the interior area 98) through three side ports 100 distributed around the CCFP diameter. When it works, the mud piston assembly 80 remains in this position - locking the ports until there is sufficient pressure in the circular crown of the well 96 (acting against the upper end of the piston 82) to overcome the force of preload deflecting the spring 94 and moving the mud piston assembly downwards, compressing the spring 94 and exposing the ports 100. Once exposed, the ports 100 allow a normal frontal circulation of the sludge descending along the pipeline of drilling and exiting through the - 100 ports inside the well. Once the pumping pressure is stopped, the piston spring of the mud 94 forces the sludge piston assembly 80 back to its position of locking the ports. By blocking the ports 100 in the CRCP housing 42, in the absence of pumping pressure in the drill pipe, the sludge piston assembly 80 effectively prevents the entry of unwanted flow from the well into the interior of the pipeline. drilling. This is especially useful when trying to avoid an explosion of the well through the drill pipe, and - that the waste transported by the mud from the well interferes with the proper functioning of the coupling and electrical sections of the system. . It also helps to avoid the return of fluid, where a sudden inrush of well fluids and the resulting upflow mudflow in the drill pipe can cause the CCFP and the -CCBD to break up prematurely. The male connector assembly 52 is composed of a series of nine contact rings 102, each of which is sealed by two O-rings 70 and separated by insulators 104. The interior of this set of contact rings and insulators is at pressure of the chamber 68, while the exterior of this assembly is exposed to the pressure of the drill pipe (i.e., the pressure -of the inner area 98). In order to maintain the structural integrity of this set of connectors, in addition to the reliability of the seals 70, it is important that the pressure difference across the set of connectors (i.e., the difference between the pressure in the chamber 68 and the pressure in area 98) is maintained at a low level. A large pressure difference (ie, greater than 100 psi) can cause the seals 70 to fail or, in extreme cases, the connector set to collapse. Even a minimal leak of drilling mud conducting electricity through the seals 70 into the interior of the chamber 68, due in part to a large difference between the pressure of the drill pipe and the pressure in the chamber 68, can negatively affect the reliability of electrical systems. The pressure compensation system maintains the pressure difference across the male connector set within a reasonable level, and deflects the pressure difference so that the pressure in chamber 68 is slightly higher (more than 50 and 100 psi) that the pressure in -the area 98. This "overcompensation" of the pressure in the chamber 68 causes any tendency for leaks to result in a leakage of non-conducting silicone oil from chamber 68 to area 98, instead from a drilling mud stream conducting electricity to the chamber 68. A circular ring 106 around the oil tube 71, formed partly between the oil tube 71 and the mud shaft 108 concentrically surrounding the oil tube 71, transmits the pressure of the drilling mud from the area 98, through the holes 110, to act against the upper side of the piston 77. The pressure of the mud is transferred through the piston 77, sealed by the Gaskets 74 and 76, to the inside of the oil chamber 68. During the assembly of the CCCP, the chamber 68 is filled with an electrical insulating fluid, such as silicone oil, through an oil fill check valve of a direction 112 (Figure 6D), such as a check valve of Mark Lee CKFA1876015A . To properly fill the oil chamber, a vacuum cleaner is first applied to the chamber through a purge port 114. With the vacuum cleaner applied, the oil is reintroduced into the chamber 68 through the purge port 114. This is repeated several times until the camera has been completely filled. The vacuum cleaner is then removed, the port 114 is sealed with a plug 116, and more oil is pumped into the chamber 68 through a check valve 112, extending a compensating spring 118, until an opening is opened. pressure limiting check valve 119 on the piston 77, indicating that the pressure in the chamber 68 has reached a desired level above the pressure in the chamber 98 (which, during the filling process, is generally found at atmospheric pressure). When the valve 119 indicates that the desired pressure has been reached (preferably 50 to 100 psi, typically), the oil filling tube is removed from the one-way check valve -112, leaving the chamber 68 pressurized The fill ports of the mud chamber 120, in the coupling 60, allow the circular crown of the -106 cycle and the internal volume above the piston 77 to be pre-filled with a recommended lubricating fluid, such as motor oil. , before use in the field. The lubrication fluid typically remains in the CCFP (specifically in the annulus 106 and the volume above the piston 77) during use in the well and is not easily displaced by the drilling mud, thus simplifying the maintenance of the instruments. In addition to the lubrication fluid, the application of abundant friction reducing material, such as LUBRIPLATE TM, on all sliding contact surfaces is recommended. Referring to Figures 7A to 7C, the CCBD 28 -contains a set of female connectors 140 which is coupled to the set of male connectors 52 of the CCFP 22 at the bottom -of the perforation. While lowering the CCBD to the bottom of the well, before coupling the CCFP, a sleeve 142 composed of an electrical insulating material is deflected to the lower end of the CCBD. A four-ring gasket 144 forms a seal against the outer diameter of the sleeve 142 to maintain the well fluids outside the CCBD until the sleeve is displaced by the male connector of the CCFP. A projection with the conical bottom 146 helps to align the CCBD to couple it with the CCFP. When pushed into the CCFP by sufficient inertial loads or mud pressure, the lower end of the CCBD extends through the retention fingers 48 of the CCFP (Figure 6A) until the retention fingers snap back behind. of a frangible retention ring 148 in the CCBD. As soon as the retaining ring 148 is engaged by the retaining fingers of the CC FP, it will resist decoupling of the CCFP and CCBD, that is, due to the movement of the drill pipe, vibration or fluid return. The retaining ring 148 can be selected from a range of rings with different maximum shear strengths (ie, from 1600 to 4000 pounds, depending on anticipated field conditions) so that the CCBD can be released from the CCFP. , after collecting data, simply pulling up on the deployment cable until the retaining ring 148 opens and releases the CCBD. The CCBD has an outer housing 150 and a welded assembly for cable tie 152 connected by means of a coupler 154 and appropriately split threaded rings 156. Within the outer housing 150 is a subset of cable mandrels with an upper mandrel 158 and a lower mandrel 160. The grooves 162 in the upper mandrel and the holes 163 FIGURE 7D) through the outer housing form a circulation path open from the inside of the drill pipe to a mud chamber 164 within the sub-assembly of mandrels for cable. The signal cables 165 of the set of female connectors 140 are directed between the outer housing 150 and the cable mandrel, along axial grooves on the external surface of the lower mandrel 160, through holes 166 in the upper mandrel 158, through the cable cavity 168, and individually connected to the lower pins of the connector assembly 170. Like the CCFP, the CCBD has a pressure compensation system to equalize the pressure through the sleeve 142 while maintaining the electrical components surrounded by an electrical insulating fluid, such as silicone oil, until the sleeve is displaced. Inside the lower mandrel 160 there is an oil chamber 172, separated from the mud chamber 164 by a compensating piston 174 with a water seal 175. The piston-174 can move freely inside the lower mandrel 160, so that the pressure in the mud and oil chambers it is substantially the same. Upper and lower springs 176 and 178 which lie within the mud and oil chambers 164 and 172, respectively, and deflect the sleeve 142 downwards. The oil chamber 172 communicates, by fluid, with the cavity of the cable 168 and by the grooves of -directing cables in the lower mandrel 160 and cable holes 166 in the upper mandrel 158, sealed against the pressure of the drilling pipe using joints 180 around the upper mandrel. Therefore, with the sleeve positioned as shown, the fluid in the drill pipe acts against the upper end of the compensating puddle 174, which transfers the pressure to the oil chamber 172 and the upper end of the sleeve. 174, balancing the pressure forces of the fluid in the sleeve. The filling ports 182 and 184, at the upper and lower ends of the oil-filled section of the CCBD, respectively, make it possible to fill the oil chamber 172 and cable cavity 168 after assembly. A safety valve 186 in the compensation piston allows the oil chamber to be pressurized in the assembly to a maximum of 100 psi over the pressure in the mud chamber 164 (ie atmospheric pressure during assembly). The upper end of the CCBD provides a mechanical and electrical connection with the sounding cable 30 (Figure 2). The connector assembly 170 has nine electrically isolated pins, each with an insulated flexible connection cable 188 for making electrical connections-with individual wires of the cable 30. A connector fixer 189 is screwed to the exposed end of the coupling 154 to hold the connector in position ^ The specific construction of the connector assembly 170 is discussed in more detail below. To mount the upper end of the CCBD to the cable, the housing of the cable gland 152 is screwed-first onto the end of the cable, together with the split cable seal 190, sealing nut 192, and mandrels-of the upper cleaning cups. lower 194 and 196, respectively. A standard self-tensioning cable gland fastener 197 is placed around the end of the cable to secure the end of the cable to the housing of the cable clamp against an internal flange 198. The cable threads are connected to the flexible connection cables 188 of the cable assembly. connectors, the housing of the clamping bushing 152 is connected to the coupling 154 with a threaded ring -particle 156, and electrical insulating grease, such as silicon grease, is pumped through the lubrication holes in the housing of the cable clamp. The cleaning cup 202, described in more detail below, is installed between the mandrels of the upper and lower cleaning cups 194 and 196 to restrict flow, through the drill pipe around the CCBD, and to develop a pressure force capable of moving the CCPE along the drilling pipe and coupling the CCBD to the CCFP at the bottom - of the drilling. The mandrel of the upper cleaning cup 194 is threaded into the housing of the cable gland 152 to hold the cleaning cup 202 in position, and tighten the sealing nut. Referring to Figure 8, an alternative arrangement for the upper end of the CCBD consists of two cleaning cups 202a and 202b, separated by a distance L, to -restrict further the flow around the CCBD. This arrangement is useful when using light, low viscosity slurries to pump, for example. An extension of the housing of the cable gland 204 appropriately connects the mandrels to the two cleaning cups. You can also use more -from two cleaning cups. Referring to Figure 9, the cleaning cup 202 creates a flow restriction with the corresponding pressure drop at point A. Since the rising pressure (i.e., the pressure at point B) is greater than the pressure As the descending (ie, pressure at point C), a net force develops in the cleaning cup to push the cup and its instrument downward. As shown in Figure 9A, a cleaning cup, ie, the cleaning cup 202C) may alternatively be placed near the bottom of an instrument 206 to pull the instrument toward the bottom of a pipe or well. This arrangement can be particularly useful, for example, for centering the instrument in order to protect extended functions near its downward end or with large diameters of the pipe / instrument or small diameter ratios to the length of the instrument. The radial space? E-drying between the outer surface of the cleaning cup and the inner surface of the pipe is a function of several factors, including the viscosity of the fluid. We have observed that a radial space of approximately 0.127 cm per side (ie, a diametral space of 0.254 cm) is suitable for most well drilling muds. Referring to Figure 10, the cleaning cup 202 is injection molded using a resilient material such as VITON or other fluorocarbon elastomer, and has a slit 210 on one side to facilitate installation and removal without the need to disengage the instrument cable. The conical sections 214 and 216 of the cleaning cup fit into corresponding holes in the mandrels of the upper and lower cleaning cup 194 and -196, respectively, and have exterior surfaces inclined about 7 degrees with respect to the longitudinal axis of the cup. cleaning cup. The length of the conical sections helps retain the cleaning cup within the -holes in the housing. Also, six fingers 217 extend through the holes 218 in the cleaning cup, between the mandrels of the upper and lower cups, to retain the cleaning cup during use. Circular guides 219 stamped on a surface of the cleaning cup help to adjust the cup to different external diameters to adapt it to various sizes of pipe. Other resilient materials may be used for the cleaning cup, although, ideally, the material of the cleaning cup must be able to withstand the severe abrasion that may occur along the walls of the pipe and the large variety of chemicals that can be found in wells. Other non-resilient materials that may be useful are also soft metals, such as bronze or aluminum, or hard plastics, such as polytetrafluoroethylene (TEFLON ™) or acetal homopolymer resin (DELRIN ™). The non-resilient cleaning cups can be formed into two overlapping legs for installation on a preassembled instrument. Referring to Figure 11, the set of female connectors 140 of the CCBD has a series of hem-bra contacts 220 disposed about a common axis 222. The contacts have a linear spacing, d, which corresponds to -the separations of the contacts. male of the CCFP male connector assembly (Figure 6A) and a sliding seal -224. The contacts 220 and the friction sealing rings 224 are supported within a respective insulator 226.

The contact stack, rubbing and insulating sealing rings are fastened within an outer sleeve 228, between an end fastener 230 and an upper mandrel 232. Referring also to FIGS. 12 and 13, each contact 220 is fabricated from a single piece of electrically conductive material, such as beryllium copper, and has a portion composed of a sleeve 234 with eight -extensive fingers 236 (preferably six or more). The contact -220 is preferably gold plated. Each of the two 236 is shaped to bend radially inwardly, in other words, to have, from the portion of the sleeve 234 to the distal end 237, a main section 238 - which extends radially inwardly and a secondary section. 240 extending radially outwardly, forming a radially innermost section 242 with a contact length d of approximately 0.381 cm. In manufacturing the contact 220 from a single piece of material, fingers 236, in their relaxed state as shown, have no residual bending stresses that tend to reduce their resistance to fatigue. The inner diameter d. of the contact 220, as measured between the contact surfaces 242 of exposed fingers, is slightly smaller than the external diameter of the male electrical contacts 102 of the CCFP (Figure 6A), so that the fingers 236 are pushed outwards during coupling with the male connector and provide a contact pressure between the contact surfaces 242 and the male contacts 102. The circumferential width, w, of each finger is minimal at the contact surface 242. We have observed that at making the contact so that the length d of the fingers, and the radial thickness, t, of the fingers-is approximately 75 percent of the radial distance, r, between the inner surface of the portion of the sleeve -234 and the contact surfaces 242, results in a contact construction that supports repeated couplings. The friction seal rings 224 are preferably molded with a resilient fluorocarbon elastomer, such as VITON ™. The internal diameter d? of the friction sealing rings 224 is also slightly smaller than the external diameter of the male contacts, so that the sealing rings tend to rub the residues of the surface of the male contacts during coupling. Preferably, the internal diameters d, and d. The contacts and sealing rings are approximately the same. The friction sealing rings 224 are molded with an electrical insulating material to reduce the possibility of causing a short circuit between the contacts in the presence of conductive fluids of the -electricity. The contact 220 has a soldered terminal 224 insulated on one side of the portion of its sleeve 234 for electrically connecting a cable 246. As shown in Figure 12, as the contact 220 is inserted in the insulator 226, the wire 246 is directed through an orifice 248 in the insulator. Alignment pins 250 in -other holes 248 in the insulator fit into the outer grooves 252 of the rubbing sealing ring 224 to align-the rubbing sealing ring with the insulation. A notch -254 in friction sealing ring fits around the welded terminus 244. The insulators 226 and the friction sealing rings 224 are formed with sufficient holes 248 and grooves 252, respectively, to be able to direct all the wires 246 from each contact. 220 on the connector - shows the upper end of the assembly for coupling to the seal ring assembly 170 (Figure 7B). With the contact 220 inserted in the insulator 226, the distal ends 237 of the contact fingers rest within an axial groove 256 formed by an inter-lip 258 of the insulator. The lip 258 protects the distal ends of the fingers so that they do not snag on the surfaces of the male connector assembly when uncoupled-the CCFP of the CCFP. Referring to Figure 14, the set of connectors 170 of the CCBD has a molded connector frame 280 with an electrical insulating material, such as polyethylacetone, polyethyletherketone or polyaryletherketone. The frame 280 is designed to withstand a high static differential pressure of up to 15,000 psi, for example, through an O-ring in a groove of the water seal 281, and has holes with outlet 282 into which spikes are inserted. electrical conductors 284 attached to lead wires 286. (Lead wires 286 form flexible connection cables 188 of Figure 7B). The stainless steel pins 17-4, plated in gold 284, are inserted in position until their lower flanges 288 rest against the bottom of rebored holes 290 in the connector frame. To seal the separation surface between the connector frame and the lead wires, a cable seal 292 is molded in position, around the wires and the connector frame - after stripping the insulation on the individual lead wires to obtain better adhesion to the sealed material. The shutter 292 will also have to withstand high differential pressures of up to 15,000 psi as those supported by the -connector set. We have observed that some high temperature fluorocarbon elastomers, such as VITON TM and KALREZ TM give good results for sealing the strands 292. To form an arc-shaped barrier between the adjacent pegs 284, and between the pegs and the coupling 154 (Figure 7B), on the face 294 of the frame of the connector 280 , individual insulators 296 are molded in position around each of the pins 284 between their lower and upper flanges, 288 and 298, respectively. The insulators 296 extend outwardly, through the plane of the face 294 of the connector frame, about 0.3048 cm. and are preferably molded from a high temperature fluorocarbon elastomer such as VITON ™ or KALREZ ™.

The insulators 296 offer protection against the formation of electric arcs that may occur along the face -294 of the connector frame if, for example, wet air or liquid water infiltrates the cable cavity 168 of the -CCBD (FIG. 7B). In addition to protecting against the formation of unwanted electric arcs, the insulators 296 also serve to prevent moisture from the connection from penetrating between the pins 284 and lead wires 286 inside the connector frame during storage and transportation. Referring also to Figure 15, the frame -of the connector 280 has an external diameter D, of approximately 2.41 cm in order to fit within the small internal diameters of the instruments (up to a minimum of 1 inch, -for example ), typical fact in the instruments used in the bottom of the perforation. The installed connector has a circular array of nine pins 284, each with the corresponding insulation 286 and lead wire 286.

Claims (6)

1. An instrument to be used in the bottom of the perforation, designed to be suspended in a well by means of a pipe and consisting of the following: a housing that defines a flow chamber in open communication, by means of fluid, with the interior of the pipe, a pass-through port to allow the flow of fluid between the flow chamber and the well, a mud chamber in open communication with the well, and a hermetic chamber separated from the flow chamber by a separating surface hermetic a circulation foot separating the flow and mud chambers and arranged so that it can move between a first position of blocking the port of passage and a second position of exposure of the port of passage, responding to the pressure in the chamber flow; a bypass member for biasing the circulation piston towards its first position; and a pressure compensation system for limiting the pressure difference between the flow and hermetic chambers, thereby limiting the pressure difference across the sealing surface. The instrument of claim 1 wherein the pressure compensation system comprises a floating piston, disposed between the flow chamber and the hermetic chamber, for transferring pressure between the flow chamber and the hermetic chamber. 3. The instrument of claim 1, further comprising an electrical conductor in the sealed chamber, and an insulating fluid filling the air-tight seal chamber of the electrical conductor. The instrument of claim 3, wherein the separation surface comprises an electrical contact in electrical communication with the electrical conductor, and wherein the pressure compensation system limits the pressure difference across the contact. The instrument of claim 4, wherein the mud chamber is located between the flow chamber and the hermetic chamber, and where the instrument further comprises: a pressure tube of the flow chamber extending from through of the mud chamber to transfer pressure from the inside of the pipe to the floating piston; and, a conductive tube extending through the floating piston and the mud chamber to direct the conductor through the mud chamber, under the pressure of the sealed chamber, towards contact. 6. The instrument of claim 1, further comprising a sensor for measuring a well characteristic. A method for performing a function in the bottom of a well comprising the following steps: providing the instrument of claim 1 for use in the bottom of the hole; to lower the instrument into the well in a pipeline; and, perform the corresponding function at the bottom of the hole. The method of claim 7 further comprising, after the step of lowering the instrument - in the well, pumping a connecting instrument, through the pipe, into a cable to mechanically couple it to the instrument at the bottom of the perforation, so as to provide an electrical connection between the pipe at the bottom of the drill-hole and the surface of the well, with the connection instrument being pumped, through the pipe, in a flow of fluid that circulates through the port of passage of the instrument from the bottom of the perforation, when the circulation piston is displaced to its second position of exposure of the passage through the pressure of the pipe. The method of claim 8, wherein the function of the bottom of the borehole comprises the measurement of a bottomhole characteristic. The method of claim 8, wherein the step of performing the function of the bottom of the borehole comprises the following steps: moving the instrument to be used at the bottom of the borehole along the borehole; and, while moving the instrument, make a diary of a characteristic of the bottom of the well.