CN-118884548-B - Preparation method of nonradioactive tracing ceramsite with stable signal-to-noise ratio

CN118884548BCN 118884548 BCN118884548 BCN 118884548BCN-118884548-B

Abstract

The invention discloses a preparation method of nonradioactive tracing ceramic particles with stable signal-to-noise ratio, which designs a method for acquiring capture gamma value zeta o of a unit volume of a tracing ceramic particle biscuit, establishes a method for regulating and controlling the content of trace elements contained in the tracing ceramic particles on line in real time based on zeta o value, eliminates the phenomenon of low and high content of trace elements caused by uneven mixing or other factors in the production process of the tracing ceramic particles, and accurately controls the content of trace elements within a set threshold value. According to feedback of underground measured data zeta Measuring , a set threshold zeta Threshold value of the tracing ceramsite is adjusted in real time, underground linkage is achieved on the well, stable signal to noise ratio can be achieved when the fracturing crack information is monitored by using a neutron activation prompt gamma ray method of the tracing ceramsite under a complex fracturing environment, sudden high and sudden low of capture gamma signals can be avoided when different logging instrument parameters, well bore environments and oil and gas reservoirs are used for logging the fracturing cracks, and accordingly logging success rate is improved.

Inventors

LI XIANGHUI
DONG MINGJING
LI CANRAN
CHEN HAIJUN
MENG CHUANG
YUAN SUHUA
WANG XIAOHUI
LI ZHENHUA
LI TIANTIAN
WANG HAOLONG

Assignees

河南省科学院同位素研究所有限责任公司
河南省同新科技有限责任公司
河南省科学院

Dates

Publication Date: 20260508
Application Date: 20240708

Claims (8)

1. The preparation method of the non-radioactive tracing ceramsite with stable signal-to-noise ratio is characterized by comprising the following steps of: the method comprises the steps of (1) adding raw ore weighed according to weight into a ball mill after coarse crushing, grinding into mixed powder, and transferring the powder to a bin (1) after grinding to target fineness, wherein the powder in the bin (1) is weighed onto a belt scale (3) through a first discharge valve (2), and the weighed mixed powder is transferred into a granulator (5) through a second discharge valve (4); The zeta Threshold value is a set threshold range of capture gamma value per unit volume, the control system (12) calculates the dosage of water and tracer liquid required by the preparation of the tracer haydite according to the threshold, and the water in the water tank (17) and the tracer liquid in the tracer liquid tank (16) enter the mixing homogenizer (14) through the third flow valve (18) and the second flow valve (15) respectively to form uniformly mixed tracer solution; Step (3), the tracer liquid in the mixing homogenizer (14) is atomized and sprayed into the granulator (5) through a first flow valve (13) to prepare a tracer haydite biscuit (30), and then the tracer haydite biscuit is transferred to a first conveyor belt (7) through a third discharge valve (6), dried and sieved, and finally the tracer haydite biscuit meeting the particle size requirement is sieved; The method comprises the steps of (4) transmitting a trace ceramsite biscuit to a detection unit (9), wherein the detection unit (9) comprises a moderating body thickness measuring device, a trace ceramsite biscuit neutron activation effective radius R measuring device and a unit volume capture gamma value obtaining device, wherein fast neutrons emitted by a neutron source (19) of a first logger are converted into thermal neutrons or epithermal neutrons through a moderating body (23), and a thermal neutron detector (24) is used for monitoring the change of the thermal neutron counting rate and determining the optimized value of the moderating body thickness according to the change; The method comprises the steps of (5) adding a trace ceramsite biscuit (30) into a trace ceramsite biscuit neutron activation effective radius R measuring method device through a third conveyor belt (31), wherein when a fourth discharge valve (28) discharges, the thickness of a slowing body (23) coated with the trace ceramsite biscuit in the trace ceramsite biscuit neutron activation effective radius R measuring method device is gradually thinned; The method comprises the steps of (6) measuring the distance h i between a charge level indicator (32) and the upper surface of a trace ceramsite biscuit covered on a slowing body, wherein fast neutrons emitted by a neutron source (19) are slowed down to form thermal neutrons or epithermal neutrons, and the thermal neutrons are captured by high neutron capture section elements contained in the trace ceramsite to generate instant gamma rays; The method comprises the steps of (7) enabling a tracing ceramsite biscuit (30) to enter a unit volume capture gamma value obtaining method device through a fifth conveying belt (36), enabling a rotating device (33) to control a logging instrument to rotate, enabling a neutron source (19) to horizontally emit neutrons to perform neutron horizontal irradiation on the tracing ceramsite biscuit around the inside of an analog shaft, enabling the effective radius of action to be R, enabling a lifting device (38) to control the logging instrument to lift, obtaining neutron activation reaction height h, and further calculating effective neutron activation volume V, and obtaining unit volume capture gamma value zeta o ; If the capture gamma value zeta o in unit volume exceeds the set threshold zeta Threshold value , the content of trace elements contained in the trace ceramsite product is considered to be not up to standard, the control system (12) automatically calculates the deviation value of the concentration of the trace solution in the mixing homogenizer (14) and gives out an instruction, the proportion of water and the trace solution entering the mixing homogenizer (14) is regulated by controlling the third flow valve (18) and the second flow valve (15), and the aim of regulating and controlling the concentration of the trace solution in the mixing homogenizer (14) in real time is fulfilled, so that the real-time online accurate control of the content of the trace elements in the trace ceramsite biscuit is realized; If the capture gamma value zeta o of unit volume is within the set threshold zeta Threshold value , the content of the trace element contained in the trace ceramsite product is considered to reach the standard, at the moment, the trace ceramsite blank is conveyed into a tunnel kiln to be calcined at high temperature, and finally the trace ceramsite for monitoring the fracturing cracks is prepared, wherein the capture gamma value zeta Ceramic ware of unit volume is the capture gamma value zeta; The method comprises the steps of (10) obtaining a downhole actual measurement value zeta Measuring by a logging instrument by means of a gamma detector, wherein zeta Ceramic ware value is used for guiding design and construction of a downhole fracturing scheme, and trace ceramsite with zeta Ceramic ware value is used for actual logging of a fracturing fracture; And (11) establishing databases of zeta Measuring under different well conditions, and adjusting and optimizing a set threshold zeta Threshold value in the process of preparing the tracing ceramic particles in real time by using the values of zeta Threshold value , so as to continuously and iteratively optimize, finally realizing the accurate control of the content of the trace elements in the high neutron capture section of the tracing ceramic particles, and realizing that a gamma detector can always obtain stable signal to noise ratio in a complex underground fracturing environment, thereby achieving the purpose of finely describing underground fracturing cracks during hydraulic fracturing exploitation.
2. The method according to claim 1, wherein the tracer liquid in the step (2) is one or any combination of ion solutions containing gadolinium, boron and samarium high neutron capture cross-section elements.
3. The method according to claim 1, wherein the optimized value of the thickness of the moderating body in the step (4) is that the thickness of the moderating body is increased, the thermal neutron count is increased continuously, and when the fast neutrons are almost completely converted into the thermal neutrons, the reading of the thermal neutron detector (24) tends to be stable and unchanged, and the thickness of the corresponding moderating body is the optimized value of the designed thickness of the moderating body in the detecting unit.
4. The preparation method of the gamma-ray tracing device according to claim 1, wherein the discrimination principle of the neutron activation effective radius R in the step (6) is that when the fourth discharge valve (28) starts to discharge, the thickness of the upper-layer tracing ceramsite biscuit is larger, the upper-layer tracing ceramsite biscuit cannot be activated by neutrons due to a longer distance, the neutron activation effective radius R is smaller than the thickness of the upper-layer ceramsite biscuit, a neutron activation area is always stabilized within a limited neutron activation effective radius R, gamma values obtained by the near-well gamma detector (20) and the far-well gamma detector (21) are the highest and stable, the whole tracing ceramsite biscuit in the device is activated by neutrons with the further discharge of the fourth discharge valve (28), the total number of the activation is continuously reduced, the neutron activation effective radius R is larger than the thickness of the upper-layer ceramsite biscuit, the gamma values obtained by the near-well gamma detector (20) and the far-well gamma detector (21) are gradually reduced, and when the gamma values are just reduced from the stable highest value, the gamma values corresponding to the thickness of the slow-well gamma detector corresponds to the gamma-ray tracing effective radius R.
5. The method according to claim 1, wherein the effective radius of neutron activation in the step (6) is calculated by using a distance between a level gauge (32) and a moderator as r=h 0 -h i ,h 0 , which is a fixed value.
6. The method according to claim 1, wherein the capture gamma value ζ o per unit volume in the step (7) is ζ o =η/V,V= πR 2 H, and η is total capture gamma value.
7. The method according to claim 1, wherein the capture gamma value ζ Ceramic ware per unit volume in the step (9) is ζ Ceramic ware =kζ o , wherein k is a correction factor, k=v Sintering /V Biscuit , and k is smaller than 1.
8. The method of claim 1, wherein the measured value ζ Measuring of step (10) is a neutron activation prompt gamma signal value or signal-to-noise ratio detected during logging that varies greatly from tool parameter to tool parameter, borehole environment to well and hydrocarbon reservoir, and the measured value ζ Measuring is also variable from well logging environment to well.

Description

Preparation method of nonradioactive tracing ceramsite with stable signal-to-noise ratio Technical Field The invention belongs to the field of oil and gas exploitation auxiliary agents, and particularly relates to a preparation method of nonradioactive tracing ceramsite with stable signal-to-noise ratio for accurately describing a fracturing crack. Background The reserves of unconventional oil and gas resources such as Chinese shale oil and gas are very abundant, and the yield of the unconventional oil and gas in China is continuously increased in recent years, so that the unconventional oil and gas resources become countries with the fastest development steps of shale oil and gas exploration after the United states, and the production and storage increase effect is remarkable. The shale oil yield of 2022 China breaks through 300 ten thousand tons and is doubled compared with 2018, and the shale gas yield reaches 240 hundred million cubic meters and is 122 percent higher than 2018. Therefore, the increase of the unconventional oil gas exploration and development of shale oil gas and the like has important significance for guaranteeing the energy safety and optimizing the energy structure of China, and the hydraulic fracturing technology can obviously improve the overall permeability of the oil gas reservoir, so that the method is the most effective way for developing the unconventional oil gas reservoir of shale oil gas, compact gas and the like. The method has the advantages that the proppant position and the height, width azimuth and inclination angle of the near-wellbore fracturing fracture are accurately evaluated, the method has important value for the design of a fracturing model, the evaluation and optimization of unconventional oil gas and yield increase, and the method is an important support for efficient succession of resources in China. The near-well fracture diagnosis technology has important significance for evaluating the hydraulic fracturing effect, and is currently provided with near-well fracture monitoring technologies such as well diameter logging, array acoustic logging, nuclear logging and the like. Array sonic logging, while sensitive to fracture monitoring, has deviations in precision and accuracy. Temperature logging cannot directly reveal fracture height. Array sonic logging has shortcomings in directly revealing the proppant. Compared with the techniques, the nuclear logging has the advantages of wide monitoring content, high monitoring accuracy, high sensitivity and the like. Near-wellbore fracturing fracture nuclear logging has two techniques, radioactive tracer logging and non-radioactive tracer logging. The radioactive measurement technology adds radioactive tracer isotopes such as antimony, scandium, iridium and the like into propping agents or fracturing fluid, then performs logging before and after fracturing by utilizing natural gamma or natural gamma energy spectrum logging, and then compares the difference of gamma counts before and after fracturing, thereby realizing the acquisition of underground information of the fracturing fracture. The radioactive tracing well logging can use substances with certain radioactive intensity, the environment and people have radiation risks, the radiation risks do not meet the HSE requirements, the radiation tracing well logging is easy to be limited by the requirements of safety, environmental protection, transportation, storage and use, and the popularization is easy to be limited. Compared with the radioactive tracing well logging technology, the non-radioactive tracing ceramsite neutron capture gamma tracing well logging technology adds high capture section materials such as gadolinium, boron and samarium into propping agents. The method utilizes the actions of neutrons and propping agents, and before and after fracturing, a compensation neutron instrument (CNL) or a pulse neutron capture instrument (PNC) is used for logging, and the underground information such as the position and the height of a fractured crack is determined by comparing the thermal neutron count rate of a front detector, a rear detector, a far detector, the thermal neutron count rate of a capturing section or the change of a capturing section or calculating the capturing gamma count generated by a high-heat capturing section element. Accurate control of the concentration of the trace elements in the high neutron capture section is a key and precondition for success of a non-radioactive trace ceramsite neutron capture gamma trace logging technology. Too high or too low a trace element content may be a deterrent to logging applications of the technique. If the content of the trace element is too high, the cost of the trace ceramsite is obviously increased, and thus, large resource waste is caused. If the trace element content is too low, a low capture gamma signal to noise ratio may result, which may lead to logging failure. In the current preparation process of th