CN101864285B - Deepwater cementing low-temperature early strength agent - Google Patents

Abstract

The invention relates to a low-temperature early-strength agent for deep-water well cementing. Each component and content of the low-temperature early-strength agent are as follows: alkali metal bromide: 33-66% by weight; sodium metaaluminate: 6-16% by weight; alkali metal hydroxide Compounds: 15 to 35% by weight; Silicon dioxide: 8 to 15% by weight; Alcohol amines: 0.8 to 1.5% by weight. The alkali metal bromide is one, two or more mixtures of NaBr, KBr and LiBr; the alkali metal hydroxide is NaOH, KOH or a mixture thereof; the alcohol amine organic compound is triethanolamine, Triisopropanolamine or mixtures thereof. The present invention has little effect on the rheology of cement slurry under low temperature conditions, can promote rapid solidification of cement slurry under low temperature conditions, and achieve higher early strength, shorten the thickening time of cement slurry under low temperature conditions, and can well meet the requirements of Surface casing cementing construction requirements under low temperature, shallow gas and other conditions.

Description

Low temperature early strength agent for deep water well cementing

Technical field

The invention relates to a low-temperature early-strength agent for deep-water well cementing, and belongs to the technical field of oil-gas well cementing.

Background technique

The exploration and development of oil and gas resources in deep water areas is limited by the harsh and complex environment and storage characteristics, and has the characteristics of "four highs", namely high-tech, high-risk, high-skilled personnel, and high return. Whether a well can be safely and economically exploited for decades, and whether it can withstand the test of stimulation measures, perforation, exploitation and various workover operations in the production process of oil and gas wells, is often related to the cementing process. Quality is closely related. For the difficulties faced by deep water exploration, the quality requirements for deep water cementing are often particularly high. Compared with conventional cementing, deepwater cementing, especially in the surface section, often faces unfavorable factors such as low temperature, soft formation, and shallow water flow.

At present, the water-soluble early-strength agents of deep-water cementing slurry are mainly chlorides, which have side effects such as large hydration heat release and corrosion of casing and cement; non-water-soluble early-strength agents can only be used for dry mixing. The well site of the equipment has certain application limitations, and is sensitive to temperature, so it can only be applied to a single temperature condition.

Therefore, the development of a new type of low-temperature early strength agent to prevent annular channeling and improve cementing quality will not only provide necessary technical support for domestic deep-water oil and gas wells, but also for shallow gas and other cementing conditions. , which is of great significance in the development of low temperature oil and gas reservoirs.

Contents of the invention

The object of the present invention is to provide a low-temperature early-strength agent for deep-water well cementing, which can shorten the thickening time of cement slurry under low-temperature conditions, improve the early-stage compressive strength of cement stone, and can be used in cementing oil and gas reservoirs under low-temperature conditions , especially suitable for ocean deep water cementing under low temperature conditions.

In order to achieve the above technical objectives, the present invention provides the following technical solutions.

Low temperature early strength agent for deep water well cementing, each component and its content are as follows:

Alkali metal bromide: 33-66% by weight;

Sodium metaaluminate: 6-16% by weight;

Alkali metal hydroxide: 15-35% by weight;

Silicon dioxide: 8 to 15% by weight;

Organic alcohol amines: 0.8 to 1.5% by weight.

The alkali metal bromide is one, two or a mixture of two or more of NaBr, KBr and LiBr; the alkali metal hydroxide is NaOH, KOH or a mixture thereof; and the silicon dioxide is nano-scale.

The alcohol amine organic substance is triethanolamine, triisopropanolamine or a mixture thereof.

All the above substances are commercially available.

The preparation method of the low-temperature early strength agent composition of the present invention is as follows: weigh the alkali metal bromide, sodium metaaluminate, alkali metal hydroxide, silicon dioxide and alcohol amine organic matter according to the above ratio; Mix evenly in the machine.

The alkali metal bromide and alcohol amine organic matter in the invention can chemically react with cement colloidal minerals to form complexes, which accelerates the cement hydration process and promotes the development of early strength of cement stone. Take alcohol amine organic compounds as an example, which contain unshared electron pairs, so it is easy to form complex ions with other ions, especially some metal ions, through coordinate bonds, so it is a good complexing agent. In alkaline solution, it is easy to form water-soluble coordination compounds with Al ³⁺ and Fe ³⁺ ions in the hydration products on the surface of cement particles. Therefore, the formation of soluble points on the surface of cement particles accelerates the C in grade G cement. ₃ A, C ₂ A and C ₄ AF dissolve faster, and the reaction with gypsum is accelerated accordingly, and the amount of calcium sulfoaluminate (calcium vanadium AFT) is increased, so that the volume expansion will be basically completed before the cement slurry hardens , so it can improve the compactness and compressive strength of cement stone, especially the early strength. In addition, the addition of the alkali metal hydroxide in the present invention increases the _metastable supersaturation of Ca(OH) in the liquid phase, which will more effectively prevent the tendency of _C3A to form loose crystals in the early stage of hydration, thereby improving the cementitiousness. density and strength. Sodium metaaluminate among the present invention, its main component is metaaluminate, and its main function is to provide effective component and strengthen the alkalinity of solution for the formation of calcium vanadite AFt with lime, simultaneously, they add water The initial exothermic reaction increases the liquid phase temperature, which is beneficial to promote the formation of hydration products and the development of slurry strength. The main function of the silica in the present invention is to fill the gaps between the cement particles, thereby improving the compactness of the cement stone.

Compared with the prior art, the low-temperature early strength agent of the present invention has the following beneficial effects: (1) It has little influence on the rheology of cement slurry under low-temperature conditions. (2) Promote the rapid solidification of cement slurry under low temperature conditions and achieve high early strength. (3) Shorten the thickening time of cement slurry under low temperature conditions. Therefore, it can well meet the construction requirements of surface casing cementing under the conditions of low temperature and shallow gas.

Description of drawings

Fig. 1 is the thickening curve of cement slurry prepared under the conditions of 30°C and 20MPa by adding 3% by weight of the low-temperature early strength accelerator of the present invention to Jiahua G-grade oil well cement with a water-cement ratio of 0.44.

Fig. 2 is the development curve of the compressive strength of the prepared cement slurry at 30°C and 14MPa by adding 3% by weight of the low-temperature early strength accelerator of the present invention to Jiahua G-grade oil well cement with a water-cement ratio of 0.44.

Detailed ways

In the embodiments of the present invention, unless otherwise specified, the percentages are all percentages by weight.

Example 1:

Weigh 35% Potassium Bromide, 15% Sodium Metaaluminate, 35% Potassium Hydroxide, 14% Silicon Dioxide, 1% Alcoholamine organic matter according to the above ratio; weigh Potassium Bromide, Sodium Metaaluminate , Potassium Hydroxide, Silicon Dioxide, and Alcoholamines are sequentially added into the mixer and mixed evenly to obtain the low-temperature early-strength agent "ZQ-1" of the present invention.

Example 2:

Weigh 30% sodium bromide, 30% potassium bromide, 7% sodium metaaluminate, 24% sodium hydroxide, 8% silicon dioxide, 1% alcohol amine organic matter according to the above ratio; Sodium, potassium bromide, sodium metaaluminate, sodium hydroxide, silicon dioxide, and alcohol amine organic substances are sequentially added into the mixer and mixed evenly to obtain the low-temperature early strength agent "ZQ-2" of the present invention.

Example 3:

Weigh 53% sodium bromide, 12% sodium metaaluminate, 15% sodium hydroxide, 9.2% silicon dioxide, 0.8% alcohol amine organic matter according to the above ratio; weigh the sodium bromide, sodium metaaluminate , Sodium Hydroxide, Silicon Dioxide, and Alcoholamines are sequentially added into the mixer and mixed evenly to obtain the low-temperature early-strength agent "ZQ-3" of the present invention.

Example 4: Early-strength function of low-temperature early-strength agent "ZQ-2"

Jiahua G-grade oil well cement was used in the experiment, and pure cement slurry with a water-cement ratio of 0.44 was used. The compressive strength test was carried out by curing in a low-temperature water bath under normal pressure. Table 1 shows the influence of low-temperature early strength agent on the compressive strength of Jiahua G-grade cement under the conditions of different dosage, different temperature and different curing time.

It can be seen from the results that under the condition of normal pressure and low temperature, the low temperature early strength agent has a significant early strengthening effect on the conventional density pure cement slurry, and the lower the temperature and the shorter the curing time, the higher the degree of increase in the compressive strength of cement stone.

Table 1 Effect of early strength agent on the compressive strength of cement stone

Example 5: Effect of low temperature early strength agent "ZQ-2" on the thickening performance of cement slurry

Jiahua G-grade oil well cement was used in the experiment, and pure cement slurry with a water-cement ratio of 0.44 was used. The thickening time of cement slurry at different temperatures was determined. The results are shown in Table 2. It can be seen from the table that the low-temperature strengthening agent in the present invention can significantly shorten the thickening time of cement slurry under low temperature conditions, and the thickening "transition time" of cement slurry is also significantly shortened, showing a certain "near right-angle thickening" Features, good channeling resistance.

Table 2 Effect of early strength agent on the thickening performance of cement slurry

Example 6: Effect of low temperature early strength agent "ZQ-2" on the performance of common cement slurry systems

As a new oil well cement admixture, the low-temperature early-strength agent in the present invention must not only meet low-temperature early-strength characteristics, but also have good compatibility with other commonly used oil well cement admixtures in order to be successfully popularized in oil and gas well cementing operations. sex.

In order to test the adaptability of the medium and low temperature early strength agent of the present invention, its influence on the comprehensive performance of various commonly used cement slurry systems was analyzed experimentally. Table 3 and Table 4 respectively show the influence of low temperature early strength agent "ZQ-2" on the performance of LT-1A cement slurry system and JS-2 cement slurry system, including water loss, free water, thickening time and compressive strength and other performance. Among them, the curing conditions of the compressive strength experiment: curing in a normal pressure water bath; the experimental pressure of the thickening time is 7-15MPa.

Table 3 The effect of early strength agent on the main properties of LT-1A cement slurry system

Table 4 Effect of early strength agent on main properties of JS-2 cement slurry system

As can be seen from the analysis in the table, the low-temperature early-strength agent in the present invention has a significant early strengthening effect on these cement slurry systems, and the comprehensive performance coordination of the system is good, and the thickening time is easy to control, and has a great impact on stability, rheology and No adverse effects such as dehydration. This research experiment also investigated the early strengthening effect and other engineering properties of this low-temperature early strength agent on other commonly used cement slurry systems (including LT-2 cement slurry system, HS-2A cement slurry system and latex LATEX2000 cement slurry system, etc.) the impact of the situation. Experimental results show that the low-temperature accelerator of the present invention has good compatibility with the admixtures of these cement slurry systems.

Example 7: Thickening performance and compressive strength analysis of low temperature early strength agent "ZQ-2"

Figure 1 is the thickening curve of the cement slurry prepared by adding 3% "ZQ-2" low-temperature early strength accelerator to Jiahua G grade oil well cement at a water-cement ratio of 0.44 at 30°C and 20MPa. It can be clearly seen that the thickening time is 150 minutes, and the thickening transition time is 13 minutes. The curve is "near right angle thickening", indicating that the system has good channeling resistance.

Figure 2 shows the development of the compressive strength of the cement slurry prepared by adding 3% "ZQ-2" low-temperature early-strength agent to Jiahua G-grade oil well cement at a water-cement ratio of 0.44 at 30°C and 14MPa. From the graph analysis, it can be concluded that when "ZQ-2" low-temperature early strength agent is added to the G-grade cement raw slurry, the compressive strength of the system will be as high as 0.842MPa in 6 hours, which is higher than that of the G-grade raw slurry under the same conditions. up 239.52%. It can be confirmed that: ZQ-A low-temperature early-strength agent has good early-strength effect on G-grade oil well cement.

Claims (3)

1. Deep water cementing low temperature early strength agent, each component and its content are as follows: Alkali metal bromide: 33-66% by weight; Sodium metaaluminate: 6-16% by weight; Alkali metal hydroxide: 15-35% by weight; Silicon dioxide: 8 to 15% by weight; Alcohol amine organic matter: 0.8 to 1.5% by weight; The alkali metal bromide is one, two or more mixtures of NaBr, KBr and LiBr, the alkali metal hydroxide is NaOH, KOH or a mixture thereof, and the alcohol amine organic compound is triethanolamine, Triisopropanolamine or mixtures thereof. 2. The low-temperature early-strength agent according to claim 1, wherein its components and proportions are as follows: 35% by weight of potassium bromide, 15% by weight of sodium metaaluminate, 35% by weight of potassium hydroxide, silicon dioxide 14% by weight, triethanolamine or triisopropanolamine 1% by weight. 3. The low-temperature early-strength agent according to claim 1, wherein its components and ratios are as follows: 30% by weight of sodium bromide, 30% by weight of potassium bromide, 7% by weight of sodium metaaluminate, sodium hydroxide 24% by weight, silicon dioxide 8% by weight, triethanolamine or triisopropanolamine 1% by weight.

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