Memory spontaneous potential measuring instrument

Abstract

The present invention provides a storage-type spontaneous potential measuring instrument, which comprises: a mandrel, on the surface of which a fiberglass shell is wound; at least two electrode rings, which are arranged on the mandrel and used for measuring the spontaneous potential curve of the entire well section; an upper sub, which is connected to the upper end of the mandrel through an intermediate sub and used for threaded connection with other instruments or drill tools; a lower sub, which is connected to the lower end of the mandrel and used for threaded connection with other instruments or drill tools; an upper cap, which is threadedly connected to the upper sub and used for preventing the thread of the external thread at the top of the upper sub from being damaged; a lower cap, which is threadedly connected to the lower sub and used for preventing the thread of the internal thread at the top of the lower sub from being damaged. The present invention has at least two electrode rings. When running in the hole, the drill string shell is led into the storage-type spontaneous potential measuring instrument through a cable as a reference electrode; the present invention can sample and store the spontaneous potential measured by the electrode rings and the difference between the two at equal time intervals.

Description

Technical Field

[0001] The present invention relates to the technical field of oil well logging, and more particularly, to a memory-type spontaneous potential measuring instrument. Background Art

[0002] The spontaneous potential logging curve shows obvious anomalies at the downhole permeable layer. Therefore, spontaneous potential logging is one of the important methods for dividing and evaluating oil and gas reservoirs.

[0003] The spontaneous potential is a DC signal. In the prior art, in wireline logging, the downhole spontaneous potential measuring electrode M is led to the surface through a cable and compared with the surface reference electrode N to obtain the spontaneous potential. The measurement principle is shown in Figure 1 Since the surface reference electrode is approximately infinitely far from the downhole spontaneous potential electrode and the surface reference electrode is relatively stable, the noise can be filtered out through filtering to obtain a relatively accurate spontaneous potential curve.

[0004] In the prior art, in logging while drilling without a cable, since there is no cable, the signal of the downhole spontaneous potential measuring electrode cannot be led to the surface, and the spontaneous potential cannot be measured on the surface. Only the drill string can be used as the reference electrode, and the spontaneous potential is measured by the downhole spontaneous potential measuring electrode in the downhole tool. The measurement principle is shown in Figure 2 When the drill string is stationary in the well, the drill string is relatively stable as the reference electrode at this time, and a relatively accurate spontaneous potential can be measured; when the drill string is lifted, due to the movement of the drill string, the friction between the drill string and the wellbore wall and the flow of the wellbore drilling fluid will occur, making the reference electrode unstable, and the measured spontaneous potential error is large.

[0005] The prior art cannot solve the problem of spontaneous potential measurement in the case of logging while drilling without a cable. Therefore, the present invention provides a memory-type spontaneous potential measuring instrument. Summary of the Invention

[0006] To solve the above problems, the present invention provides a memory-type spontaneous potential measuring instrument, which comprises:

[0007] A mandrel, on the surface of which a fiberglass shell is wound;

[0008] At least two electrode rings, which are arranged on the mandrel and used to measure the spontaneous potential curve of the entire well section;

[0009] An upper joint, which is connected to the upper end of the mandrel through an intermediate joint and used for threaded connection with other instruments or drill strings;

[0010] A lower joint, which is connected to the lower end of the mandrel and used for threaded connection with other instruments or drill strings;

[0011] An upper protective cap, which is threadedly connected to the upper joint and is used to prevent the thread of the external thread at the top of the upper joint from being damaged;

[0012] A lower protective cap, which is threadedly connected to the lower joint and is used to prevent the thread of the internal thread at the top of the lower joint from being damaged.

[0013] According to an embodiment of the present invention, the instrument includes:

[0014] An internal circuit, which is installed in the large through hole of the mandrel and is used to process the electrode signals generated by the electrode ring.

[0015] According to an embodiment of the present invention, the instrument includes:

[0016] A lead screw, which is used to connect the electrode ring and the internal circuit. The lead screw is threadedly connected to the electrode ring and sealed with a double O-ring, and the lead screw is insulated from the mandrel through a bushing.

[0017] According to an embodiment of the present invention, the instrument includes:

[0018] An insulating sleeve, which is installed outside the mandrel, and the electrode ring is wound outside the insulating sleeve;

[0019] A first outer sealing ring, which is arranged outside the electrode ring, and the first outer sealing ring and the electrode ring are sealed with a double O-ring to withstand external pressure;

[0020] A second outer sealing ring, which is sealed with a double O-ring with the fiberglass outer shell to withstand external pressure;

[0021] A third insulating pad, which is used to isolate adjacent electrode rings.

[0022] According to an embodiment of the present invention, the upper joint and the mandrel are insulated, and the instrument includes:

[0023] A first insulating pad, which is used for electrical insulation between the intermediate joint and the electrode ring;

[0024] An anti-rotation inner insulating sleeve, which is connected to the first insulating pad and is used for electrical insulation between the intermediate joint and the mandrel;

[0025] A compression nut, which is threadedly connected to the mandrel and is used to lock the intermediate joint on the mandrel;

[0026] A second insulating pad, which is connected to the anti-rotation inner insulating sleeve and is used for insulation between the intermediate joint and the compression nut;

[0027] An inner insulating sleeve, which is fixed to the upper joint with screws and is used for insulation between the compression nut and the upper joint;

[0028] A shaft retaining ring is used to prevent the compression nut from loosening.

[0029] According to an embodiment of the present invention, the assembly sequence is as follows: the lower protective cap, the lower joint, the mandrel, the intermediate joint, the upper joint, the upper protective cap, which are compressed by the compression nut, and the shaft retaining ring prevents loosening.

[0030] According to an embodiment of the present invention, a double O-ring seal is adopted between the intermediate joint and the third outer seal ring outside the electrode ring.

[0031] According to an embodiment of the present invention, the upper joint and the intermediate joint are connected by threads and sealed with a double O-ring.

[0032] According to an embodiment of the present invention, the upper joint includes:

[0033] A through hole in the upper joint is used for the instrument signal to pass through the wire and the installation of electrical connectors, facilitating electrical connection with other instruments.

[0034] According to an embodiment of the present invention, the mandrel includes:

[0035] A small through hole in the mandrel is used for the instrument signal to pass through the wire and provides space for the installation of the measurement circuit.

[0036] The memory-type spontaneous potential measuring instrument provided by the present invention has at least two electrode rings. When lowering the well, the drill string housing is led into the memory-type spontaneous potential measuring instrument through a cable as a reference electrode; the present invention can sample and store the spontaneous potential measured by the electrode rings and the difference between the two at equal time intervals; the present invention can perform superposition processing on the spontaneous potential measured by the electrode rings and the difference between the two according to the depth change to obtain the spontaneous potential curve of the entire well section.

[0037] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, the claims, and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0039] Figure 1 Shows the schematic diagram of wireline logging in the prior art;

[0040] Figure 2 Shows the schematic diagram of logging while drilling without wireline in the prior art;

[0041] Figure 3 Shows a schematic structural diagram of a memory spontaneous potential measuring instrument according to an embodiment of the present invention;

[0042] Figure 4 Shows a schematic structural diagram of the insulating part between the upper joint and the mandrel according to an embodiment of the present invention;

[0043] Figure 5 Shows a schematic structural diagram of the insulating part between electrode rings according to an embodiment of the present invention;

[0044] Figure 6 Shows a schematic connection diagram of the electrode ring and the internal circuit according to an embodiment of the present invention; and

[0045] Figure 7 Shows a schematic diagram of the principle of measuring the spontaneous potential curve of the entire well section according to an embodiment of the present invention.

[0046] In the drawings, the same components are denoted by the same reference numerals. The drawings are not drawn to actual scale.

[0047] The meanings of the reference numerals in the drawings are as follows: 1, mandrel; 2, first electrode ring; 3, second electrode ring; 4, upper joint; 5, intermediate joint; 6, lower joint; 7, upper protective cap; 8, lower protective cap; 9, first outer sealing ring; 10, second outer sealing ring; 11, fiberglass outer shell; 12, large through-hole of the mandrel; 13, lead screw; 14, bushing; 15, first insulating sleeve; 16, second insulating sleeve; 17, third outer sealing ring; 18, third insulating pad; 19, first double O-ring seal; 20, second double O-ring seal; 21, fourth insulating pad; 22, lead sheath; 23, small through-hole of the mandrel; 24, first insulating pad; 25, inner anti-rotation insulating sleeve; 26, compression nut; 27, second insulating pad; 28, inner insulating sleeve; 29, screw; 30, shaft retaining ring; 31, through-hole of the upper joint. Detailed Description of the Invention

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer, the following further details the embodiments of the present invention with reference to the accompanying drawings.

[0049] In the prior art, the main reason for the poor measurement of spontaneous potential in the case of non-cable drill string conveyance is that without a cable, the ground reference potential cannot be used, and only the drill string can be used as the reference electrode. However, when the drill string is lifted for logging, the reference electrode is interfered with, resulting in poor measurement of spontaneous potential. To address this problem, a memory spontaneous potential measuring instrument for non-cable drill string conveyance is designed, and its overall structure is as Figure 3 shown.

[0050] Figure 3Shows a schematic structural diagram of a memory spontaneous potential measuring instrument according to an embodiment of the present invention.

[0051] As Figure 3 shown, the memory spontaneous potential measuring instrument includes a mandrel 1, at least two electrode rings (for example, including a first electrode ring 2 and a second electrode ring 3), an upper sub 4, an intermediate sub 5, a lower sub 6, an upper cap 7, a lower cap 8, a first outer sealing ring 9, a second outer sealing ring 10, and a fiberglass outer shell 11.

[0052] Specifically, the surface of the mandrel 1 is wound with the fiberglass outer shell 11. The present invention adopts an integral mandrel design with high tensile and compressive strengths. The mandrel material is 05Cr17Ni4Cu4Nb, the surface is wound with high-strength fiberglass, and it is bonded and cured with a high-temperature curing resin, having high wear resistance.

[0053] The electrode rings are arranged on the mandrel 1 and are used to measure the spontaneous potential curve of the entire well section. The outer surface of the electrode ring is wound with lead sheets 22 of a certain width (2 mm) to ensure good conduction between the electrode ring and the formation, ensure good electrical conductivity of the electrode ring, and improve the quality of spontaneous potential logging data.

[0054] In one embodiment, the memory spontaneous potential measuring instrument needs to be provided with at least two electrode rings. Figure 3 Shows a schematic structural diagram of a memory spontaneous potential measuring instrument including two electrode rings. As Figure 3 shown, the electrode rings include a first electrode ring 2 and a third electrode ring 3.

[0055] In practical applications, the drill string housing is led into the memory spontaneous potential measuring instrument through a cable as a reference electrode, and the lower end of the drill string is electrically isolated through an insulating hard electrode. The memory spontaneous potential measuring instrument is preferably placed in the lower half of the instrument string to keep a sufficient distance between the memory spontaneous potential measuring instrument and the drill string.

[0056] Figure 6 Shows a schematic connection diagram of the electrode ring and the internal circuit according to an embodiment of the present invention.

[0057] As Figure 6 shown, the distance between the first electrode ring 2 (SP1 electrode) and the second electrode ring 3 (SP2 electrode) is ΔL. The first electrode ring 2 and the second electrode ring 3 respectively measure the first electrode signal and the second electrode signal. The internal circuit processes the first electrode signal and the second electrode signal, combines the reference potential to obtain the spontaneous potentials SP1 and SP2, and then measures the differential spontaneous potential SP3 between the two electrodes through the spontaneous potentials SP1 and SP2.

[0058] During logging, when the drill string is stationary, the measured spontaneous potentials SP1 and SP2 are the actual spontaneous potentials of the formation at the corresponding depths, and SP3 is the potential difference between the first electrode ring 2 and the second electrode ring 3 (spontaneous potential SP2 - spontaneous potential SP1).

[0059] When the drill string is moving, due to noise interference, the measured spontaneous potentials SP1 and SP2 are the spontaneous potentials mixed with noise. However, since SP3 is measured differentially through the first electrode ring 2 and the second electrode ring 3, it is still the actual potential difference between the first electrode ring 2 and the second electrode ring 3 and is not affected by noise.

[0060] During storage logging, the depth of the surface isochronous sampling instrument and the spontaneous potentials SP1, SP2, and SP3 of the downhole instrument are sampled isochronously. After the well logging is completed and the downhole instrument returns to the surface, the spontaneous potentials SP1, SP2, and SP3 are corresponded to the instrument depth one by one according to time. Take the spontaneous potentials SP1 and SP2 measured when the drill string is stationary (i.e., the depth data remains unchanged) as the spontaneous potential reference SP. When the instrument moves to the next depth point, add the SP3 at this depth point to SP as the SP at this depth, and perform superposition processing in turn to obtain the spontaneous potential curve of the entire well section.

[0061] Figure 7 Shows the schematic diagram of the measurement principle of the spontaneous potential curve of the entire well section according to an embodiment of the present invention.

[0062] When the memory spontaneous potential measuring instrument is at depth h0, the memory spontaneous potential measuring instrument is in a stationary state at this time. Due to no external interference, the measured spontaneous potentials SP1 and SP2 are the spontaneous potential values of the formation at the corresponding depths. Thus, the spontaneous potential value of the formation at depth h0 is:

[0063] SP 0 = SP1 0

[0064] SP3 0 = SP2 0 - SP1 0

[0065] When logging while pulling up or lowering the drill string, when the instrument moves to depth h1, due to the unstable potential of the measurement reference electrode caused by the movement of the drill string, SP1 1 , SP2 1 The measured spontaneous potential cannot truly reflect the spontaneous potential at the corresponding depth. However, the differential SP3 between the SP1 electrode and the SP2 electrode measured at this time 1 Is not affected by interference and can truly reflect the potential difference between the two electrodes. Thus, the spontaneous potential value of the formation at depth h1 is:

[0066] SP 1 = SP0 +SP3 0

[0067] SP3 1 = SP2 1 -SP1 1

[0068] And so on, the depths h2 to h can be obtained. i (where i > 2), the spontaneous potential value of the formation is:

[0069] SP 2 = SP 1 +SP3 1

[0070] SP3 2 = SP2 2 -SP1 2

[0071] SP 3 = SP 2 +SP3 2

[0072] ……

[0073] SP3 i-1 = SP2 i-1 -SP1 i-1

[0074] SP i = SP i-1 +SP3 i-1

[0075] Generally, the depth sampling rate of the spontaneous potential is 10 points per meter, that is, the depth sampling interval is 0.1 meter. The distance between the SP1 electrode and the SP2 electrode is designed to be 0.1 meter to solve the depth alignment problem in depth migration processing.

[0076] During the process of raising or lowering the drill string, after moving a certain distance (generally about the length of each stand of drill pipe), 1 stand of drill pipe needs to be removed or connected. When removing or connecting the drill pipe, only the drill pipe above the drilling platform is in a moving state, and the drill pipe in the well is stuck on the drilling platform and in a static state. At this time, for SP i perform calibration.

[0077] Step 1: SP i = SP1 i

[0078] When the drill pipe removal or connection is completed and the drill pipe resumes raising or lowering:

[0079] Step 2: SP i+1 = SP i +SP3 i

[0080] When the drill string is removed or connected again, the SP at the current depth is corrected again, and steps 1 and 2 are repeated until the measurement is completed.

[0081] Generally, when the drill string moves about 30 meters, the drill string needs to be removed or connected. During the measurement process, the drill string needs to be removed or connected multiple times (for example, for a well depth of 3000 meters, the number of times the drill string in the well is stationary is about 100 times). The SP measurement value can be corrected multiple times, so that the measurement is more accurate and a good spontaneous potential curve for the entire well section can be obtained.

[0082] The present invention makes full use of the spontaneous potential measured in the stationary state of the instrument when replacing the drill string during logging with the drill string as the reference, measures the formation spontaneous potential through dynamic differential spontaneous potential processing, and can correct the spontaneous potential measurement value multiple times.

[0083] In one embodiment, the upper sub 4 is connected to the upper end of the mandrel 1 through an intermediate sub 5 and is used for threaded connection with other instruments or drill strings. The lower sub 6 is connected to the lower end of the mandrel 1 (for example, by threaded connection) and is used for threaded connection with other instruments or drill strings. The upper cap 7 is threadedly connected to the upper sub 4 and is used to prevent damage to the thread of the external thread at the top of the upper sub 4. The lower cap 8 is threadedly connected to the lower sub 6 and is used to prevent damage to the thread of the internal thread at the top of the lower sub 6.

[0084] Furthermore, the upper and lower subs are used for threaded connection with other instruments or drill strings when the instrument is lowered into the well. During transportation and storage, the upper cap 7 is threadedly connected to the top thread of the upper sub 4, and the lower cap 8 is threadedly connected to the lower sub 6, which is used to protect the stored spontaneous potential measuring instrument, prevent damage to the threads of the external thread at the top of the upper sub 4 and the internal thread at the top of the lower sub 6 of the instrument, and is also convenient for handling, and it is removed when connecting the instrument or drill string.

[0085] In one embodiment, the first outer sealing ring 9 is used for insulation between the first electrode ring 2 and the second electrode ring 3, and the second outer sealing ring 10 is used for insulation between the first electrode ring 2 and the fiberglass shell 11.

[0086] In summary, as Figure 3 shown, the stored spontaneous potential measuring instrument is beneficial to the insulation between electrode rings, the sealing, pressure resistance and tensile resistance performance of the instrument, and is convenient for wire connection in terms of structural design.

[0087] Figure 4 shows a schematic structural diagram of the insulation part between the upper sub and the mandrel according to an embodiment of the present invention.

[0088] In one embodiment, the memory spontaneous potential measuring instrument further includes an internal circuit, which is installed in the large through hole 12 of the mandrel and is used to process the electrode signals generated by the electrode rings. Further, the internal circuit can filter and amplify the electrode signals generated by the first electrode ring 2 and the second electrode ring 3 respectively, and perform differential SP3 amplification on the two signals, and then perform A / D conversion on the spontaneous potentials SP1, SP2, and SP3 at different depths and store them at certain time intervals.

[0089] In one embodiment, the lead screw 13 is used to connect the electrode ring and the internal circuit. The lead screw 13 is threadedly connected to the electrode ring and sealed by the first double O-ring seal 19. The lead screw 13 is insulated from the mandrel 1 through the bushing 14. In addition to connecting the electrode ring and the internal circuit, the lead screw 13 also functions to prevent the electrode ring from rotating and as a lead wire.

[0090] It should be noted that the number of lead screws 13 depends on the number of electrode rings. Each electrode ring has a lead screw 13 for connecting itself to the internal circuit, and the present invention does not limit the number of lead screws 13.

[0091] In one embodiment, the insulating sleeve is installed outside the mandrel 1, and the electrode rings are wound outside the insulating sleeve. Specifically, Figure 4 the illustrated embodiment includes two insulating sleeves, namely the first insulating sleeve 15 and the second insulating sleeve 16. The first insulating sleeve 15 and the second insulating sleeve 16 are made of high-temperature fiberglass material, which is used to isolate the mandrel 1 from the electrode rings and at the same time play a role of insulation and centering. The first insulating sleeve 15 is used to isolate the mandrel 1 from the first electrode ring 2, and the second insulating sleeve 16 is used to isolate the mandrel 1 from the second electrode ring 3.

[0092] In one embodiment, the first outer seal ring 9 is arranged outside the electrode ring, and the double O-ring seal is used between the first outer seal ring 9 and the electrode ring to withstand the external pressure. The double O-ring seal is used between the second outer seal ring 10 and the fiberglass housing 11 to withstand the external pressure. The second double O-ring seal 20 is used between the second outer seal ring 10 and the first electrode ring 2 to withstand the external pressure. Further, the first outer seal ring 9 and the second outer seal ring 10 are made of polyether ether ketone rings.

[0093] In one embodiment, the third insulating pad 18 is used to isolate adjacent electrode rings. As Figure 4 shown, the third insulating pad 18 is used to isolate the first electrode ring 2 and the second electrode ring 3. The fourth insulating pad 21 is used to isolate the mandrel 1 from the first electrode ring 2.

[0094] Figure 5 shows a schematic diagram of the insulation part structure between electrode rings according to an embodiment of the present invention. As Figure 5As shown, the upper joint 4 and the mandrel 1 are insulated. The memory spontaneous potential measuring instrument includes: the first insulating pad 24, the anti-rotation insulating sleeve 25, the compression nut 26, the second insulating pad 27, the inner insulating sleeve 28, the screw 29, and the shaft retaining ring 30.

[0095] In one embodiment, the first insulating pad 24 is used for electrically insulating the intermediate joint 5 and the electrode ring. Specifically, the first insulating pad 24 is used for electrically insulating the intermediate joint 5 and the second electrode ring 3. Further, the first insulating pad 24 is made of laminated fiberglass board and can withstand a pressure of 30 t when compressed.

[0096] In one embodiment, the anti-rotation insulating sleeve 25 is connected to the first insulating pad 24 and is used for electrically insulating the intermediate joint 5 and the mandrel 1. Further, the anti-rotation insulating sleeve 25 insulates and isolates the mandrel 1 and the intermediate joint 5 and can withstand an anti-rotation torque of 800 N·m.

[0097] In one embodiment, the compression nut 26 is threadedly connected to the mandrel 1 and is used for locking the intermediate joint 5 onto the mandrel 1.

[0098] In one embodiment, the second insulating pad 27 is connected to the anti-rotation insulating sleeve 25 and is used for insulating the intermediate joint 5 and the compression nut 26. The second insulating pad 27 is installed outside the mandrel 1, the second electrode ring 3 is wound outside the second insulating pad 27, and the third outer sealing ring 17 is used to withstand the external pressure outside the second electrode ring 3.

[0099] Further, the second insulating pad 27 is made of laminated fiberglass board and can withstand a tensile force of 30 t when pulled, and at the same time has a secondary pressure-bearing and anti-irrigation function. The two ends of the third outer sealing ring 17 are sealed with O-rings and internally supported to withstand an external pressure of 206 MPa. A double O-ring seal is used between the intermediate joint 5 and the third outer sealing ring 17.

[0100] In one embodiment, the inner insulating sleeve 28 is fixed to the upper joint 4 by the screw 29 and is used for insulating the compression nut 26 and the upper joint 4. The inner insulating sleeve 28 functions as insulation protection, fills the gap between the intermediate joint 5 and the compression nut 26, and prevents moisture or impurities from conducting between the two. Further, the inner insulating sleeve 28 is fixed to the upper joint 4 by the screw 29, and the upper joint 4 and the intermediate joint 5 are threadedly connected and double O-sealed.

[0101] In one embodiment, the shaft retaining ring 30 is used to prevent the compression nut 26 from loosening. The through hole 31 in the upper joint is used for the instrument signal to pass through and the installation of the electrical connector, facilitating electrical connection with other instruments. The small through hole 23 in the mandrel is used for the instrument signal to pass through and provides space for the installation of the measurement circuit.

[0102] In one embodiment, each component is arranged in the order of Figure 3 、Figure 4 and Figure 5 They are assembled from the right end in the order shown, that is, the assembly order is: lower protective cap 8, lower joint 6, mandrel 1, intermediate joint 5, upper joint 4, upper protective cap 7, and are tightened by compression nut 26, and lock washer 30 is used to prevent loosening.

[0103] In summary, the memory-type spontaneous potential measuring instrument provided by the present invention has at least two electrode rings. When running in the hole, the drill pipe housing is led into the memory-type spontaneous potential measuring instrument through a cable as a reference electrode; the present invention can sample and store the spontaneous potential measured by the electrode rings and the difference between the two at equal time intervals; the present invention can superimpose and process the spontaneous potential measured by the electrode rings and the difference between the two according to the depth change to obtain the spontaneous potential curve of the entire well section.

[0104] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and do not imply limitation.

[0105] The phrase "an embodiment" or "embodiments" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment" or "embodiments" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0106] Although the embodiments disclosed in the present invention are as above, the content described is only an embodiment for facilitating the understanding of the present invention and is not intended to limit the present invention. Any person skilled in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed by the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A memory-type spontaneous potential measuring instrument, characterized in that, The instrument includes: A mandrel with a fiberglass shell wound around its surface; At least two electrode rings arranged on the mandrel for measuring the spontaneous potential curve of the entire well section; An upper sub, which is connected to the upper end of the mandrel through an intermediate sub and is used for threaded connection with other instruments or drill tools; A lower sub, which is connected to the lower end of the mandrel and is used for threaded connection with other instruments or drill tools; An upper protective cap, which is threadedly connected to the upper sub and is used to prevent damage to the threads of the external threads at the top of the upper sub; A lower protective cap, which is threadedly connected to the lower sub and is used to prevent damage to the threads of the internal threads at the top of the lower sub; An internal circuit installed in the large through-hole of the mandrel for processing the electrode signals generated by the electrode rings; A lead screw used to connect the electrode ring and the internal circuit. The lead screw is threadedly connected to the electrode ring and sealed with double O-rings. The lead screw is insulated from the mandrel through a bushing; An insulating sleeve installed outside the mandrel, with electrode rings wound around the outside of the insulating sleeve; A first outer sealing ring arranged outside the electrode ring. The first outer sealing ring and the electrode ring are sealed with double O-rings to withstand external pressure; A second outer sealing ring, which is sealed with double O-rings between it and the fiberglass shell to withstand external pressure; A third insulating pad used to isolate adjacent electrode rings.

2. The memory-type spontaneous potential measuring instrument according to claim 1, wherein, The upper sub and the mandrel are insulated. The instrument includes: A first insulating pad used for electrical insulation between the intermediate sub and the electrode ring; An anti-rotation inner insulating sleeve connected to the first insulating pad and used for electrical insulation between the intermediate sub and the mandrel; A compression nut threadedly connected to the mandrel and used to lock the intermediate sub on the mandrel; A second insulating pad connected to the anti-rotation inner insulating sleeve and used for insulating the intermediate sub and the compression nut; An inner insulating sleeve fixed to the upper sub with screws and used for insulating the compression nut and the upper sub; A shaft retaining ring used to prevent the compression nut from loosening.

3. The memory-type spontaneous potential measuring instrument according to claim 2, wherein, The assembly sequence is as follows: lower protective cap, lower sub, mandrel, intermediate sub, upper sub, upper protective cap, which are tightened by the compression nut, and the shaft retaining ring prevents loosening.

4. The memory-type spontaneous potential measuring instrument according to claim 1, characterized in that, The intermediate sub and the third outer sealing ring outside the electrode ring are sealed with double O-rings.

5. The memory type spontaneous potential measuring instrument according to claim 1, wherein, The upper sub and the intermediate sub are threadedly connected and sealed with double O-rings.

6. The memory-type spontaneous potential measuring instrument according to claim 1, characterized in that, The upper sub includes: An upper sub through-hole used for instrument signal wire passing and installation of electrical connectors, facilitating electrical connection with other instruments.

7. The memory type spontaneous potential measuring instrument according to claim 1, wherein The mandrel includes: A mandrel small through-hole used for instrument signal wire passing and providing space for the installation of the measurement circuit.

Images