[Petroleum Technology 481] The status quo, challenges, needs and development trends of drilling fluid technology
Status, Challenges, Demands and Development Trends of Drilling Fluid Technology
Sun Jin***********g Xiwen
(China National Petroleum Corporation Drilling Engineering Technology Research Institute, Beijing)
Abstract: This paper introduces the new progress of foreign drilling fluid technology, including well wall stability, leak prevention and plugging, high temperature drilling fluid, drilling fluid to improve mechanical drilling speed, low density drilling fluid, large displacement well drilling fluid, reservoir protection, green drilling fluid and other technologies, as well as the main achievements of China's drilling fluid technology during the "Eleventh Five-Year Plan" period, analyzes the main challenges facing current drilling fluid technology and the development needs of the "Twelfth Five-Year Plan", and discusses the development trend of drilling fluid technology.
In recent years, drilling fluids have played an increasingly prominent role in ensuring drilling safety, stabilizing well walls, improving drilling speed, and protecting reservoirs. However, with the increasing number of deep wells, ultra-deep wells, and special process wells in complex formations, people have put forward higher requirements for drilling fluid technology. To this end, a large number of applied basic theory and new technology studies have been carried out abroad, and a series of research results and application technologies have been achieved. During the "Eleventh Five-Year Plan" period, China's drilling fluid technology has also made great progress, but there is still a gap compared with foreign countries.
Therefore, in order to better provide high-quality and efficient drilling fluid technology for drilling operations, and also provide a scientific basis for the development direction of China's "12th Five-Year Plan" drilling fluid technology, the status quo, challenges, needs and development trends of drilling fluid technology are outlined.
New progress in drilling fluid technology abroad
1.1 Wall stabilization technology
1.1.1 High Performance Water-based Drilling Fluid Technology
Major foreign drilling fluid companies have developed a high-performance water-based drilling fluid (HPWM) that can replace oil-based and synthetic-based drilling fluids in terms of performance, cost and environmental protection. Its typical formula is as follows.
(2%~ 4%) polyamine compound + (1%~ 2%) aluminate complex + (2%~ 4%) drilling rate enhancer + (2%~ 3%) polymer (deformable plugging agent) + (0.2%~ 0.4%) modified starch + (0.15%~ 0.3%) XC + (0.1%~ 0.2%) PAC.
Representative technologies include M-I's ULTRADRIL system and Halliburton-Browder's HYDRO-GUADR system.
In the drilling fluid system, the amine group of the polyamine salt is easily adsorbed preferentially by the clay, which promotes the dehydration between the clay crystal layers and reduces the hydration expansion; the aluminate complex can form precipitation after entering the interior of the shale, combine with the formation mineral matrix, and enhance the stability of the well wall; the drilling speed enhancer can cover the drilling cuttings and metal surfaces to prevent the mud bag of the drill bit; the deformable polymer plugging agent can match the micropores of the shale to form a tight filling.
Baker Hughes Drilling Fluid Company combines the turbidity point of polyamine compound with polymeric alcohol and the chemical reaction of aluminum to form a PERFORMAX high-performance water-based drilling fluid system. The system uses the combined action of plugging polymer MAX-SHIELD, aluminum compound MAX-PLEX, hydration inhibitor MAX-GUARD and polymer coating agent NEW-DRILL to plug mudstone pores and micro-cracks, prevent the intrusion of drilling fluid filtrate, reduce the transfer of pore pressure, and greatly improve the inhibitory properties of water-based drilling fluid.
The field application results in the Gulf of Mexico, the continental United States, Brazil, Australia, Jidong, Nanhai and other places in China show that the high-performance water-based drilling fluid has the characteristics of strong inhibition, improved mechanical drilling speed, high temperature stability, reservoir protection and environmental protection.
1.1.2 film-forming water-based drilling fluid technology
By adding a film-forming agent to the water-based drilling fluid, the drilling fluid forms a high-quality film on the surface of the shale well wall to prevent the drilling fluid filtrate from entering the formation, thus playing a similar role to the oil-based drilling fluid in protecting the reservoir and stabilizing the well wall. According to the reports of CSIRO (Commonwealth Scientific and Industrial Research Organization) and Baroid, they have developed three new compounds with film-forming efficiency, and their film efficiency is between 55% and 85%. On this basis, a new water-based drilling fluid with high film efficiency has been formed, and good application results have been achieved in the field.
At present, several drilling fluid systems have been confirmed to have film-forming effects, namely: ① polymeric alcohol drilling fluid system; ② methyl glucoside drilling fluid system; ③ silicate drilling fluid system, among which silicate drilling fluid system has the best membrane efficiency.
1.1.3 well wall "film" technology or well wall "lining" technology
The Schlumberger Cambridge Research Center has proposed a well wall "film" (or well wall "lining") technology, that is, the use of the photocuring reaction properties of resins to generate wellbore lining on the well wall, that is, the well wall "film". It is a new technology that integrates stabilizing the well wall, preventing leakage and plugging, improving formation pressure and protecting the reservoir.
The technology first transports the light-sensitive resin material to the well through a tool that can be continuously rotated, contains a light guide tube, and has holes. The ejected resin material can remove the virtual mud cake on the well wall. At the same time, the light-curing reaction of the resin can quickly solidify to form a layer of "film" similar to wallpaper, which is called the remote-controlled wellbore liner technology. The polymerization of the resin on the well wall can be adjusted according to actual needs, and the "film" formed on the well wall can be seen through real-time image transmission. The film has good elasticity and strong pressure-bearing capacity, which can stabilize the well wall, improve the pressure-bearing capacity and protect the reservoir
Purpose.
1.1.4 oil-based drilling fluid technology
1) An oil-based drilling fluid with flat rheological properties. M-I company has developed an oil-based drilling fluid for deepwater drilling, large-displacement wells and has flat rheological properties. The system is composed of a small amount of organic soil, an appropriate amount of tackifier, emulsifier, flow pattern regulator, etc. Its rheology is not affected by temperature and pressure, the amount of filtration loss is small, and the well hole purification ability is strong. It can effectively protect the reservoir and solve the problems of bottom hole cleaning ability decline caused by temperature and other environmental changes, excessive annular equivalent circulation density, barite sedimentation and well leakage, and meets the requirements of environmental protection.
2) Low solid-phase mineral oil-based drilling fluid. The drilling fluid uses calcium bromide brine as the dispersed phase, standard mineral oil as the continuous phase, and liquid resin organic matter replaces natural asphalt as the fluid loss agent. The basic formula is as follows.
423 kg/m3 low aromatic mineral oil + 30kg/m3 emulsifier + 10 kg/m3 liquid fluid loss reducer + 10 kg/m3 high-quality organic soil + 161 kg/m3 clear water + 364 kg/m3 calcium bromide brine (density 1.7 kg/m3) + 10kg/m3 lime field application in Aasgard oilfield in central Norway shows that compared with traditional drilling fluids, the drilling fluid has better plugging and thermal stability, short wellbore purification time and good reservoir protection effect
3) High-density low-solids oil-based drilling fluid. M-I company prepared a low-solids oil-based drilling fluid with a density of 1.66 g/cm3 with cesium formate brine. The basic formula is as follows.
The field application effect of 360 L/m3 base oil + 590 L/m3 cesium formate brine + 35 L/m3 emulsifier + 2 kg/m3 lime + barite in Statfjord oilfield shows that the difference between this drilling fluid and conventional oil-based drilling fluid is that the solid content is reduced from 22% to 1%, the borehole instability does not occur, the formation damage is small, and the well productivity can be improved.
4) Oil-based drilling fluid without organic soil. Halliburton Browder has reported an oil-based drilling fluid without organic soil. Its basic formula is as follows.
0.075 m3 linear paraffin + 34.2 kg/m3 emulsifier + 8.55 kg/m3 lime + 28.5 kg/m3 polymer fluid loss reducer + 1.425 kg/m3 modified fatty acid + 0.02 m3 water + 43.6 kg/m3 calcium chloride + 22.8 kg/m3 fiber tackifier + 1 484.85 kg/m3 trimanganese tetroxide.
The field application results show that the drilling fluid can solve the settlement problem of barite under the conditions of high pressure, high temperature (204 ℃) and high density (2.2 g/cm3), and can reduce the equivalent circulation density in large-displacement wells.
5) Solid-free drilling/completion fluid. Baker Hughes Drilling Fluids has developed a solid-free drilling/completion fluid composed of paraffin, emulsifier, wetting agent, oil, calcium chloride and calcium bromide brine. The system can be used for drilling in active shale and gravel packing fluid in horizontal wells. The density can be adjusted by changing the oil-water ratio, CaCl2 or CaBr2 aqueous phase density.
1.2 Leak prevention and plugging technology
1.2.1 plug for severe leakage
M-I Company has developed a FORM-A-SQUEEZE plugging plug, which can be used to solve various fractures and hole formation leakage and blowout accidents. When the prepared high-filtration/high-solids drilling fluid passes through the leakage layer, the liquid phase squeezes the drilling fluid to quickly form a mud cake sealing plugging layer. The temperature resistance can reach 232 ° C and the environment is friendly. The plugging effect is not affected by the setting agent, retarder, temperature and time.
Halliburton Browder has developed a plugging agent FlexPlug that can stop severe or complete drilling fluid leakage, interlayer cross-flow and blowout. Its plugging effect is achieved by the chemical reaction between the plugging agent and the drilling fluid. The reaction is fast and saves drilling time. It does not require drilling. It can quickly form a plugging plug after mixing with the drilling fluid under the drill bit, resulting in a plugging effect.
Baker Hughes Drilling Fluids has developed a rigid gel bridge plug X-LINK, which is a mixture of cross-linked polymer and bridge plugging agent. It can form a very strong rigid colloidal plug after being pumped into the leakage layer, which can be applied to severe leakage in layers such as conglomerate with poor cementation and limestone with fractures. The product is non-toxic and environmentally friendly. It can control the crosslinking rate and time with retarders and accelerators according to temperature. There is no need to drill and change the drilling tool combination, and the formed colloidal plug can be easily drilled through and separated by a vibrating screen.
1.2.2 elastic graphite materials
Elastic graphite is a material with elastic, water chestnut and two-component carbon structure. Under the compression state of pores and micro-cracks, it can shrink first and then expand. It has good elasticity, deformability, toughness and chemical stability. It can adaptively seal pores or cracks of different shapes and sizes under the dual action of expansion filling and internal compaction. Representative products include STEELSEAL from Halliburton Browder Company, LC-LUBE from Baker Hughes Drilling Fluid Company and Rebound from Phillips Company.
1.2.3 wellbore reinforcement technology
The method of increasing the strength of the borehole wall and effectively improving the fracture resistance of the formation is proposed abroad to strengthen the permeable and non-permeable formations, so as to increase the wellbore stability window and drill with a higher drilling fluid density without leakage. This method provides a new idea for solving the problem of leakage in the drilling process.
In order to achieve the purpose of wellbore reinforcement, it is necessary to form small cracks by squeezing the rock around the wellbore like a wedge, and the suitable solid-phase plugging material in the drilling fluid quickly enters the fracture and forms a bridge plug near the crack opening. The bridge plug penetration rate must be low enough to block the transmission of liquid column pressure, and produce a "stress cage" effect that can seal the fracture, prevent the further expansion of the fracture, prevent the pressure from being transmitted to the end of the fracture, and increase the stress around the wellbore, so as to achieve the effect of leakage prevention and plugging.
Representative wellbore reinforcement technologies include M-I's integrated wellbore reinforcement technology I-BOSS and Halliburton Browder's WellboreStress Management technology.
1.3 High temperature drilling fluid technology
1.3.1 high temperature treatment agent
M-I company has developed a polyvinyl pyrrolidone PVP, which can make drilling fluid have good shear dilution and carrying capacity, and resist temperature up to 180 ° C; M-I company has also developed a molecular weight of 500,000~ 1 million copolymer Hosta-drill4706, which can improve the rheology of drilling fluid and resist temperature up to 230 ° C; M. Samuel and others have developed a zwitterionic surfactant VIS-PILL, which can be used as both a tackifier and a fluid loss reducing agent, with a temperature resistance of 190 ° C; Md. Amanullah and others have extracted GSP from natural materials as a high temperature protective agent, which can prevent bentonite
The drilling fluid is thermally degraded at a high temperature above 150 ° C; Luigi F. et al. developed a zirconium citrate anti-high temperature viscosity reducer ZRC, which can control the high temperature gelling of bentonite above 204 ° C and improve the thermal stability of other treatment agents; The United States reported the processing agents COP-1 and COP-2 synthesized by the copolymerization of AMPS, SMP and AM, with a temperature resistance of 262 ° C; Germany reported the synthesis of sodium, lithium, magnesium and oxygen composed of multilayer silicon SIV, with a thermal stability of 370 ° C. Its structure is similar to that of natural expansive microcrystalline kaolinite
The prepared drilling fluid system has a temperature resistance of 233 ℃.
1.3.2 high temperature drilling fluid system
1) Formate solids-free drilling fluid. Common treatment agents have good compatibility in formate drilling fluids, and formate can improve the high temperature stability and thermal stability of polymers. Mobil has successfully applied formate drilling fluid for the first time to drill high-temperature and high-pressure wells. In the Walsrode area of Germany and the Belanak oilfield in Indonesia, the temperature of high-temperature and high-pressure wells reached 162.8 ° C and 157 ° C respectively. The application of formate solids-free drilling fluid as base slurry drilling has achieved good application results.
2) Bentonite-free high-temperature drilling fluid. M-I has developed a bentonite-free high-temperature drilling fluid system that can maintain stability at 180~ 220 ° C. It is composed of vinamide-sulfonated ethylene copolymer, modified clay, calcium carbonate of different particle sizes, magnesium oxide, etc. The drilling fluid has achieved good application results in five high-temperature and high-pressure wells in the Kalinovache and Molve gas fields.
3) High-temperature silicate drilling fluid. Schlumberger has developed a high-temperature silicate drilling fluid system, which uses copolymers that can remain stable at 163 ° C and high pH as high-temperature polymers. The basic formula is as follows.
1.4% KCl + 0.07% Na2CO3 + 0.285% conventional PAC + 0.3% Ulpac + 4.2% high temperature polymer + 0.2% XC + 2.282% sodium silicate + modified asphalt + 1.14% amine-based high temperature diluent The drilling fluid has good reproducibility, and the filtration loss at high temperature and high pressure at 160 ° C is only 5 mL, and the inhibition is strong.
4) High temperature resistant polymeric alcohol drilling fluid. M-I company has developed a high temperature resistant polymeric alcohol drilling fluid, which is composed of polymeric alcohol, anti-flocculant, fluid loss reducing agent, polymer high temperature stabilizer and low molecular weight polymer viscosity reducing agent. The drilling fluid has stable performance, low static shear force and strong anti-pollution ability. It has achieved good application results in Yacheng 21-1-4 Well in Hainan, China, with a bottom temperature of 212 ° C.
5) High temperature resistant SIV drilling fluid. A heat is added to the SIV drilling fluid