阅读说明：本技术 高温高密度海水基钻井液 (High-temperature high-density seawater-based drilling fluid ) 是由 谢丽君 班士军 孙德民 李海洋 邹龙 张永胜 赵晨 于 2019-01-09 设计创作，主要内容包括：本发明为海洋石油勘探开发过程中的钻井液,特别是具有超高密度的抗高温钻井液,其各组分配比为膨润土1-3%,凹凸棒石1-3%,抗高温聚合物降失水剂3-6%,聚合物降粘剂0.15-0.3%,高温保护剂1-2%,抗温润滑剂3-5%,乳化剂0.2-0.5%,碱度控制剂0.15-0.3%,钻井液用加重剂15-40%,纳米封堵剂2-4%,海水36-73%。本钻井液抗高温能力达到200℃以上,可控密度达2.5g/cm<Sup>3</Sup>。它具有较强的抗钙、抗镁、抗劣质土污染的能力；高温下良好的流变性,失水量低；该钻井液体系油层保护效果好,岩心渗透率可以达到90%以上,特别适合深井、超深井的钻探。(The invention relates to a drilling fluid in the process of marine oil exploration and development, in particular to a high-temperature resistant drilling fluid with ultrahigh density, which comprises 1-3% of bentonite, 1-3% of attapulgite, 3-6% of high-temperature resistant polymer fluid loss additive, 0.15-0.3% of polymer viscosity reducer, 1-2% of high-temperature protective agent, 3-5% of temperature resistant lubricant, 0.2-0.5% of emulsifier, 0.15-0.3% of alkalinity control agent, 15-40% of weighting agent for drilling fluid, 2-4% of nano plugging agent and 36-73% of seawater. The drilling fluid has high temperature resistance up to 200 deg.c and controllable density up to 2.5g/cm 3 . It has strong calcium, magnesium and poor soil pollution resistance; good rheological property at high temperature and low water loss; the drilling fluid system has good oil layer protection effect, the core permeability can reach more than 90 percent, and the drilling fluid is particularly suitable for drilling deep wells and ultra-deep wells.)

1. The high-temperature high-density seawater-based drilling fluid comprises the following main components:

1 to 3 percent of sodium bentonite

1 to 3 percent of attapulgite

3 to 6 percent of high temperature resistant polymer fluid loss agent

1 to 2 percent of high-temperature protective agent

3 to 5 percent of temperature resistant lubricant

0.2 to 0.5 percent of emulsifier

Alkalinity controlling agent 0.15-0.3%

0.15 to 0.3 percent of viscosity reducer

The weight additive for drilling fluid is 15-40%

2 to 4 percent of nano plugging agent

36 to 73 percent of seawater.

2. The high-temperature high-density seawater-based drilling fluid is characterized in that sodium bentonite and attapulgite are compounded to serve as base slurry, the attapulgite is clay mineral with a layer-chain transition structure and mainly containing water-containing magnesium-rich silicate, is natural inert, has low cation exchange capacity, has a crystal structure unchanged at high temperature, cannot be flocculated by electrolyte in brine, and has high-temperature resistance.

3. The high-temperature high-density seawater-based drilling fluid according to claim 1, wherein-COOH and-SO with strong hydrophilic ability are introduced during synthesis of the high-temperature resistant polymer fluid loss additive₃ ^-In particular-SO₃ ^-The high-temperature dehydration agent still has strong hydration capability at high temperature, weak dehydration effect at high temperature and good fluid loss reduction effect at high temperature.

4. The high-temperature high-density seawater-based drilling fluid according to claim 1, wherein the used high-temperature protective agent can reduce the content of an oxidation group in the drilling fluid, increase the oxidation resistance of a polymer in the high-temperature-resistant drilling fluid, and maintain the good rheological property of the drilling fluid.

5. The high-temperature high-density seawater-based drilling fluid according to claim 1, wherein the used lubricant has good film-forming adhesion and oxidation resistance at high temperature.

6. The high temperature high density seawater-based drilling fluid of claim 1, wherein the alkalinity controlling agent used is sodium hydroxide.

7. The high-temperature high-density seawater-based drilling fluid is characterized in that the used viscosity reducer is an organic silicon-fluorine viscosity reducer, so that the temperature-resistant chemical stability and the good rheological property of a drilling fluid system are improved.

8. The high-temperature high-density seawater-based drilling fluid according to claim 1, wherein the nano plugging agent is a resin variable plugging agent.

9. The high-temperature high-density seawater-based drilling fluid as claimed in claim 1, wherein the weighting agent is sodium formate and microcrystalline barite.

Technical Field

The invention relates to a drilling fluid used in the exploration and development process of marine oil and natural gas, in particular to a high-temperature resistant drilling fluid with ultrahigh density.

Background

With the development of the petroleum industry and the increasing demand for petroleum, oil and gas exploration and development gradually excavate towards oceans and deep levels, and the drilling scale of deep oceans and ultra-deep oceans is gradually enlarged. Meanwhile, drilling of deep wells and ultra-deep wells becomes an important mark for development of the drilling industry in the future, and is also an important measure for expanding new fields of oil and gas exploration and development. With the increase of the well depth, the difficulty of the drilling technology is gradually increased, and the requirement on the performance of the drilling fluid is higher. Drilling practices show that the performance of the drilling fluid plays a crucial role in ensuring safe and rapid drilling of deep wells and ultra-deep wells. The drilling fluid technology of deep wells and ultra-deep wells is one of the determining factors concerning success and failure of drilling of deep wells and the quality of drilling of deep wells, and is the main subject of research of drilling fluid workers at home and abroad at present.

The main problems of the high-temperature high-density seawater-based drilling fluid at present are that ① is poor in thermal stability and difficult to maintain, and the drilling fluid system is subjected to aging at high temperature (above 200 ℃) for a certain time, so that the performance of the drilling fluid system is difficult to maintain in a good state, and the phenomenon that engineering requirements cannot be met is caused³) ② high temperature and high pressure loss of water and wall building are difficult to control, wherein the rapid increase of HTHP loss of high temperature and high density drilling fluid after aging is a general phenomenon, the phenomenon is more prominent when the temperature is higher, the salinity is higher, and the density is higher³When the density is more than 2.2g/cm, the HTHP water loss is obviously increased³Later, the HTHP water loss is multiplied, more types of filtrate reducers must be added, and the dosage needs to be further increased to solve the problem, so that the types and the dosage of the filtrate reducers for the high-temperature drilling fluid are greatly increased, the density of ③ is more than 2.2g/cm³The rheological property of the high-density drilling fluid is difficult to control. Because of the existence of a large amount of barite particles in the high-temperature high-density seawater-based drilling fluid, the friction force among solid phase particles is increased, and the viscosity of the drilling fluid is greatly increasedAdditionally, if the amount of soil in the drilling fluid is controlled slightly improperly, the viscosity and shear force increase after high-temperature aging, which results in loss of fluidity (high-temperature gelation and high-temperature solidification) and difficulty in limited viscosity reduction.

The low-density drilling fluid meets the requirement and is weighted to 2.00g/cm³Above all, the poor wall-forming property (especially HTHP water loss) and rheological property of the drilling fluid are required to be readjusted, which is a common problem of the temperature-resistant and salt-resistant high-density drilling fluid. And the performance of the drilling fluid with medium and high density is more difficult to maintain and treat stably (the key point is that the normal temperature viscosity is too high and the high temperature viscosity is low), which is another problem commonly existing in the drilling fluid with high density and high temperature resistance and salt resistance. The high temperature resistant technology of the drilling fluid becomes a technical bottleneck for restricting exploration and development of petroleum and natural gas resources in deep stratum. Therefore, the development of the high-temperature and high-density seawater-based drilling fluid technology which can resist the high temperature of more than 200 ℃ and is suitable for various densities has important significance for accelerating the exploration and development of petroleum and natural gas resources of Chinese deep strata, particularly ocean deep strata.

Disclosure of Invention

One of the purposes of the invention is to solve the problems and provide a high-temperature high-density seawater-based drilling fluid with strong high-temperature resistance and high density controllable range, wherein the drilling fluid has the advantages of polymer drilling fluid in the aspects of improving drilling speed, inhibiting formation slurry making, improving stability of well walls and the like, and has the advantages of good thermal stability, rheological property, low water loss and the like of sulfonated drilling fluid.

The high-temperature high-density seawater-based drilling fluid comprises the following components:

1 to 3 percent of sodium bentonite

1 to 3 percent of attapulgite

3 to 6 percent of high temperature resistant polymer fluid loss agent

1 to 2 percent of high-temperature protective agent

3 to 5 percent of temperature resistant lubricant

0.2 to 0.5 percent of emulsifier

Alkalinity controlling agent 0.15-0.3%

0.15 to 0.3 percent of viscosity reducer

The weight additive for drilling fluid is 15-40%

2 to 4 percent of nano plugging agent

36 to 73 percent of seawater

The bentonite in the solution of the invention has the functions of ensuring that the drilling fluid has certain dispersion degree, improving the viscosity of the drilling fluid, effectively carrying rock debris and purifying a well hole; the attapulgite is a clay mineral with a layer chain transition structure and mainly containing water-containing magnesium-rich silicate, has natural inertia, low cation exchange capacity and unchanged crystal structure at the temperature of 350-400 ℃, so that the attapulgite cannot be flocculated by electrolyte in salt water and has high temperature resistance; the high temperature resistant filtrate reducer contains adsorption groups including carboxyl-COO-, amido-CONH₂hydroxyl-OH, and the like. Simultaneously introduces-COOH and-SO with strong hydrophilic ability₃ ^-In particular-SO₃ ^-The copolymer still has strong hydration capability at high temperature, the high-temperature dehydration effect is weak, and the copolymer still has good solubility even in saturated saline; the high-temperature protective agent has the functions of improving the high-temperature resistance of each component of the drilling fluid and removing dissolved oxygen in the drilling fluid, so that the high-temperature high-density seawater-based drilling fluid system has good stability and rheological property under the high-temperature condition; the temperature-resistant lubricant can effectively improve the lubricating property of the drilling fluid at high temperature and keep the good rheological property of the drilling fluid; the emulsifier adopts span 80 (SP 80), and has the functions of forming water-in-oil with seawater and oil, improving the dispersion degree of the oil, effectively improving the temperature resistance and lubrication capacity of the lubricant for the drilling fluid, and reducing the frictional resistance of the drilling fluid; the alkalinity control agent has the function of adjusting the pH value of the drilling fluid, so that the composition of a drilling fluid system can better exert the filtration loss reduction performance, the dilution performance and the rheological stability performance under a certain pH value; the viscosity reducer is an organic silicon fluorine polymer viscosity reducer, and has the function of properly reducing the dispersion degree and viscosity of the drilling fluid, so that the drilling fluid has stable viscosity-shear and rheological properties; the weighting agent for the drilling fluid selects soluble salt as a weighting inhibitor and microcrystalline barite as the weighting agent.

The high-temperature high-density seawater-based drilling fluid has the advantages that the high-temperature high-density seawater-based drilling fluid resists the temperature of 200 ℃, the high-temperature high-pressure filtration loss is less than or equal to 20m L after being aged for 16 hours, and the density can reach 2.5g/cm³. The drilling fluid is creatively prepared by compounding sodium bentonite and attapulgite as a clay phase, combines the temperature and salt resistance characteristics of the attapulgite, improves the problem of drilling fluid performance deterioration caused by high temperature when the content of the bentonite is high, and has good inhibitive performance and rheological property. The drilling requirement of deep wells and ultra-deep wells is met, and the performance indexes are shown in the following table:

the data in the table show that the high-temperature high-density seawater-based drilling fluid resists the temperature of 200 ℃, after aging for 16 hours, the high-temperature high-pressure filtration loss is less than or equal to 20m L, and the density can reach 2.5g/cm³The drilling fluid has excellent rheological property and can meet the requirements of marine drilling construction.