CN113372887A - Weak gel tackifier for drilling fluid and preparation method thereof - Google Patents

Abstract

The invention discloses a weak gel tackifier for drilling fluid, which aims to solve the problems that the traditional water-based and oil-based drilling fluids in the prior art cause great damage to reservoirs and can not solve the problems of static sand suspension and dynamic sand carrying of a large-inclination section and a horizontal section. The invention also provides a preparation method of the weak gel tackifier for the drilling fluid, wherein the polysaccharide polymer, sodium carbonate and sodium bicarbonate are firstly mixed to prepare a premix, and other raw materials are mixed. The invention provides a weak gel tackifier for drilling fluid, which takes polysaccharide polymer as a main material and glucoside as an auxiliary material, is favorable for improving the structural viscosity and the shear strength of a solid-free or low-solid-phase drilling fluid system, keeps the weak gel property of the drilling fluid, and improves the carrying and suspending capacity of the drilling fluid. The invention also provides a preparation method of the weak gel tackifier for the drilling fluid, which is simple in process and suitable for large-scale production.

Description

Weak gel tackifier for drilling fluid and preparation method thereof

Technical Field

The invention relates to the technical field of oil and gas exploitation, in particular to a weak gel tackifier for drilling fluid.

Background

With the deep level of the oil and gas exploration and development field and the increasing expansion of the drilling scale, the requirements on the performance of the drilling fluid are continuously increased. For example, in horizontal well drilling, the stability of a well bore is poor, the annular sand suspension and sand carrying capacity of the well bore are poor, the traditional water-based drilling fluid can cause great damage to a reservoir stratum, the problems of static sand suspension and dynamic sand carrying of a large-inclination section and a horizontal section cannot be solved, and a detritus bed is easily formed on the bottom edge of a well bore in the horizontal well drilling construction.

Disclosure of Invention

The invention provides a weak gel tackifier for drilling fluid, which aims to solve the problems that the traditional water-based and oil-based drilling fluids in the prior art cause great damage to a reservoir and static suspended sand and dynamic carried sand of a large-inclination section and a horizontal section cannot be solved.

The invention also provides a preparation method of the weak gel tackifier for the drilling fluid, which is simple in process and suitable for large-scale production.

The technical scheme adopted by the invention is as follows:

a weak gel tackifier for drilling fluid comprises the following raw materials in parts by weight,

30-50 parts of polysaccharide polymer;

20-30 parts of glucoside;

1-2 parts of a dispersing agent;

0.5-1 part of a stabilizer;

1-5 parts of sodium carbonate;

1-5 parts of sodium bicarbonate;

1-5 parts of superfine calcium carbonate;

1-2 parts of a high-temperature resistant stabilizer;

0.5-1 part of deoxidant.

Further, the polysaccharide polymer is one or more of cellulose, chitin, chitosan, xanthan gum, guar gum, hyaluronic acid, alginic acid, modified starch and agar.

Further, the polysaccharide polymer is a mixture of xanthan gum and guar gum, and the mass ratio of the xanthan gum to the guar gum is 1.2-1: 1.

further, the dispersing agent is stearic acid or stearate.

Further, the stabilizer is one or more of polyvinyl alcohol, polyacrylamide and sodium polyacrylate.

Further, the high-temperature resistant stabilizer is sulfonated phenolic resin.

Further, the oxygen scavenger is sodium sulfite or ammonium sulfite.

The preparation method of the weak gel tackifier for the drilling fluid comprises the following steps,

step S1, mixing the polysaccharide polymer, sodium carbonate and sodium bicarbonate to prepare a premix;

step S2, mixing the premix, the dispersing agent, the stabilizing agent, the high-temperature resistant stabilizing agent and the deoxidant in the step S1 with half of the superfine calcium carbonate for 30-60 min;

step S3, adding the rest superfine calcium carbonate, continuously mixing for 5-10 min,

and S4, performing vacuum drying on the mixture mixed in the step S3 at the drying temperature of 20-30 ℃ for 15-20 h to obtain the weak gel tackifier.

Further, in the step S1, the preparation of the premix includes the following steps,

step S11, dissolving a polysaccharide polymer in water under a stirring state to form a polysaccharide polymer solution, wherein the mass concentration is 45-50%, and the dissolving temperature is 50-55 ℃;

step S12, slowly adding sodium carbonate and sodium bicarbonate into the polysaccharide polymer solution under the stirring state, maintaining the temperature at 50-55 ℃, and mixing for 5-10 min to form a premix solution;

step S13, heating the premix solution at a low temperature to evaporate water, wherein the heating temperature is not more than 40 ℃, and when the water content is less than 5%, performing vacuum drying at a drying temperature of 20-30 ℃ until the water content is less than 1% to obtain a premix block material;

and step S14, crushing and grinding the premix block material to obtain premix powder with the particle size of 200-300 meshes.

Further, in the step S1, the preparation of the premix includes the following steps,

step S110, dissolving polysaccharide polymer, mixing with a proper amount of water, and rolling into a dough;

step S120, adding sodium carbonate and sodium bicarbonate, continuing to knead for 1-2 hours, and controlling the temperature of the mixture dough to be 20-30 ℃;

step S130, drawing the kneaded mixture dough into a sheet shape, freezing and drying at low temperature until the moisture content is lower than 1% to obtain premix sheets;

and step S140, crushing and grinding the premix sheet material to obtain premix powder with the particle size of 200-300 meshes.

The invention has the beneficial effects that:

1. the invention provides a weak gel tackifier for drilling fluid, aiming at solving the problems that the traditional water-based and oil-based drilling fluids in the prior art cause great damage to reservoirs and cannot solve the problems of static sand suspension and dynamic sand carrying of large-inclination sections and horizontal sections. The weak gel tackifier comprises polysaccharide polymer, glucoside, dispersant, stabilizer, sodium carbonate, sodium bicarbonate, superfine calcium carbonate, high-temperature resistant stabilizer, oxygen scavenger and the like. Among them, polysaccharide polymers and glucosides are mainly used to increase the viscosity of the drilling fluid system. Sodium carbonate and sodium bicarbonate form a buffer system to regulate the viscosity of the tackifier. The dispersant is adsorbed on the surfaces of polysaccharide polymer and glucoside powder particles by using the amphiphilic group of the dispersant, and is controlled in the dispersing and dissolving processes of the tackifier. The superfine calcium carbonate mainly forms an isolating layer on the surfaces of polysaccharide polymers and glucose powder, and prevents the tackifier from absorbing moisture and agglomerating to influence normal use by utilizing the hydrophobic property of the superfine calcium carbonate. The tackifier disclosed by the invention is beneficial to improving the structural viscosity and the shear force of a solid-free or low-solid-phase drilling fluid system, keeping the weak gel property of the drilling fluid and improving the carrying and suspending capacities of the drilling fluid. Meanwhile, in the drilling fluid formed by matching the tackifier disclosed by the invention, the erosion of the drilling fluid to a well wall is avoided by improving the viscosity of a liquid phase, the well wall is stabilized, the solid phase and the liquid phase of the drilling fluid are prevented from invading a stratum, and a reservoir stratum is protected.

2. The invention also provides a preparation method of the weak gel tackifier for the drilling fluid, and the method is simple in process and suitable for large-scale production.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Examples 1 to 4

The preparation method of the weak gel tackifier for the drilling fluid comprises the following steps,

step S1, mixing the polysaccharide polymer, sodium carbonate and sodium bicarbonate to prepare a premix. Wherein the polysaccharide polymer is one or more of cellulose, chitin, chitosan, xanthan gum, guar gum, hyaluronic acid, alginic acid, modified starch and agar.

In order to improve the homogeneity of the premix, the present embodiment is performed by a similar solution mixing method. Compared with a simple powder mixing mode, the polysaccharide polymer is in closer contact with a buffer system formed by sodium carbonate and sodium bicarbonate, is more beneficial to adjusting the pH value of the system, controlling the extension of molecular chains in the polysaccharide polymer and adjusting the viscosity of the drilling fluid system of the system to form weak gel.

The preparation of the specific premix comprises the following steps,

step S11, dissolving a polysaccharide polymer in water under a stirring state to form a polysaccharide polymer solution, wherein the mass concentration is 45-50%, and the dissolving temperature is 50-55 ℃;

step S12, slowly adding sodium carbonate and sodium bicarbonate into the polysaccharide polymer solution under the stirring state, maintaining the temperature at 50-55 ℃, and mixing for 5-10 min to form a premix solution;

step S13, heating the premix solution at a low temperature to evaporate water, wherein the heating temperature is not more than 40 ℃, and when the water content is less than 5%, performing vacuum drying at a drying temperature of 20-30 ℃ until the water content is less than 1% to obtain a premix block material;

and step S14, crushing and grinding the premix block material to obtain premix powder with the particle size of 200-300 meshes.

And step S2, mixing the premix, the dispersing agent, the stabilizing agent, the high-temperature resistant stabilizing agent and the deoxidant in the step S1 with half of the superfine calcium carbonate for 30-60 min. Wherein the particle size of the superfine calcium carbonate is 500-1000 meshes. The dispersing agent is stearic acid or a stearate such as sodium stearate. The stabilizer is one or more of polyvinyl alcohol, polyacrylamide and sodium polyacrylate. The high temperature resistant stabilizer is sulfonated phenolic resin. The oxygen scavenger is sodium sulfite or ammonium sulfite.

Step S3, adding the rest superfine calcium carbonate, continuously mixing for 5-10 min,

and S4, performing vacuum drying on the mixture mixed in the step S3 at the drying temperature of 20-30 ℃ for 15-20 h to obtain the weak gel tackifier.

Example 1 was carried out according to the above-described method, and the specific raw material compositions are shown in the following table.

TABLE 1 compositions of examples 1-4

In examples 1 to 4, the tackifier was added to the fresh water slurry and the brine slurry of 4% in an amount of 5%, respectively, and the results of the tests were measured according to "Q/9151011466303827X 8", and are shown in the following tables.

TABLE 2 test results of examples 1 to 4

As can be seen from the above results, the tackifier prepared in the examples satisfies the application requirements.

Using the tackifier in the examples as an example, 5% of the additive was added to fresh water slurry, and the rheology of the slurry after hot rolling for 16h at different temperatures was measured, and the results are shown in the following table.

TABLE 3 rheological Properties of drilling fluids after Hot Rolling at different temperatures

Temperature/. degree.C	AV/mPa·s	PV/mPa·s	YP/Pa	(YP/PV)/103S-1	FL/mL
						25	35	10	26	2.6	13
80	31	10	13	1.3	13
						100	25	10	12	1.2	13
120	25	9.5	12	1.3	13
						140	25	9	12	1.3	13

As can be seen from the detection results, the AV and YP/PV of the drilling fluid prepared by the tackifier of the invention are reduced after different hot rolling temperatures. The performance is kept basically stable at 100-140 ℃.

Using the tackifier in the examples as an example, 5% of the tackifier was added to fresh water slurry, and the change of the static shear force after hot rolling at 120 ℃ for 16 hours was shown in the following table.

TABLE 4 static shear force variation

Time/min	Static shear force/Pa
		1	7
5	7
		10	7
30	8
		60	8
120	9
		300	9

According to the detection result, after the drilling fluid prepared by the tackifier disclosed by the invention is subjected to hot rolling, the static shearing force does not change greatly along with time, the sand suspension and carrying of a highly deviated well and a horizontal well are facilitated, and a rock debris bed is prevented from being formed.

In conclusion, the tackifier disclosed by the invention has the following characteristics:

1. has unique rheological property, low apparent viscosity, high dynamic-plastic ratio, high viscosity at low shear rate and no dependence of shear force on time.

2. High dissolving speed, no fish eye, stable performance and simple maintenance.

3. Can quickly form low-permeability mud cakes, effectively reduce the filtration loss of a gap medium, prevent the invasion of foreign fluid, stabilize the well wall and protect a reservoir stratum.

4. The weak gel drilling fluid has good temperature resistance, has good suspended sand carrying capacity at 140 ℃, and can meet the requirement of ultra-deep well drilling construction.

5. The fluorescent light is low, pollution-free and biodegradable, the logging requirements are met, and the discovery and the protection of oil and gas reservoirs are facilitated.

6. The drilling fluid is suitable for drilling vertical wells, inclined wells and horizontal wells, and has more outstanding performance in a solid-free and low-solid-phase drilling fluid system.

Example 5

The preparation method of the weak gel tackifier for the drilling fluid comprises the following steps,

step S1, mixing 35kg of xanthan gum, 1.5kg of sodium carbonate and 2kg of sodium bicarbonate to prepare the premix.

Specifically, the preparation of the premix comprises the following steps,

step S110, dissolving polysaccharide polymer, mixing with a proper amount of water, and rolling into a dough;

step S120, adding sodium carbonate and sodium bicarbonate, continuing to knead for 1-2 hours, and controlling the temperature of the mixture dough to be 20-30 ℃;

step S130, drawing the kneaded mixture dough into a sheet shape, freezing and drying at low temperature until the moisture content is lower than 1% to obtain premix sheets;

and step S140, crushing and grinding the premix sheet material to obtain premix powder with the particle size of 200-300 meshes.

And step S2, mixing the premix obtained in the step S1, 1.5kg of sodium stearate, 0.5kg of sodium polyacrylate, 1kg of sulfonated phenolic resin, 0.5kg of sodium sulfite and 2.5kg of superfine calcium carbonate for 30-60 min. Wherein the particle size of the superfine calcium carbonate is 500-1000 meshes. The dispersing agent is stearic acid or a stearate such as sodium stearate. The stabilizer is one or more of polyvinyl alcohol, polyacrylamide and sodium polyacrylate. The high temperature resistant stabilizer is sulfonated phenolic resin. The oxygen scavenger is sodium sulfite or ammonium sulfite.

Step S3, adding the rest 2.5kg of superfine calcium carbonate, continuously mixing for 5-10 min,

and S4, performing vacuum drying on the mixture mixed in the step S3 at the drying temperature of 20-30 ℃ for 15-20 h to obtain the weak gel tackifier.

In example 5, the tackifier was added to the fresh water slurry and the brine slurry of 4% in an amount of 5%, respectively, and the results of the tests were measured according to "Q/9151011466303827X 8", and are shown in the following table.

Table 5 example 5 test results

As can be seen from the above results, the tackifier prepared in the examples satisfies the application requirements.

Claims (10)

1. The weak gel tackifier for drilling fluid is characterized by comprising the following raw materials in parts by weight,

30-50 parts of polysaccharide polymer;

20-30 parts of glucoside;

1-2 parts of a dispersing agent;

0.5-1 part of a stabilizer;

1-5 parts of sodium carbonate;

1-5 parts of sodium bicarbonate;

1-5 parts of superfine calcium carbonate;

1-2 parts of a high-temperature resistant stabilizer;

0.5-1 part of deoxidant.

2. The weak gel viscosifier for drilling fluids according to claim 1, wherein the polysaccharide polymer is one or more of cellulose, chitin, chitosan, xanthan gum, guar gum, hyaluronic acid, alginic acid, modified starch and agar.

3. The weak gel viscosifier for drilling fluid according to claim 1 or 2, wherein the polysaccharide polymer is a mixture of xanthan gum and guar gum, and the mass ratio of the xanthan gum to the guar gum is 1.2-1: 1.

4. the weak gel viscosifier for drilling fluids according to claim 1, wherein said dispersant is stearic acid or a stearate salt.

5. The weak gel viscosifier for drilling fluids according to claim 1, wherein the stabilizer is one or more of polyvinyl alcohol, polyacrylamide and sodium polyacrylate.

6. The weak gel viscosifier for drilling fluids according to claim 1, wherein said high temperature resistant stabilizer is a sulfonated phenolic resin.

7. The weak gel viscosifier for drilling fluids according to claim 1, wherein said oxygen scavenger is sodium sulfite or ammonium sulfite.

8. A method for preparing the weak gel tackifier for drilling fluid according to any one of claims 1 to 7, comprising the steps of,

step S1, mixing the polysaccharide polymer, sodium carbonate and sodium bicarbonate to prepare a premix;

step S2, mixing the premix, the dispersing agent, the stabilizing agent, the high-temperature resistant stabilizing agent and the deoxidant in the step S1 with half of the superfine calcium carbonate for 30-60 min;

step S3, adding the rest superfine calcium carbonate, continuously mixing for 5-10 min,

and S4, performing vacuum drying on the mixture mixed in the step S3 at the drying temperature of 20-30 ℃ for 15-20 h to obtain the weak gel tackifier.

9. The method for preparing the weak gel viscosifier for drilling fluid of claim 8, wherein the step S1, the preparation of the premix comprises the following steps,

step S11, dissolving a polysaccharide polymer in water under a stirring state to form a polysaccharide polymer solution, wherein the mass concentration is 45-50%, and the dissolving temperature is 50-55 ℃;

step S12, slowly adding sodium carbonate and sodium bicarbonate into the polysaccharide polymer solution under the stirring state, maintaining the temperature at 50-55 ℃, and mixing for 5-10 min to form a premix solution;

step S13, heating the premix solution at a low temperature to evaporate water, wherein the heating temperature is not more than 40 ℃, and when the water content is less than 5%, performing vacuum drying at a drying temperature of 20-30 ℃ until the water content is less than 1% to obtain a premix block material;

and step S14, crushing and grinding the premix block material to obtain premix powder with the particle size of 200-300 meshes.

10. The method for preparing the weak gel viscosifier for drilling fluid of claim 8, wherein the step S1, the preparation of the premix comprises the following steps,

step S110, dissolving polysaccharide polymer, mixing with a proper amount of water, and rolling into a dough;

step S120, adding sodium carbonate and sodium bicarbonate, continuing to knead for 1-2 hours, and controlling the temperature of the mixture dough to be 20-30 ℃;

step S130, drawing the kneaded mixture dough into a sheet shape, freezing and drying at low temperature until the moisture content is lower than 1% to obtain premix sheets;

and step S140, crushing and grinding the premix sheet material to obtain premix powder with the particle size of 200-300 meshes.