1225 results about "Drilling fluid" patented technology

The invention belongs to the technical field of drilling fluid, and particularly relates to a free radical polymerization water-based drilling fluid composition and a preparation method thereof. The invention relates to a core-shell composite particle-containing water reducer which comprises deionized water, salts (NaCl / KCl), alkalis (Na2CO3 and NaOH), barium sulfate and core-shell composite particles X. The particle is composed of a silicon dioxide core and a polymer shell layer, and the shell layer is formed by free radical copolymerization of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid and is covalently connected with the core through silanization treatment. Under the conditions of high salinity, strong alkali and high solid phase weighting, the drilling fluid simultaneously realizes the following effects: (1) high-density bearing and low-viscosity pumpability are realized; (2) compact plugging and water loss reduction and low formation damage flowback can be realized; and (3) stable rheology rock carrying, lubrication and friction resistance reduction. The problem that three aspects of performance are difficult to consider in the prior art is solved, and the drilling fluid is suitable for drilling of deep wells, ultra-deep wells and complex stratums and has remarkable industrial application value.

The invention provides a tool applied to the field of petroleum drilling, and particularly relates to an underground non-circular gear intelligent impact tool which comprises a power module, an axial impact module and a circumferential impact module, the power module enables drilling fluid to impact a turbine in a directional mode through a drainage disc, hydraulic energy is converted into mechanical energy, and the mechanical energy is transmitted to the axial impact module. The power is transmitted to the axial impact module and the circumferential impact module, the axial impact module lifts a rack punch hammer to compress a spring through meshing of an incomplete gear and the rack punch hammer, and when the incomplete gear is disengaged from the rack punch hammer, the spring releases energy to generate axial impact downwards. The circumferential impact module is composed of two groups of incomplete gears and racks which are arranged in an up-down 90-degree staggered mode, the rack punch hammer compresses a spring through meshing of the incomplete gears and the rack punch hammer, and the spring is released to generate circumferential impact when the incomplete gears and the rack punch hammer are disengaged. Periodic impact can be achieved, the mechanical rock breaking efficiency is effectively improved, and the stick-slip phenomenon at the drill bit is reduced.

The invention discloses a simulation experiment device and method for casing drilling, and relates to an experiment device and method for simulating the smearing effect of casing drilling, and the device comprises a simulation assembly and a manifold assembly. The simulation assembly comprises an experiment kettle, a simulation piece and a casing pipe nipple, and an annular gap is defined between the simulation piece and the casing pipe nipple. The manifold assembly and the annular gap form a flow loop of drilling fluid. The manifold assembly comprises a liquid storage tank, a pump body and a material storage tank, and the pump body and the material storage tank are arranged between the liquid storage tank and the inlet end of the annular gap. Wherein the storage tank can enable the rock debris to enter the annular gap along with drilling fluid pumped by the pump body, and the simulation assembly can enable the casing pipe nipple to rotate at a preset rotating speed under a preset axial acting force under a preset experiment condition, so that the rock debris entering the annular gap forms a mud cake on the inner surface of the simulation piece. The experimental device can be used for analyzing influence factors of the smearing effect of casing drilling and guiding on-site construction of the casing drilling, so that the smearing effect of the casing drilling can play a more remarkable effect.

The invention belongs to the technical field of drilling fluid processing, and particularly relates to a special silicate water-based drilling fluid for a coal-bed gas well as well as a processing method and a processing device of the special silicate water-based drilling fluid. The top end of the stirring tank is communicated with a first feeding hole and a second feeding hole, and the bottom end of the stirring tank is communicated with a discharging pipe; a rotating shaft is rotationally connected to the top surface of the inner wall of the stirring tank, and a sliding groove is formed in the bottom surface of the rotating shaft; a rotating shaft is driven by a first motor to rotate, and the rotating shaft drives a connecting shaft to rotate, so that fresh water and additives in a stirring tank are stirred and mixed by stirring blades, and a first screw rod can be driven by the first motor to positively and negatively rotate in a reciprocating manner in the mixing process; the first screw rod drives the connecting shaft to move up and down in the sliding groove, so that the stirring blades move up and down, the stirring blades stir and mix the water and the additive while moving, and the mixing efficiency and uniformity of the additive and the water are improved.

The invention discloses a high-temperature-resistant and high-pressure-resistant autonomous deep well pressure maintaining sampler, and belongs to the technical field of drilling engineering sampling. The sampler comprises an upper joint, a control outer pipe, an end cover, a valve body and a liquid storage chamber which are connected in sequence, an electromagnet is arranged on the outer side of the end cover; an electric control module is arranged in the control outer pipe; a valve element with a permanent magnet is arranged in the valve body in a sliding mode, the valve element is driven to move axially through non-contact electromagnetic force between the electromagnet and the permanent magnet, and opening and closing of the sampling flow channel are achieved. The bottom of the valve core is provided with a valve core inner channel communicated with the sampling flow channel and the liquid storage chamber and a one-way valve; a sampling inlet channel is formed in the joint of the end cover and the valve body. According to the invention, a pure mechanical sealing-based structure is adopted, so that the sealing reliability and the operation stability in a high-temperature and high-pressure environment of a deep well are remarkably improved, drilling fluid is not needed, and efficient and pressure-maintaining sampling of in-situ formation fluid is realized.

The invention belongs to the technical field of oil field drilling, and particularly relates to a preparation method of modified sulfonated phenolic resin for drilling fluid, and the modified sulfonated phenolic resin is prepared by chemically bonding a functional monomer simultaneously containing sulfonic acid anions and quaternary ammonium cations in a phenolic resin structure in a free radical polymerization mode. The quaternary ammonium cation group adsorbs negatively-charged clay particles, the adamantyl group can be adsorbed in hydrophobic areas of the clay particles through association, and the sulfonated phenolic resin can be quickly adsorbed on the surface of the clay in a double adsorption mode of hydrogen bonds and electrostatic attraction. Besides, a large number of sulfonic acid anions can form a compact solvation layer after hydration, and a compact coating film can be formed when phenolic resin is quickly adsorbed on the surface of clay, so that the clay is prevented from being in contact with water, the stability of clay particles is realized, a compact mud cake can be formed, and the prepared phenolic resin has good filtrate loss reduction performance.

A milling bit is disclosed for debris collection within a wellbore. A check valve can be part of a debris removal tool that includes a motor, a pump, a gearbox, a bailer, the milling bit, and rotational shafts. In an example, on its uphole end, the milling bit can be coupled with the check valve. On its downhole end, the milling bit can be configured for debris removal with cutting edges. The downhole end can also include openings that provide access to an internal cavity of the milling bit. The internal cavity can extend the entire length of the milling bit. This allows the pump to pull drilling fluid into the bailers through the milling bit and check valve. As a result, the debris removal tool can simultaneously remove obstructions in a wellbore and collect debris from the obstruction removal.

The invention belongs to the technical field of petroleum and natural gas drilling engineering, and relates to a rotary steering test method and system for simulating underground drilling fluid circulation in a workshop. The method comprises the following steps: firstly, determining a dynamic fingerprint and a tolerance band of a circulation channel of a target well section, wherein the dynamic fingerprint comprises a time domain step and a frequency domain phase index; constructing a test loop of a series-connected adjustable hydraulic dynamic equivalent module, wherein the module comprises a containing cavity, a throttling unit and an inertia pipe unit to regulate and control flexibility, damping and inertia; applying flow disturbance and collecting flow pressure data to obtain a current dynamic fingerprint; comparing the tolerance band to iteratively adjust module parameters until the fingerprint reaches the standard; and after locking the parameters, carrying out function testing. The problem that traditional testing is disjointed with underground working conditions can be solved, testing accuracy and reliability are improved, testing cost is reduced, and testing requirements of different well sections are met.

The invention discloses a surface lipophilic modified barite weighting material as well as a preparation method and application thereof, and belongs to the technical field of drilling fluids. The surface lipophilic modified barite weighting material comprises barite and a surface modifier, and the surface modifier comprises a copolymer formed by polymerizing a monomer A, a monomer B, a monomer C and a monomer D. According to the invention, the lipophilicity of the barite is chemically modified by the surface modifier, and all monomers have a synergistic effect, so that when the grafted and modified barite weighting material is used as the weighting agent of the oil-based drilling fluid, the dispersity and the stability of particles in the oil-based drilling fluid can be improved, and the rheological property, the plugging property and the high-temperature resistance of the drilling fluid can be adjusted.

The invention relates to the technical field of petroleum drilling engineering, and particularly discloses a drilling plugging agent as well as a preparation method and application thereof. According to the plugging agent, nano silicon dioxide and graphene oxide serve as a composite matrix, and the well drilling plugging agent with excellent dispersion stability, compact plugging performance, temperature resistance, salt resistance and reservoir friendliness is obtained through silane coupling agent graft modification and polymer copolymerization composite modification. The technical defects that an existing nano plugging agent is prone to agglomeration, poor in compatibility with drilling fluid, insufficient in extreme working condition resistance and the like are overcome, the preparation process is simple and controllable, the cost is relatively low, the plugging agent can be added into water-based or oil-based drilling fluid according to the mass ratio of 0.5-5%, the plugging agent is suitable for shale, deep high-temperature high-pressure high-salt complex stratums and the like, a compact plugging layer can be formed, and the plugging effect is good. Shale micro-cracks and deep stratum large cracks are effectively blocked, and the problems that a traditional blocking agent is prone to agglomeration, poor in extreme working condition resistance and the like are solved.

The embodiment of the invention relates to the technical field of petroleum machinery, and provides a pure sealing cavity integrated whipstock which comprises a whipstock body used for setting in a borehole, a sealing cavity, a sealing cavity and a sealing cavity. And the windowing milling cone is arranged on the whipstock and is provided with an inner cavity, the inner cavity is provided with a first communication port and a second communication port, and drilling fluid in the borehole can flow into the first communication port and is sent out from the second communication port, so that impurities in the drilling fluid in the borehole are taken away. Another embodiment of the invention provides a setting method which comprises the following steps: S1, drilling fluid reverse circulation: feeding drilling fluid carrying impurities at the to-be-set position of the borehole into the first communication port of the windowing milling cone, and feeding away the drilling fluid from the second communication port, so that the impurities at the to-be-set position are removed; and S2, drilling fluid positive circulation is conducted, specifically, drilling fluid is fed into a second communication port of the windowing milling cone and flows to the whipstock to enable the whipstock to be sealed. According to the technical scheme, the technical problem that the interior of the whipstock is prone to being polluted or blocked before the whipstock is set in the prior art is solved.

The invention relates to the technical field of drilling fluid treating agents, and discloses sulfonated asphalt for drilling fluid and a preparation method thereof.The preparation method of the sulfonated asphalt for the drilling fluid comprises the steps that asphalt is smashed and added into kerosene together with quaternization modified SEBS, reflux dissolution is conducted for 1-2 h at the temperature of 100-110 DEG C, when the temperature is reduced to 50-60 DEG C, fuming sulfuric acid is added, reaction continues for 2-3 h, and the sulfonated asphalt for the drilling fluid is obtained. And adjusting the pH value of the system to 8-9 by using a sodium hydroxide solution with the mass fraction of 20%, distilling and recovering the kerosene solvent, and drying and crushing the obtained solid in a drying oven to obtain the sulfonated asphalt for the drilling fluid. The sulfonated asphalt for the drilling fluid has good filtrate loss reduction performance at high temperature and high pressure, and also has good shale inhibition performance and borehole wall stability.

A liner mat for waste pit management and drilling fluid recycling at well sites is described. The liner mat includes an adsorbent layer and a base layer. The adsorbent layer includes chitosan and polyhydroxyalkanoate (PHA). The base layer includes polylactic acid (PLA). In some cases, the base layer includes hydroxyapatite (HAp). The adsorbent layer contacts the drilling fluid. The adsorbent layer can mitigate microbial growth and adsorbs at least a portion of pollutants from the drilling fluid. The base layer provides structural support and resistance against mechanical stress and tearing.

The invention provides a self-healing-shape memory phase change microcapsule for cooling drilling fluid as well as a preparation method and application of the self-healing-shape memory phase change microcapsule, and belongs to the technical field of cooling of the drilling fluid and underground heat management. The preparation method of the phase change microcapsule comprises the following steps: fully dispersing a polyurethane prepolymer, a polyimide solution and hydrophobic nanocellulose in an organic solvent to obtain an oil phase; dissolving a phase change material in deionized water to obtain a water phase; under a shearing condition, dropwise adding the oil phase into the water phase, and emulsifying to form a stable oil-in-water type Pickering emulsion; and adding an aqueous solution of a chain extender, and carrying out interfacial polymerization reaction, centrifugation, washing and drying. The phase change microcapsule disclosed by the invention shows excellent cyclic service performance under the underground high-temperature and high-shear conditions, and structure repair and morphology recovery can still be realized by virtue of self-healing and shape memory effects even if a shell layer is damaged, so that the service life of the phase change microcapsule is prolonged, and the cooling persistence of the drilling fluid is improved.

The invention discloses a high-performance thermosetting resin plugging material, a preparation method and a water-based drilling fluid, and relates to the technical field of oilfield chemistry, and the preparation method of the plugging material comprises the following steps: stirring an aromatic compound containing two double bonds with sodium tungstate, a transfer catalyst and a hydrogen peroxide solution at room temperature for reaction, and purifying to obtain an epoxy compound; the preparation method comprises the following steps: heating an aromatic compound containing an aldehyde group, ammonium formate and a palladium-carbon catalyst with nitrogen to react to obtain an amine compound, transferring the epoxy compound and the amine compound into a size-adjustable mold, carrying out heating curing treatment, carrying out low-temperature ball milling on a crude product to obtain plugging material particles, and preparing the water-based drilling fluid by using the plugging material particles. The specific aromatic rigid framework monomer is selected, and the molar ratio of epoxy to the curing agent is accurately controlled, so that the mechanical strength and thermal stability of the material are remarkably optimized, and the plugging material has a good treatment effect on cracks and pores in complex stratums.

The invention relates to the technical field of asphalt, and particularly discloses modified asphalt for drilling fluid and a preparation method of the modified asphalt, and the modified asphalt comprises the following components in parts by weight: 100 parts of matrix asphalt, 12-15 parts of sulfonated modified monomer, 3-5 parts of zwitterionic modified monomer, 2-3 parts of crosslinking modifier, 3-5 parts of environment-friendly activating aid, 2-4 parts of neutralization regulator and 90-110 parts of deionized water. The preparation method comprises the following steps: firstly, melting and activating the matrix asphalt, and adding the environment-friendly activating aid to prepare the activated asphalt; carrying out gradient heating, and adding a sulfonated modified monomer, a zwitterionic modified monomer and a cross-linking modifier step by step to complete composite cross-linking modification; and finally, cooling, adding a neutralization regulator to adjust the pH value, adding deionized water, performing high-speed shearing and homogenizing, and cooling to obtain a finished product. The modified asphalt is stable and controllable in viscosity, excellent in high and low temperature filtration loss control performance, adaptive to complex drilling working conditions, environment-friendly in process and easy to implement.

The invention discloses a seabed shallow casing section thermal insulation structure for polar region supercritical carbon dioxide drilling, which comprises a casing, a thermal insulation coating, a protective coating, an annular cement slurry layer, an electric heating pipe, a sensor module, a wireless conductive module, a ground system and a seabed wireless transmission module, and is characterized in that the electric heating pipe is fixed on the outer wall of the casing through a hoop; the outer wall of the casing pipe is sequentially coated with a heat preservation coating, a protective coating and an annular cement paste layer from inside to outside, the wireless conductive module is integrated at the end of the casing pipe, and the ground system comprises a ground data acquisition system and a ground control center. The sea surface platform is provided with a ground data acquisition system and a ground control center which are connected with the seabed wireless transmission module through an umbilical cable, and temperature and pressure data acquired by the sensor module are uploaded to the ground control center. According to the invention, the problems of rapid heat loss, annular air channeling, casing mechanical property degradation, poor drilling fluid fluidity and the like of the seabed shallow casing section in the polar region extreme low-temperature environment are solved.

The invention provides a well bottom ECD accurate determination method based on a field multi-point cycle test, and belongs to the technical field of petroleum and natural gas drilling engineering. Comprising the following steps: selecting at least three different-depth test points on a casing section, and synchronously obtaining pump pressure, drilling fluid rheological parameters and borehole-drill rod geometric data; preprocessing the data; calculating annulus pressure loss, drill rod pressure loss and drill bit pressure loss of each test point based on an API standard formula; establishing a pumping pressure-pressure consumption associated linear equation set and solving annulus and drill rod pressure consumption correction coefficients; and outputting a shaft bottom ECD for eliminating naked eye interference in combination with the real-time drilling parameters and the inversion coefficient. According to the method, the multi-point cycle test and the dynamic inversion model are combined, the deviation between the theoretical model and the actual working condition is quantified through the correction coefficient, the weighted least square and the matrix condition number pre-judgment technology are combined, the problem of ECD calculation misalignment of a traditional method is solved, and the pressure control precision and safety in a complex drilling scene are remarkably improved.

The utility model relates to the field of drilling fluid filtration, and provides a filtration device for drilling fluid sample analysis, which comprises a treatment tank, and the two connecting plates are fixedly arranged on one side of the treatment tank, and first positioning rods are movably embedded in the inner walls of the two connecting plates. During use, drilling fluid is poured into the treatment tank, impurities are filtered out through a filter plate, an external power switch of a driving motor is turned on, a rotating rod drives a plurality of push plates to rotate, and the drilling fluid is conveyed into the treatment tank; when drilling fluid is located on the filter plate, the push plates scrape the upper side of the filter plate, and when impurities in the liquid are accumulated in small holes in the filter plate, the push plates push the impurities to prevent the impurities from being accumulated to affect filtering of the liquid, so that when the drilling fluid is filtered, the impurities accumulated on the filter plate are pushed, and the filtering efficiency of the drilling fluid is improved.

The invention provides a nano plugging agent for a high-temperature-resistant shale oil gas water-based drilling fluid and a preparation method of the nano plugging agent, and relates to the technical field of drilling plugging agents. The nano blocking agent for the high-temperature-resistant shale oil-gas-water-based drilling fluid is a nano composite precursor aqueous dispersion which is stable at normal temperature, and can be triggered under the underground high-temperature condition and generate in-situ reaction in shale pores and on the surface to form an organic-inorganic hybrid blocking film. According to the technology, a conventional chemical raw material is converted into a high-performance plugging material in a low-viscosity precursor underground in-situ film forming mode, the industrial problem of efficient plugging of shale nano apertures is solved, and the core advantage is that the problem of a traditional physical accumulation mode is solved; a compact and tough organic-inorganic hybrid plugging film is formed in pores through temperature triggering, and plugging is changed into repairing.

The invention discloses a graft polymer and a preparation method and application thereof.The graft polymer comprises a structural unit I from graphene oxide, a structural unit II from a monomer A and a structural unit III from a monomer B. The value of the carbon element and the oxygen element of the graphene oxide is not larger than 2.5; the monomer A is a monomer containing a sulfonic acid group; the monomer B is a propenyl monomer containing a rigid group; the viscosity average molecular weight of the graft polymer is 75,000 to 120,000. The graft polymer disclosed by the invention can be used as an ultrahigh-temperature salt-resistant shear strength improving agent for water-based drilling fluid, the temperature resistance can reach 240 DEG C or above, the salt resistance can reach saturation, and the influence on the plastic viscosity of the drilling fluid is less while the shearing force of the drilling fluid is increased.

The invention provides a soilless phase reservoir protection water-based drilling fluid as well as a preparation method and application thereof, and belongs to the technical field of drilling fluids. The drilling fluid is prepared from the following raw materials in parts by mass: 100 parts of water, 0.2-0.4 part of a first pH regulator, 1-3 parts of a deoxidant, 0.1-0.4 part of a tackifying and shear strength improving agent, 2-4 parts of a filtrate reducer, 4-6 parts of magnesium-aluminum hydrotalcite, 4-6 parts of micro-nano aluminum oxide, 4-6 parts of superfine calcium carbonate, 4-6 parts of a lubricant, 1-2 parts of a corrosion inhibitor and 70-660 parts of an inorganic salt weighting agent. The drilling fluid disclosed by the invention is excellent in high-temperature resistance, good in rheological property and excellent in filtrate loss reduction performance; the drilling fluid disclosed by the invention can be prepared into saturated CaCl2 and saturated CaBr2 systems, does not contain barite and clay, is high in mud cake acid solubility, has permeability recovery of more than 72% after plugging, is good in reservoir protection, and has potential of on-site large-scale application.

The invention provides a drilling fluid flow monitoring device and method suitable for a mud runway, relates to the field of petroleum drilling ground testing instruments, and solves the problem that an existing monitoring method is low in overflow prediction precision and cannot find overflow in time. The device comprises a flow measuring unit (1), and the left side and the right side of the flow measuring unit (1) are connected with a flow guide unit (2) and a flow blocking unit (4) through flange plates respectively. The upper part of the diversion unit (2) is connected with the video monitoring unit (3); the flow measuring unit (1) is an electromagnetic flowmeter and is used for measuring the outlet displacement; the flow guide unit (2) is used for guiding drilling fluid to flow to the flow meter; and the flow choking unit (4) is used for controlling stable flow of the drilling fluid. According to the drilling fluid flow monitoring device suitable for the mud runway, real-time accurate monitoring of the flow of a drilling fluid outlet can be achieved, then monitoring of overflow and leakage of the drilling fluid is achieved, and well control safety is ensured.

The invention relates to the technical field of petroleum and natural gas drilling engineering, and particularly discloses a multi-field coupled complex fractured formation fracture width distribution inversion method, which is characterized in that a drilling fluid leakage model considering a fluid-solid coupling effect is constructed based on a porous elastic mechanics theory, and a roughness correction factor is introduced to correct a traditional cubic law; the application of the Darcy law in the matrix is perfected, a matrix and crack coupled drilling fluid leakage mathematical model is established, the influence rule of key parameters such as fluid viscosity, pressure difference and crack width on the drilling fluid leakage amount is obtained through numerical simulation, and on the basis, the drilling fluid leakage amount is calculated. According to the method, the crack width multiple linear regression inversion equation with the fluid viscosity, the pressure difference and the accumulated leakage as independent variables is established, the inversion equation has high prediction precision and practicability and can be used for rapidly and accurately inversing the crack width on site, and theoretical and technical supports are provided for multi-scale fractured formation leakage mechanism understanding and leakage prevention and control optimization.

The invention relates to the technical field of petroleum drilling fluid loss reduction, and discloses an anti-divalent salt fluid loss agent for drilling fluid, which is prepared by the following steps: step 1, beta-cyclohexylamine and 6-chloro-1-hexene are subjected to a reaction to obtain alkenyl beta-cyclohexylamine; step 2, initiating polymerization of alkenyl beta-cyclopentadiene, a hyperbranched monomer pentaerythritol triallyl ether and 2-acrylamide-2-methylpropanesulfonic acid under the action of azobis (isobutylamidine hydrochloride), so as to obtain an intermediate A; 3, 3-dimethylamino-1-propylamine and palmitic acid are subjected to a reaction, and an intermediate 2 is obtained; 4, the intermediate 2 and benzyl chloride are subjected to a reaction, and quaternary ammonium salt modified fatty acid is obtained; and 5, stirring and mixing the intermediate A, quaternary ammonium salt modified fatty acid and coupling agent modified walnut powder to obtain the divalent salt resistant filtrate reducer for the drilling fluid. The anti-divalent salt filtrate reducer for the drilling fluid has a relatively good anti-divalent salt effect.

The invention provides an adsorption pressure return type blowout control method, which comprises the following steps: intervening when well control abnormity occurs at the beginning (such as overflow precursor), compounding a methane adsorbent and a conventional drilling fluid additive to prepare high-density composite well control fluid, and injecting the high-density composite well control fluid into a shaft by a special device at a position 100-200m below a wellhead according to preset displacement and pressure parameters. According to the method, bubbles in a shaft are adsorbed through an adsorbent, the slippage speed and the gas phase volume fraction are reduced, and the synergistic effect of static pressure constraint and active adsorption is achieved. Therefore, back pressure fluctuation can be stabilized in the early stage of gas cut, gas column expansion and pressure rising are limited, the risk of pressure leakage and secondary eruption is reduced, the purpose of preventing or restraining blowout is achieved, and the gas cut blowout prevention device is suitable for complex working conditions such as fractured stratums, deep water, high temperature and high pressure and narrow-density windows.

The invention relates to the technical field of mud liquid level monitoring, and discloses a drilling mud liquid level monitoring and alarming device which comprises a drilling mud pool, the drilling mud pool is used for an oil and gas field drilling fluid circulating system, the drilling mud pool receives and deposits drilling fluid returned from a wellhead, and the drilling fluid is recycled by a mud pump after being treated; the monitoring module comprises a bearing frame, a liquid level monitoring assembly, a fluctuation response assembly and a cleaning control assembly; and the cleaning control assembly is associated with the fluctuation response assembly and the liquid level monitoring assembly and is configured to drive the cleaning control assembly to work so as to clean the surface of the receiving end of the photoelectric liquid level sensor when the fluctuation response assembly acts in response to fluctuation. Through the fluctuation response assembly and the cleaning control assembly, automatic cleaning of the liquid level monitoring assembly is achieved, and the problem that monitoring data are inaccurate or even invalid due to the fact that a traditional sensor is prone to contamination in a severe mud environment is effectively solved.

The application discloses a kind of well leakage risk early monitoring and early warning method, in the selection of calculating drilling fluid outlet flow moving average time period, time-frequency variation method is determined, so that the period contains the fluctuation characteristics of signal main, more scientific;Based on the comprehensive alarm method formed by moving average method and dispersion integral method, the sensitivity of the algorithm to the outlet discharge signal is ensured Reduce trend monitoring, while eliminating the risk false alarm caused by normal data fluctuations;The minimum value of the previous period dispersion integral is used to automatically generate a threshold, reducing the error caused by manually setting the threshold based on experience, and having good recognition effect in the early stage of well leakage.

The application provides a flexible plugging agent for offshore oil and gas drilling fluid and a preparation method and application thereof, and belongs to the technical field of offshore oil and gas drilling and production. The plugging agent is prepared from the following raw materials: styrene, N-phenylmaleimide, 2-acrylamido-2-methylpropanesulfonic acid, sodium p-styrenesulfonate, 2-methacryloyloxyethylphosphorylcholine, a crosslinking agent, an initiator, a hydrophilic emulsifier, an oleophilic emulsifier and water. The plugging agent has excellent structural stability, heat resistance, salt resistance and hydration stability, has good adaptability to a low-density drilling fluid system, has a flexible deformation capacity, can effectively enter a complex leakage passage to achieve effective plugging, and can maintain the integrity and stability of a plugging layer under drilling fluid circulation shearing, temperature fluctuation and complex downhole conditions, thereby having applicability in a high-temperature and high-pressure drilling environment.

The invention provides a drilling fluid and a preparation method thereof. The drilling fluid comprises the following raw materials: water, bentonite, sodium hydroxide, a filtrate reducer, an inhibitor, potassium chloride, a tackifier, a lubricant, a plugging agent, a film-forming agent and barite. Wherein the film-forming agent is prepared from the following raw materials in parts by weight: 50 to 60 parts of organic silicon solvent, 80 to 100 parts of ethanol water solution, 10 to 15 parts of polyurethane particles and 10 to 15 parts of nano silicon dioxide. The drilling fluid provided by the invention can prevent the drilling fluid or filtrate thereof from entering fine and micro-nano cracks of a shale well section, so that the influence of hydration or capillary force on a shale stratum is reduced, and the well wall stability problem in shale drilling can be fundamentally solved.