CN112063375A - High-temperature-resistant high-density oil-based well completion fluid and preparation method thereof - Google Patents

Abstract

The invention provides a high-temperature resistant and high-density oil-based well completion fluid and a preparation method thereof, belonging to the technical field of petroleum exploration and development. The high-density oil-based completion fluid is prepared by including the following raw materials in parts by weight: 80-90 parts of white oil, 10-20 parts of calcium chloride aqueous solution, 20-30 parts of main emulsifier, and 10-20 parts of auxiliary emulsifier parts, 5-10 parts of organic soil, 5-10 parts of cutting agent, 10-15 parts of wetting agent, 25-30 parts of fluid loss reducer, 5-10 parts of calcium oxide, and 150-200 parts of weighting material. The product obtained by the invention has good quality stability, the product particle size D50 is less than 1.5 microns, the product temperature resistance can reach above 240°C, the product density can reach above 2.5g/cm3, and the product can be guaranteed to have good quality for 15-20 days under high temperature conditions. Rheology and suspension stability, do not pollute the formation, and can be reused.

Description

A kind of high temperature resistant and high density oil-based well completion fluid and preparation method thereof

technical field

The invention belongs to the technical field of petroleum exploration and development, and in particular relates to a high-temperature-resistant and high-density oil-based well completion fluid and a preparation method thereof.

Background technique

At present, oil drilling continues to develop into deep formations, with more and more wells reaching depths of more than 6,000 meters. As the drilling depth increases, the bottom hole temperature is getting higher and higher, and more and more high-pressure formations are drilled. The bottom hole temperature of some wells reached 200°C, and the formation pressure coefficient reached 2.30. Completion fluids face the challenge of high temperature and high pressure. High-density drilling and completion fluids need to add a large amount of solid weighting materials to increase the density, resulting in high solids content in drilling and completion fluids. Completion operations require high-density completion fluids with good properties. Generally, the viscosity of oil-based completion fluid decreases under the action of high temperature, and the high-density solid phase is easy to settle under the action of gravity. In field applications, the basic contradiction between the high temperature rheology and settlement stability of completion fluids is difficult to control.

After completion of wells in the southern margin of the Junggar Basin, Xinjiang, the formation pressure coefficient is high, requiring higher drilling fluid density, stronger resistance to temperature and various contamination (comprehensive contamination of saturated salt, gypsum, and drill cuttings). The particle size of conventional weighting agents (such as barite powder) is usually between 10 μm and 70 μm. During the application process, the phenomenon of high barite sedimentation rate and uneven density of drilling fluid often occur. In order to solve its suspension problem, it is usually necessary to add a large amount of treatment agent. However, with the increase of the amount of treatment agent, the cost of drilling fluid rises sharply on the one hand; on the other hand, the rheology of drilling fluid deteriorates and is difficult to control, so keep low rheological parameters to effectively control the circulating equivalent density (ECD) It is difficult to reconcile the contradiction between the high viscosity and high stick cut to ensure the suspension of barite, which seriously affects the safety of completion work. Therefore, it is particularly important to develop a high-density oil-based completion fluid.

SUMMARY OF THE INVENTION

The present invention proposes a high temperature resistant and high density oil-based well completion fluid and a preparation method thereof to solve the above technical problems.

The present invention proposes a high-density oil-based completion fluid, which is prepared by including the following raw materials in parts by weight: 80-90 parts of white oil, 10-20 parts of calcium chloride aqueous solution, 20-30 parts of main emulsifier, and 10 parts of auxiliary emulsifier ~20 parts, 5-10 parts of organic soil, 5-10 parts of cutting agent, 10-15 parts of wetting agent, 25-30 parts of fluid loss control agent, 5-10 parts of calcium oxide, 150-200 parts of weighting material.

Further, the white oil is 3# white oil.

Further, the concentration of the calcium chloride aqueous solution is 30wt%.

Further, the main emulsifier is a derivative of fatty acid.

Further, the co-emulsifier is an amine derivative of fatty acid acyl.

Further, the cutting agent is an amine derivative of polyamide.

Further, the wetting agent is an amido polyether.

Further, the fluid loss control agent is humic acid amide.

Further, the weighting material is at least one of barite, calcium carbonate or iron ore powder.

The present invention also provides a method for preparing the above-mentioned high-density oil-based completion fluid, comprising the following steps:

(1) place white oil in a mud tank, add main emulsifier and auxiliary emulsifier, and stir to obtain mixture 1;

(2) in above-mentioned mixture one, add calcium chloride aqueous solution, stir, obtain mixture two;

(3) in above-mentioned mixture two, add organic soil, cutting agent, wetting agent, fluid loss reducer, calcium oxide and weighting material, stir, monitor demulsification voltage and reach 400V obtained product.

The present invention has the following advantages:

The product obtained by the invention has good quality stability, the product particle size D50 is less than 1.5 microns, the product temperature resistance can reach more than 240 DEG C, the product density can reach more than 2.5g/cm ³ , and the product can be guaranteed to have good quality for 15-20 days under high temperature conditions. Excellent rheology and suspension stability, do not pollute the formation, and can be reused.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Embodiments of the invention and features of the embodiments may be combined with each other without conflict.

Example 1 A kind of high-density oil-based completion fluid (proportion by mass fraction)

9% 3# white oil, 1% calcium chloride aqueous solution, 2.5% main emulsifier, 3% auxiliary emulsifier, 0.5% organic soil, 0.5% cutting agent, 1% wetting agent, 3% fluid loss reducer, 0.5% %CaO, barite;

Preparation method: including the following steps,

(1) place white oil in a mud tank, add main emulsifier and auxiliary emulsifier, and stir to obtain mixture 1;

(2) in above-mentioned mixture one, add calcium chloride aqueous solution, stir, obtain mixture two;

(3) in above-mentioned mixture two, add organic soil, cutting agent, wetting agent, fluid loss reducer, calcium oxide and weighting material, stir, monitor demulsification voltage and reach 400V obtained product.

Embodiment 2 A kind of high-density oil-based completion fluid (proportion by mass fraction)

8.8% 3# white oil, 1.2% water, 3% main emulsifier, 2% auxiliary emulsifier, 1% organic soil, 0.5% cutting agent, 1% wetting agent, 3% fluid loss reducer, 0.5% CaO, barite

Test Example 1

The GT1 well in Xinjiang Oilfield was completed at a depth of 5920m, and the completion fluid required for oil testing. The completion hydraulic well with a density of 2.43g/cm3 was used. The temperature resistance of the completion fluid was 135°C, and the settlement stability reached 15 days. The completion fluid obtained in Example 1 was tested, and the results are shown in Table 1.

Table 1

The aging conditions are: 200℃×16h; the rheology test temperature is 50℃, and the HTHP filtration loss test temperature is 180℃.

The experimental test density reaches 2.50g/cm3, which satisfies the condition of standing at 135°C for 15 days without hard precipitation of the weighted material, and the sedimentation factor is less than 0.52.

On-site application of 2.43g/cm3 oil-based completion fluid was injected into the wellbore, and it was allowed to stand for 10.5 days to maintain good high-temperature settlement stability and ensure smooth well killing and oil testing.

Test Example 2

Well Bozi 12 is a pre-exploration well located near the structural high point of Bozi No. 12 at the junction of the Bozi Member and the Avat Member in the Keshen Zone of the Kelasu Structural Belt. The designed well depth is 6960m and the actual drilling depth is 7057m. During the drilling of the target layer of Well Bozi 12, the drilling fluid with a relative density of 1.85 has continuous leakage, and the safe drilling fluid density window is small. The pressure gradient (0.37MPa/100m) is predicted to be 6963.5m (-4871.6m above sea level) in the Cretaceous Bashijiqike Formation in Well Bozi 12 (altitude -4871.6m), the formation temperature is about 143.93℃, the formation pressure is about 125.01MPa, and the pressure coefficient is 1.83. The measured formation temperature is 137.7℃. The completion fluid obtained in Example 2 was tested. The results obtained are shown in Table 2.

Table 2

The aging conditions are: 140℃×16h; the rheology test temperature is 50℃, and the HTHP filtration loss test temperature is 140℃.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. within.

Claims (9)

1. The high-temperature-resistant high-density oil-based well completion fluid is characterized by being prepared from the following raw materials, by weight, 80-90 parts of white oil, 10-20 parts of a calcium chloride aqueous solution, 20-30 parts of a main emulsifier, 10-20 parts of an auxiliary emulsifier, 5-10 parts of organic soil, 5-10 parts of a shear improver, 10-15 parts of a wetting agent, 25-30 parts of a fluid loss additive, 5-10 parts of calcium oxide and 150-200 parts of a weighting material.

2. The completion fluid of claim 1, wherein the aqueous calcium chloride solution has a concentration of 30 wt%.

3. The completion fluid of claim 1, wherein the primary emulsifier is a derivative of a fatty acid.

4. The completion fluid of claim 1, wherein the coemulsifier is an amine derivative of a fatty acid.

5. The completion fluid of claim 1, wherein the shear promoter is an amine derivative of a polyamide.

6. The completion fluid of claim 1, wherein the wetting agent is an amido polyether.

7. The completion fluid of claim 1, wherein the fluid loss additive is a humic acid amide.

8. The completion fluid of claim 1, wherein the weighting material is at least one of barite, calcium carbonate, or iron ore fines.

9. A method for preparing the high temperature resistant high density oil-based completion fluid according to any one of claims 1 to 8, comprising the steps of,

(1) putting the white oil into a mud pot, adding a main emulsifier and an auxiliary emulsifier, and stirring to obtain a first mixture;

(2) adding a calcium chloride aqueous solution into the mixture I, and stirring to obtain a mixture II;

(3) and adding organic soil, a cutting agent, a wetting agent, a filtrate reducer, calcium oxide and a weighting material into the mixture II, stirring, and monitoring the demulsification voltage to reach 400V to obtain the product.