Solve the chemicals used in oilfield drilling, well completion, oil production, water injection, enhanced oil recovery, gathering and transportation, etc
Oilfield chemicals, also known as oilfield chemicals, refer to the chemicals used in the process of oilfield drilling, completion, oil production, water injection, enhanced oil recovery and gathering and transportation.There are many kinds of oilfield chemicals and classification methods. According to the type code standard of oilfield chemicals used in China's oil and gas industry, oilfield chemicals can be divided into six categories: general chemicals, chemicals for drilling, chemicals for oil and gas development, chemicals for enhanced oil recovery, chemicals for oil and gas gathering and transportation, and chemicals for water treatment.There are more than 300 kinds of domestic oilfield chemicals, with an annual consumption of more than 50000 tons.[1]
Chinese name
Oilfield chemicals
Mainly including
General chemicals
Category
Drilling mud treatment agent
Development
Consumption of domestic oilfield chemicals in 1995
It refers to a class of additives used in the process of oil and gas drilling, production and transportation, water quality treatment and enhanced oil recovery. It has a wide range of varieties, most of which are water-soluble polymers (such as vegetable gumpolyacrylamide, cellulose and biopolymers) and surfactants (petroleum sulfonates, alcohol or alkylphenol ethoxylates).The contents of oilfield chemistry research mainly include the preparation, performance evaluation (including basic theory), screening formula, construction design and field test of this chemical.Due to different reservoir conditions, crude oil, water quality and rock properties are different, and the chemicals (formulations) used are highly targeted.In order to develop and reasonably use oilfield chemicals, various disciplines (such as organic chemistry, inorganic chemistry, physical chemistry, chemical engineering, analytical chemistry, fluid mechanics, reservoir engineering and computational mathematics) are required.Oilfield chemistry has gradually become a new frontier science, which has been paid more and more attention.
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In recent ten years, China's oilfield chemical technology has developed rapidly, forming a broader market for oilfield chemicals.According to incomplete statistics, the consumption of domestic oilfield chemicals was 1.029 million tons in 1995, and by 2009, the consumption of the whole industry had reached 1.47 million tons.In the past 15 years, the use of oilfield chemicals has increased by more than 42%, and the market size has increased by more than 180%.Among them, the amount of drilling chemicals is the largest, accounting for 45% - 50% of the total amount of oilfield chemicals;Chemicals for oil production have high technical content, accounting for more than 30% of the total consumption.The reserves of newly discovered oilfields in China are limited, and the task of tapping the potential of old oilfields is arduous. In particular, according to the characteristics of China's oilfields, more new, efficient and pollution reducing oilfield chemicals are needed to strengthen oilfield exploration and development, improve oil recovery, and strengthen environmental protection.
Sinopec, PetroChina and CNOOC control the vast majority of oil and gas wells in China, and their special departments are generally responsible for the preparation of drilling fluid and technical services during the oil well exploitation.The concentration of China's drilling fluid technology service industry is high, and the market concentration of the top ten drilling fluid technology service enterprises is about 55%.Key enterprises engaged in drilling fluid technical services nationwide include Drilling Fluid Company of Great Wall Drilling Engineering Co., LtdChina Oilfield Services Co., LtdShengli Oilfield Drilling Engineering Technology Company, CNPC Chuanqing Drilling Engineering Co., LtdSichuan Renzhi Oilfield Technology Service Co., LtdEtc.Renzhi Oilfield Services is the largest private drilling fluid technology service enterprise in China.
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Drilling mud treatment agent
In order to maintain the excellent and stable performance of the mud and meet the needs of the drilling process, treatment agents (additives) must be added to all kinds of mud (water-based, oil-based, gas), especially when deep drilling or horizontal drilling is carried out in complex formations (such as collapse layer, salt gypsum layer).On the marketMud treatmentThere are as many as 2520 brands of agents, in fact, there are about 100-200 kinds of chemicals in them.According to the use of products, it can be divided into 16 categories, such as tackifier, fluid loss reducerCorrosion inhibitorDiluting dispersant, plugging agent, emulsifier, shale control agent, etc.In the late 1960s,Organic flocculant（polyacrylamide）And selective flocculant (copolymer of vinyl acetate and maleic anhydride).For example, in western Canada, the application of this flocculant increased the bit footage by 56%, the bit working time by 45%, and the mechanical footage by 12%;Since 1974, China has promoted the non dispersed mud system, which has increased the penetration rate by an average of 20%.In order to drill 7km deep wells (bottom hole temperature above 200 ° C) and geothermal wells (250 ° C), the compound of resin and lignite, styrene maleic anhydride copolymer and specially synthesized high temperature and salt resistant polymer can be added to water-based mud.The use of drilling mud treatment agent has accumulated a lot of experience. For low permeability oil wells, calcium bromide, zinc bromide, zinc chloride and other inorganic salts can be used to prepare a completion fluid with high relative density (up to more than 2.0) and no solid phase, which can double the oil production;Using foaming agent to prepare extra light mud can liberate low-pressure oil and gas reservoirs and remove lost circulation;Imidazoline corrosion inhibitor and polyformaldehyde bactericide can reduce corrosion loss and extend the life of drilling tools;The use of graphite, oil, hard asphalt and other lubricants can reduce the mud jam accidents;Emulsion mud can overcome the difficult drilling problems in complex formations;The use of anti pollution polymers can enable drilling tools to drill large sections of salt beds;Use thickener (polyacrylamideHydroxyethyl cellulose、Biopolymer）And diluent dispersant (ligniteLignosulfonatePhosphate) can adjust the flow pattern.Corresponding treatment agents are required to reduce filtration, stabilize shale and prevent formation damage.Hydrogen sulfide is a toxic gas. Adding sponge iron to mud can not only be used as an indicator of hydrogen sulfide, but also can quantitatively remove hydrogen sulfide to prevent corrosion and personal toxicity caused by it.
Chemicals for oil production
Chemicals used to extract oil from the bottom hole to the surface, including stimulation measures.It mainly includes paraffin remover, fracturing fluid, acidizing fluid and water shutoff agent.
① The wax remover willCrude oil demulsifierWhen it is added to the bottom of the well, it can prevent paraffin from depositing near the tubing wall and bottom of the well, thus reducing the number of paraffin removal times and boilers and making the oil well produce smoothly.In the past, organic solvents containing chlorine and sulfur were used as wax removers. These solvents are not only toxic to people, but also can poison refining catalysts. They are no longer used.
② When the permeability of the oil well production layer is low or seriously polluted by mud, fracturing fluid, acidizing and other stimulation operations should be carried out to improve the production capacity of oil and gas wells and the water absorption capacity of water injection wells.In order to open the formation, extend the fracture and carry the proppant, water-based, oil-based and acid based fracturing fluids are selected according to the reservoir conditions.Fracturing fluid first used river water, and later used thickened water, and has developed to use gel.Gelatin fracturing fluid is made of thickened water prepared by thickening agent and further thickened by cross-linking agent, which can improve the sand carrying capacity.The fracturing fluid contains enzymes and/orAmmonium persulfateIt is convenient to carry proppant to the destination, quickly reduce viscosity, and return to the ground.In the United States, guar gum (guar gum) is often used as a thickener. The chemically modified guar gum has little water insoluble residue and is fast in dissolution.Sesbania gum and guar gum in China have similar chemical composition（Galactomannan）, also used as thickener.usepolyacrylamideIt can be prepared into high viscosity and low residue fracturing fluid.
③ The acidizing fluid is mainly hydrochloric acid and mud acid (generally 8%~12% hydrochloric acid plus 2%~4% hydrofluoric acid mixed acid).For deep penetration, foam acid and emulsified acid are used. The latest delaying measure is to use high strength gel acid.In order to increase the ability of oil washing and suspended sludge, micellar acid is used.In order to inhibit acid corrosion, propargyl alcohol, imidazoline and quaternary ammonium salt are used as corrosion inhibitors.The dissolution rate of benzoic acid varies with temperature, which can block high permeability layers and sublimate, and can be used as acidizing diverter for oil and gas wells to make acid liquid enter the target layer.
④ When the water shutoff agent oil well is seriously out of water, it will cause water flooding and needs water shutoff.Water glass, calcium chloridepolyacrylamideThe gel can seal the water outlet layer.The selective water shutoff agent required for the same layer water is still under study.
Chemicals for gathering and transportation
Mainly includingCrude oil demulsifierAnti wax and pour point depressant, drag reducer and viscosity reducer.Crude oil contains water, which affects storage and transportation. Demulsifier and (or) high-voltage electric dehydration are often used.The first demulsifier used wasTurkish red oil。Modern effective demulsifiers are ethoxy ethers of alkyl phenols (or amines). Their action principles include flocculation coalescence, breaking the interface film, and liquid bead wrinkling and deformation.Oil soluble polymers, such as poly α - olefin and polyester, can reduce the flow resistance of turbulent crude oil and increase the throughput, which is calledDrag reducer for crude oil。Waxy crude oil has a high freezing point and is difficult to flow. Adding ethylene vinyl acetate copolymer can improve the fluidity of crude oil.The viscosity of heavy oil with more asphalt is very high, which makes it difficult to recover and transport. The viscosity of oil in water emulsion prepared with emulsifier is significantly reduced.
Chemicals for water treatment
Oilfield chemicals
If the salinity of oil production wastewater is relatively high and contains hydrogen sulfidecarbon dioxide, which will corrode the pipeline and pump of the treatment system and produce scaling and bacterial conjunctiva.Corrosion inhibitors such as fatty amine and imidazoline are often used for treatment.Phosphonate and polyacrylate are used for scale prevention.The main mechanism of anti scaling is solubilization, electrostatic repulsion, crystal deformity and dispersion.Corrosion inhibitor mainly works through adsorption film.The commonly used bactericide is acrolein or quaternary ammonium.Water for water injection system shall be oxygen free, and deoxidizer shall be added after mechanical evacuation.(See water treatment agent)
Chemicals for EOR
It mainly refers to the chemical agent used for chemical oil displacement.Chemical flooding can be divided into: ① polymer water flooding.Put a small amount of thickener (such asPartially hydrolyzed polyacrylamideOr biopolymer) dissolved in water to increase the viscosity of water, improve the fingering of water during injection, and improve crude oil recovery (Figure 1)Surfactant slug drive (Figure 2): surfactant slug is a microemulsion composed of petroleum sulfonate or synthetic sulfonate and activator alcohol. It has ultra-low interfacial tension (<10-8 N/cm), which can displace the crude oil in the capillary and improve the crude oil recovery.The biggest difficulty is to overcome the loss of surfactant when flowing in the reservoir (adsorption, capture, precipitation). ③Alkali water drive is to inject caustic water into the reservoir and react with the active components in the crude oil to form an emulsion to improve the crude oil recovery.
Overview abroad
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With the development of the petroleum industry, the consumption of oilfield chemicals is increasing. Its consumption has increased by 52% in ten years, and its value has increased by 96.1%.There are more than 70 categories and more than 3000 varieties of oilfield chemicals.North America is the region that consumes the most oilfield chemicals in the world, accounting for about half of the total. Among them, the United States is the country that consumes the most oilfield chemicals in the region. The annual consumption of oil production chemicals in the world is 4.5 million tons, worth 3.7 billion US dollars, accounting for 1/3 of the total consumption of oilfield chemicals.According to the statistics of 120 companies in the world, there are 988 chemicals used for oil production alone.
Since the 1970s, China's oilfield chemicals have made great achievements in their research, development and application, played an important role in oil exploration and development, and reached a considerable level in variety, quantity and quality.According to statistics, the annual consumption of petrochemical products nationwide is 1.2 million tons, of whichfine chemicals 350000 tons. It is estimated that the consumption of oilfield chemicals in China will increase at an annual rate of 10%, and the number of varieties has reached more than 300.Drilling mud materials are the largest amount of oilfield chemicals, accounting for about 45% - 50% of the total amount of oilfield chemicals, and their value accounts for more than 60%. However, the amount of chemicals used for oil production is high, accounting for 1/3 of the total consumption. These two types of chemicals play an important role in oilfield chemicals.
