CN112538341B - High-temperature-resistant ultrahigh-density oil-based drilling fluid and preparation method thereof - Google Patents
High-temperature-resistant ultrahigh-density oil-based drilling fluid and preparation method thereof Download PDFInfo
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Abstract
The invention provides a high-temperature-resistant ultra-high density oil-based drilling fluid and a preparation method thereof, wherein the high-temperature-resistant ultra-high density oil-based drilling fluid comprises a base fluid and a weight adjusting agent: the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.05-13% of emulsifier, 20-75% of lime, 1-10% of filtrate reducer, 1-10% of bridging agent and 0.05-3% of wetting agent; the weight adjusting agent comprises: calcium chloride aqueous solution and weighting agent; the weighting agent comprises barite, micro manganese ore powder and micro titanium iron ore powder. The oil-based drilling fluid has the characteristics of high temperature resistance, high density, strong stability and excellent rheological property, and can meet the development requirement on ultrahigh-pressure and ultrahigh-temperature stratum.
Description
Technical Field
The invention relates to a high-temperature-resistant ultrahigh-density oil-based drilling fluid and a preparation method thereof, belonging to the technical field of oil exploitation.
Background
The global energy demand promotes the petroleum industry to develop oil and gas resources for extremely severe ultrahigh-pressure and ultrahigh-temperature strata, and the ultrahigh-pressure and ultrahigh-temperature strata are complex, so that the problems of construction difficulty increase and the like can be caused. Based on the problems in drilling construction, it is necessary to research a drilling fluid system suitable for the stratum to ensure the smooth drilling.
At present, the commonly used drilling fluid systems at home and abroad comprise an oil-based drilling fluid system and a water-based drilling fluid system, wherein the oil-based drilling fluid has strong inhibition, is favorable for keeping the well wall stable, and can protect an oil-gas layer, particularly a water-sensitive stratum to the maximum extent; and has strong anti-pollution capability and good lubricity. Meanwhile, the oil-based drilling fluid has stable performance, easy maintenance and good thermal stability. Compared with water-based drilling fluid, the oil-based drilling fluid is more suitable for drilling water-sensitive easily-collapsed complex stratum and can protect a water-sensitive oil-gas layer more effectively, so that the oil-based drilling fluid system gradually develops into the mainstream direction of the drilling fluid system.
In addition, the high-temperature resistant ultrahigh-density drilling fluid is a key factor for determining the success of ultrahigh-pressure ultrahigh-temperature stratum drilling and completion engineering. At present, the ultra-high density oil-based drilling fluid weighted by common barite does not completely meet the field requirement, and theoretical research considers that the weighting limit of the barite is 2.60g/cm 3 About 2.60g/cm 3 The ultra-high density drilling fluid is continuously weighted, and the serious problems of system rheological property deterioration, sedimentation stability damage, system dehydration increase, pollution resistance reduction and the like are faced, so that the safe and efficient development of deeper oil gas is seriously influenced.
Disclosure of Invention
The invention provides a high-temperature-resistant ultrahigh-density oil-based drilling fluid which has high-temperature resistance (about 210 ℃) and high density (2.65 g/cm) 3 ) The high-temperature-resistant and high-pressure-resistant composite material has the characteristics of high stability and excellent rheological property, and can meet the development requirement on ultrahigh-pressure and ultrahigh-temperature stratum.
The invention also provides a preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid, and the preparation method can obtain the high-temperature-resistant (about 210 ℃) high-density (2.65 g/cm) oil-based drilling fluid by controlling the component types, the component proportions and the adding sequence 3 ) The oil-based drilling fluid is high in stability and excellent in rheological property, so that the development requirement on ultrahigh-pressure and ultrahigh-temperature stratum can be met.
The invention provides a high-temperature-resistant ultra-high density oil-based drilling fluid, which comprises a base fluid and a weight adjusting agent:
the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.05-13% of emulsifier, 40-75% of lime, 1-10% of filtrate reducer, 1-10% of bridging agent and 0.05-3% of wetting agent;
the weight adjusting agent comprises: calcium chloride aqueous solution and weighting agent;
the weighting agent comprises barite, micro manganese ore powder and micro titanium iron ore powder.
The high temperature resistant ultra high density oil-based drilling fluid as described above, wherein the emulsifier comprises a polyamide fatty acid and an anionic emulsifier;
the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.0-10% of polyamide fatty acid, 0.05-3% of anionic emulsifier, 40-75% of lime, 1-10% of fluid loss additive, 1-10% of bridging agent and 0.05-3% of wetting agent.
The high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following components in percentage by mass: 17.9% of base oil, 0.07% of tackifier, 0.07% of suspension reinforcing agent, 6.66% of polyamide fatty acid, 0.60% of anionic emulsifier, 50.4% of lime, 6.85% of filtrate reducer, 6.85% of bridging agent and 0.60% of wetting agent.
The high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises barite, micro manganese ore powder and micro titanium iron ore powder in a mass ratio of 3:1:1.
the high-temperature-resistant ultrahigh-density oil-based drilling fluid is characterized in that the mass fraction of the calcium chloride aqueous solution is 25%.
The high temperature resistant ultra-high density oil-based drilling fluid as described above, wherein the suspension enhancer is hydroxyapatite.
The high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the micro-manganese ore powder with the granularity of 0.9-1.3 mu m and the density of 4.68-4.81 g/cm 3 Purity of 90% or more, molar hardness of 5.4 to 5.6, and specific surface area of 4.7m 2 G, abrasionCoefficient of 0.21-0.33, wetting angle of 55 deg. and specific susceptibility of 9X 10 -6 ～15×10 -6 cm 3 (ii) a Curie temperature of about 40 to 60K, and/or,
the granularity of the micro-titanium iron ore powder is 4.7 to 5.3 mu m, and the density is 4.57 to 4.63g/cm 3 Purity of 90% or more, molar hardness of 4.9 to 5.5, and specific surface area of 3.5m 2 G, abrasion coefficient of about 0.29-0.47, wetting angle of about 68-74 DEG, specific susceptibility of 80X 10 -6 ～315×10 -6 cm 3 The Curie temperature is about 80 to 100K.
The high temperature resistant ultra-high density oil-based drilling fluid, wherein the density of the high temperature resistant ultra-high density oil-based drilling fluid is not less than 2.65g/cm 3 。
The invention also provides a preparation method of any one of the high-temperature-resistant ultrahigh-density oil-based drilling fluids, which comprises the following steps:
1) Sequentially adding a tackifier, a suspension reinforcing agent, an emulsifier, lime, a calcium chloride aqueous solution, a filtrate reducer and a bridging agent into base oil to obtain an intermediate system;
2) Adding a weighting agent into the intermediate system to adjust the density to a target density, and adding a wetting agent to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid;
wherein, after each component is added, the mixture is stirred for not less than 5min.
The preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the step of stirring at the speed of 900-1100r/min.
The implementation of the invention has at least the following advantages:
1. the high-temperature-resistant ultrahigh-density oil-based drilling fluid is prepared by compounding the micro manganese mineral powder, the micro titanium iron mineral powder and the barite, so that the rheological property of a system can be effectively improved, the sedimentation stability of the system is improved, the further aggravated tolerance in the case of a complex accident in construction conditions can be kept, and the safe and efficient operation of drilling and completion engineering is ensured;
2. the suspension reinforcing agent adopted by the high-temperature-resistant ultrahigh-density oil-based drilling fluid is beneficial to enhancing the stability of a system under the ultrahigh-temperature ultrahigh-density condition, can ensure that the system keeps better suspension property in the normal drilling and completion use process and in the case of complex site accidents, avoids the settlement of weighting agents and other treating agents, and avoids the adverse effect on drilling and completion tools;
3. the high-temperature-resistant ultra-high density oil-based drilling fluid is preferably a high-temperature-resistant treatment agent, and particularly, the high-temperature-resistant primary emulsifier polyamide fatty acid and the high-temperature-resistant auxiliary emulsifier anionic emulsifier can enhance the stability of a system, improve the demulsification voltage, avoid the settlement of a weighting material and improve the tolerance of the system under the pollution condition;
4. the high-temperature-resistant ultrahigh-density oil-based drilling fluid is stable and does not decompose at a high temperature of 210 ℃, so that the problem of high difficulty in maintaining and treating the drilling fluid caused by high-temperature degradation of a high-molecular polymer can be effectively solved;
5. the high-temperature-resistant ultrahigh-density oil-based drilling fluid has stable flowing property in the environment with high salt content, high calcium content and high solid-phase pollution content, so that the environment with high salt content, high calcium content and high solid-phase pollution content cannot influence the plugging property of the drilling fluid;
6. the preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid is simple in process and mild in condition, does not need assistance of large or complex processing equipment, and therefore can be used for mass production on a construction site, and smooth construction is guaranteed;
7. the preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid has lower raw material cost and processing cost, so that the preparation method can be produced and popularized on a large scale.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on the drawings without inventive labor.
FIG. 1 is a flow chart of a method for preparing the high temperature resistant ultra-high density oil-based drilling fluid of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, 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. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a high-temperature-resistant ultra-high density oil-based drilling fluid, which comprises a base fluid and a weight adjusting agent:
the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.05-13% of emulsifier, 40-75% of lime, 1-10% of filtrate reducer, 1-10% of bridging agent and 0.05-3% of wetting agent;
the weight adjusting agent comprises: calcium chloride aqueous solution and weighting agent;
the weighting agent comprises barite, micro manganese ore powder and micro titanium iron ore powder.
Wherein the adding proportion of the weight regulator is determined according to the target density of the oil-based drilling fluid. During the drilling process, if the real-time density of the oil-based drilling fluid is lower than the target density, a proper amount of weighting agent can be added; if the real-time density of the oil-based drilling fluid is higher than the target density, a proper amount of calcium chloride aqueous solution can be added.
Wherein, the specific mass concentration of the calcium chloride aqueous solution can be 25%.
The oil-based drilling fluid provided by the invention is simple in composition, low in production cost and low in requirements on raw materials, has the characteristics of strong high temperature resistance, high density, good shearing performance and stable system due to special components, and has remarkable anti-collapse performance of inhibiting and plugging, so that the aims of stabilizing the stratum and improving the drilling speed can be fulfilled.
The oil-based drilling fluid is particularly a water-in-oil emulsion drilling fluid.
Wherein, the base oil as the continuous phase of the oil-based drilling fluid is the main component of the oil-based drilling fluid and can be diesel oil, in particular 0# diesel oil.
To maintain the stability of the oil-based drilling fluid at high temperature and high density, a suspension enhancer may be added to the system. The suspension reinforcing agent can ensure that the system keeps better suspension property in the normal well drilling and completion using process and when encountering field complex accidents, avoids the settlement of weighting agents and other treating agents, and avoids causing bad influence on well drilling and completion tools. In particular, the suspension enhancer of the invention may be hydroxyapatite.
The compound of barite, micro manganese ore powder and micro titanium iron ore powder is selected as the weighting agent, and the result shows that the compound weighting agent can effectively adjust the density of the oil-based drilling fluid, so that the rheological property of the system is effectively improved, the settling stability of the system is improved, the further aggravated tolerance in the case of a complex accident in construction conditions can be kept, and the safe and efficient operation of drilling and completion engineering is ensured. And has good adaptability with other components in the system.
In order to further ensure the emulsification of oil and water and avoid the coagulation of the water phase in the oil phase, a wetting agent can be added. The wetting agent is a surfactant with an amphiphilic structure, and can convert the originally hydrophilic solid surface into lipophilicity, so that the mutual solubility ratio of oil and water can be further increased. The wetting agent of the present invention may be specifically selected from sulfonate surfactants.
The viscosity of the oil-based drilling fluid can be adjusted by the tackifier, so that the oil-based drilling fluid can have more suitable viscosity for different formations to be developed, and the current development requirement can be met. The tackifier can be organic bentonite processed by a high-temperature high-pressure wet method, not only can play a role in tackifying, but also has a function of reducing filtration loss to a certain extent, and can increase the emulsification effect of oil and water, so that the stability of the oil-based drilling fluid is enhanced. The organic bentonite processed by the high-temperature high-pressure wet method is obtained by taking bentonite powder as a raw material and sequentially performing dispersion pulping, purification, modification, organic covering, filtration, high-temperature drying and crushing.
In addition to the viscosifying agents described above, which may perform some fluid loss reducing function, fluid loss additives may be added to prevent excessive fluid loss from the oil-based drilling fluid during drilling. In particular, the fluid loss additive of the present invention may be a copolymer of polyvinyl toluene and acrylate that is resistant to high temperatures.
The bridging agent can block the pore entrance of stratum to form very dense filter cake on well wall and to prevent the invasion of filtrate and other pollution source. In particular, the bridging agent of the present invention may be a mixture of calcium carbonates of different particle sizes.
Lime (calcium hydroxide) can react with acidic substances in the stratum, so that the oil-based drilling fluid is prevented from being polluted by the acidic substances.
The high-temperature-resistant ultrahigh-density oil-based drilling fluid disclosed by the invention is composed of the raw materials, and the proportion of each raw material is respectively limited, so that the stable high-temperature-resistant oil-based drilling fluid is favorably formed, the stability of a well wall can be further maintained in the drilling process of an ultrahigh-pressure and ultrahigh-temperature stratum, and the drilling speed is improved. It is worth mentioning that the ratio of weighting agent to aqueous calcium chloride solution is not limited by the present invention, as the actual amount of weighting agent and aqueous calcium chloride solution added can be determined based on the target density of the oil-based drilling fluid. That is, the density of the system is adjusted by adding the weighting agent or the calcium chloride aqueous solution, and when the real-time density of the system meets the requirement, the addition of the weighting agent or the calcium chloride aqueous solution can be stopped.
In order to ensure the stable existence of the water-in-oil emulsified drilling fluid, the emulsifier is an indispensable functional component. The adsorption film with certain strength can be formed on an oil-water interface, and the surface tension of the oil-water interface is reduced, so that the stability of the whole drilling fluid system is maintained. The emulsifier of the invention can be composed of a main emulsifier and an auxiliary emulsifier, wherein the main emulsifier needs to have excellent oleophylic property. In order to ensure the stability of the oil-based drilling fluid at high temperature, a main emulsifier and an auxiliary emulsifier with high-temperature and high-pressure resistance can be selected. The high temperature and high pressure resistance in the invention means that the alloy has excellent stability at 210 ℃ and 150 MPa.
In particular, the primary emulsifier having high temperature resistance may be HPHT polyamide fatty acid, and the secondary emulsifier having high temperature resistance may be an anionic emulsifier. The emulsifier of the composition can not ensure the high-temperature stability of the oil-based drilling fluid, can also improve the demulsification voltage, avoid the settlement of a weighting material and improve the tolerance of the drilling fluid system under the pollution condition.
Further, when the emulsifier comprises the above components, the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.0-10% of polyamide fatty acid, 0.05-3% of anionic emulsifier, 40-75% of lime, 1-10% of fluid loss additive, 1-10% of bridging agent and 0.05-3% of wetting agent.
As an implementation mode, the base fluid comprises the following components in percentage by mass: 27.9% of base oil, 0.07% of tackifier, 0.07% of suspension reinforcing agent, 6.66% of polyamide fatty acid, 0.60% of anionic emulsifier, 50.4% of lime, 6.85% of filtrate reducer, 6.85% of bridging agent and 0.60% of wetting agent.
In addition, the inventors have studied the specific composition of the weighting agent and found that when the mass ratio of barite, micro-manganese ore powder and micro-titanium iron ore powder in the weighting agent is 3:1:1, the weighting agent with different granularities can be effectively graded, so that the stability of a drilling fluid system is improved, the quality of a filter cake is improved, and the water loss capacity of drilling fluid is improved.
Further, when the particle size of the micro manganese ore powder is 0.9-1.3 mu m and the density is 4.68-4.81 g/cm 3 Purity of more than 90%, molar hardness of 5.4-5.6, and specific surface area of 4.7m 2 (g) an abrasion coefficient of 0.21 to 0.33, a wetting angle of 55 DEG and a specific susceptibility of 9X 10 -6 ～15×10 -6 cm 3 (ii) a Curie temperature of 40 to 60K, and/or,
the granularity of the micro-titanium iron ore powder is 4.7 to 5.3 mu m, and the density is 4.57 to 4.63g/cm 3 Purity of 90% or more, molar hardness of 4.9 to 5.5, and specific surface area of 3.5m 2 Per g, abrasion coefficient of 0.29 to 0.47, wetting angle of68-74 DEG, specific susceptibility 80X 10 -6 ～315×10 -6 cm 3 And when the Curie temperature is 80-100K, the oil-based drilling fluid can be ensured to have good high temperature resistance and rheological property under high density, the quality of a filter cake can be obviously improved, and the water loss control capability of a drilling fluid system is optimized.
The oil-based drilling fluid capable of meeting the requirements of high-temperature and high-pressure rheological property, sedimentation stability, high-temperature and high-pressure filtration capacity and pollution resistance of field drilling is obtained by screening and evaluating key properties of various materials by utilizing the compounding principle of the weighting agent. Concretely, the preparation and optimization of an ultrahigh-temperature and ultrahigh-density oil-based drilling fluid system are realized by adopting the grading of micro-manganese and micro-titanium iron ore powder and barite and matching with the use of a high-temperature resistant treatment agent, a complete system formula is formed, and the problem of resisting high-temperature and ultrahigh-density (2.65 g/cm) in the petroleum industry is solved 3 ) The requirements of an oil-based drilling fluid system solve the contradiction between ultrahigh density, temperature resistance, rheological property and dynamic and static sedimentation stability. And aiming at different types of stratums to be developed, the density of the oil-based drilling fluid can be regulated and controlled by controlling the amount of the weighting agent, so that the matching degree with the stratums to be developed is further improved, the drilling speed is effectively improved, the drilling cost is reduced, and the drilling safety is ensured.
The invention also provides a preparation method of any one of the high-temperature-resistant ultrahigh-density oil-based drilling fluids.
Fig. 1 is a flow chart of a preparation method of the high temperature resistant ultra-high density oil-based drilling fluid of the invention, as shown in fig. 1, the preparation method of the invention comprises the following steps:
s101: sequentially adding a tackifier, a suspension reinforcing agent, an emulsifier, lime, a calcium chloride aqueous solution, a filtrate reducer and a bridging agent into base oil to obtain an intermediate system;
wherein, when the emulsifier comprises polyamide fatty acid and anionic emulsifier, the polyamide fatty acid is added firstly, and then the anionic emulsifier is added.
In addition, the addition amount of the calcium chloride aqueous solution can be determined according to the emulsification state of the mixture of the base oil, the tackifier, the suspension enhancer, the emulsifier and the lime, and the mixture after the calcium chloride aqueous solution is added is ensured to be in a uniform state as much as possible.
S102: and adding a weighting agent into the intermediate system to adjust the intermediate system to a target density, and adding a wetting agent to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid.
And after an intermediate system is obtained, adding a weighting agent into the intermediate system until the density of the system reaches the target density, and finally adding a wetting agent to obtain the oil-based drilling fluid.
It should be noted that if the weighting agent is in excess and the density of the system is higher than the target density, the density of the system can be reduced by supplementing the calcium chloride aqueous solution.
In the preparation process of the high-temperature-resistant ultrahigh-density oil-based drilling fluid, after each component is added, the stirring is carried out for not less than 5min.
Preferably, after the tackifier is added into the base oil, stirring is carried out for 5min, then the suspension enhancer is added and stirring is carried out for 5min, then the high-temperature high-pressure modified amide is added and stirring is carried out for 5min, then the anionic emulsifier is added and stirring is carried out for 5min, then the lime is added and stirring is carried out for 5min, then the calcium chloride aqueous solution is added and stirring is carried out for 15min, then the fluid loss additive is added and stirring is carried out for 5min, then the bridging agent is added and stirring is carried out for 5min, then the weighting agent is added and stirring is carried out for adjusting the density (stirring is carried out continuously during the adding process until the target density is reached and then stirring is carried out for 5 min), and finally the wetting agent is added and stirring is carried out for 5min, thus obtaining the high-temperature resistant ultra-high density oil-based drilling fluid of the invention.
The preparation method can adjust the stability of the oil-based drilling fluid to the optimal state, so that the efficiency and the safety of high-temperature and high-pressure stratum development can be ensured.
In addition, the specific addition amounts of all the components in the above preparation method are the same as those described above, and are not described herein again.
Furthermore, the rotating speed of the stirring is 900-1100r/min.
The high temperature resistant ultra-high density oil-based drilling fluid and the preparation method thereof according to the present invention are further described by the following specific examples.
Example 1
The base fluid of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following components in percentage by mass:
base oil (0 # diesel): 27.9 percent
Tackifier (high temperature high pressure wet process organic bentonite): 0.07 percent
Suspension enhancer (hydroxyapatite): 0.07 percent
High temperature resistant primary emulsifier (polyamide fatty acid): 6.66 percent
High temperature resistant co-emulsifier (anionic emulsifier): 0.60 percent
Lime: 50.4 percent
Fluid loss additive (polyvinyl toluene/acrylate copolymer): 6.85 percent
Bridging agent (mixture of calcium carbonate of different particle size): 6.85 percent
Wetting agent (sulfonate surfactant): 0.60 percent
The weight adjusting agent comprises:
the weight-increasing agent comprises 25% of calcium chloride aqueous solution and a weight-increasing agent, wherein the weight-increasing agent comprises barite, micro manganese ore powder and micro titanium iron ore powder in a mass ratio of 3;
the particle size of the micro manganese ore powder is 0.9 to 1.3 mu m, and the density is 4.68 to 4.81g/cm 3 Purity of 90% or more, molar hardness of 5.4 to 5.6, and specific surface area of 4.7m 2 Per g, abrasion coefficient of 0.21-0.33, wetting angle of 55 DEG, specific susceptibility of 9X 10 -6 ～15×10 -6 cm 3 The Curie temperature is 40-60K;
the granularity of the micro-titanium iron ore powder is 4.7 to 5.3 mu m, and the density is 4.57 to 4.63g/cm 3 Purity of 90% or more, molar hardness of 4.9 to 5.5, and specific surface area of 3.5m 2 (g) abrasion coefficient of 0.29-0.47, wetting angle of 68-74 DEG, specific susceptibility of 80X 10 -6 ～315×10 -6 cm 3 The Curie temperature is 80-100K.
The preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following steps:
1) Preparation of the intermediate System
According to the proportion, after adding the tackifier into the base oil, stirring for 5min, adding the suspension enhancer, stirring for 5min, adding the polyamide fatty acid, stirring for 5min, adding the anionic emulsifier, stirring for 5min, adding the lime, stirring for 5min, adding the calcium chloride aqueous solution, stirring for 15min, adding the filtrate reducer, stirring for 5min, adding the bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of high-temperature-resistant ultrahigh-density oil-based drilling fluid
And adding a calcium chloride aqueous solution and a weighting agent into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent, and stirring for 5min to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid No. 1 of the embodiment.
The density of the high-temperature-resistant ultra-high density oil-based drilling fluid is 2.35g/cm 3 。
Example 2
The composition of the high-temperature-resistant ultrahigh-density base liquid in this example is the same as that in example 1, and the addition amounts of the weighting agents (the weighting agent of the calcium chloride aqueous solution and the barite, the micro manganese ore powder and the micro titanic iron ore powder in a mass ratio of 3.
The preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following steps:
1) Preparation of the intermediate System
Adding a tackifier into base oil, stirring for 5min, adding a suspension enhancer, stirring for 5min, adding polyamide fatty acid, stirring for 5min, adding an anionic emulsifier, stirring for 5min, adding lime, stirring for 5min, adding a calcium chloride aqueous solution, stirring for 15min, adding a fluid loss additive, stirring for 5min, adding a bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of high-temperature-resistant ultrahigh-density oil-based drilling fluid
And adding a weighting agent and a calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent, and stirring for 5min to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid No. 2 of the embodiment.
High-temperature-resistant ultrahigh-density oil-based drill of the embodimentThe density of the well fluid is 2.45g/cm 3 。
Example 3
The composition of the base solution in this example was the same as that in example 1, and the amounts of the weighting agents (the weighting agent of the calcium chloride aqueous solution and the barite, the micro manganese ore powder, and the micro titanic iron ore powder at a mass ratio of 3.
The preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following steps:
1) Preparation of the intermediate System
According to the proportion, after adding the tackifier into the base oil, stirring for 5min, adding the suspension enhancer, stirring for 5min, adding the polyamide fatty acid, stirring for 5min, adding the anionic emulsifier, stirring for 5min, adding the lime, stirring for 5min, adding the calcium chloride aqueous solution, stirring for 15min, adding the fluid loss additive, stirring for 5min, adding the bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of high-temperature-resistant ultrahigh-density oil-based drilling fluid
And adding a weighting agent and a calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent, and stirring for 5min to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid No. 3 of the embodiment.
The density of the high-temperature-resistant ultra-high density oil-based drilling fluid is 2.55g/cm 3 。
Example 4
The composition of the base solution in this example was the same as that in example 1, and the amounts of the weighting agents (the weighting agent of the calcium chloride aqueous solution and the barite, the micro manganese ore powder, and the micro titanic iron ore powder at a mass ratio of 3.
The preparation method of the high-temperature-resistant ultrahigh-density oil-based drilling fluid comprises the following steps of:
1) Preparation of the intermediate System
According to the proportion, after adding the tackifier into the base oil, stirring for 5min, adding the suspension enhancer, stirring for 5min, adding the polyamide fatty acid, stirring for 5min, adding the anionic emulsifier, stirring for 5min, adding the lime, stirring for 5min, adding the calcium chloride aqueous solution, stirring for 15min, adding the filtrate reducer, stirring for 5min, adding the bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of high-temperature-resistant ultrahigh-density oil-based drilling fluid
And adding a weighting agent and a calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent, and stirring for 5min to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid No. 4 of the embodiment.
The density of the high-temperature-resistant ultrahigh-density oil-based drilling fluid of the embodiment is 2.65g/cm 3 。
Comparative example 1
The base fluid of the oil-based drilling fluid of the comparative example comprises the following components in percentage by mass:
base oil (0 # diesel): 27.9 percent
Tackifier (high temperature high pressure wet process organic bentonite): 0.07 percent
Suspension enhancer (hydroxyapatite): 0.07 percent
High temperature resistant primary emulsifier (polyamide fatty acid): 6.66 percent
High temperature resistant co-emulsifier (anionic emulsifier): 0.60 percent
Lime: 50.4 percent
Fluid loss additive (polyvinyl toluene/acrylate copolymer): 6.85 percent
Bridging agent (mixture of calcium carbonate of different particle size): 6.85 percent
Wetting agent (sulfonate surfactant): 0.60 percent
The weight adjusting agent comprises:
calcium chloride water solution with mass concentration of 25% and barite;
the preparation method of the oil-based drilling fluid in the comparative example comprises the following steps:
1) Preparation of the intermediate System
According to the proportion, after adding the tackifier into the base oil, stirring for 5min, adding the suspension enhancer, stirring for 5min, adding the polyamide fatty acid, stirring for 5min, adding the anionic emulsifier, stirring for 5min, adding the lime, stirring for 5min, adding the calcium chloride aqueous solution, stirring for 15min, adding the filtrate reducer, stirring for 5min, adding the bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of oil-based drilling fluid
And adding a calcium chloride aqueous solution and the barite into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, and finally adding a wetting agent and stirring for 5min to obtain the oil-based drilling fluid No. 5 of the comparative example.
The density of the oil-based drilling fluid of this comparative example was 2.35g/cm 3 。
Comparative example 2
The composition of the base solution in this comparative example was the same as that in comparative example 1, and the amounts of the weight control agents (calcium chloride aqueous solution and barite) added were different from those in comparative example 1.
The preparation method of the oil-based drilling fluid in the comparative example comprises the following steps:
1) Preparation of the intermediate System
Adding a tackifier into base oil, stirring for 5min, adding a suspension reinforcing agent, stirring for 5min, adding polyamide fatty acid, stirring for 5min, adding an anionic emulsifier, stirring for 5min, adding lime, stirring for 5min, adding a calcium chloride aqueous solution, stirring for 15min, adding a fluid loss additive, stirring for 5min, adding a bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of oil-based drilling fluid
Adding barite and calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent and stirring for 5min to obtain the oil-based drilling fluid No. 6 of the comparative example.
The density of the oil-based drilling fluid of the embodiment is 2.45g/cm 3 。
Comparative example 3
The composition of the base liquid in this comparative example was the same as that in comparative example 1, and the amount of the weight adjusting agent (calcium chloride aqueous solution and barite) added was different from that in comparative example 1.
The preparation method of the oil-based drilling fluid of the comparative example comprises the following steps:
1) Preparation of the intermediate System
Adding a tackifier into base oil, stirring for 5min, adding a suspension reinforcing agent, stirring for 5min, adding polyamide fatty acid, stirring for 5min, adding an anionic emulsifier, stirring for 5min, adding lime, stirring for 5min, adding a calcium chloride aqueous solution, stirring for 15min, adding a fluid loss additive, stirring for 5min, adding a bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of oil-based drilling fluid
And adding barite and calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the density reaches the target density, then stirring for 5min, finally adding a wetting agent, and stirring for 5min to obtain the oil-based drilling fluid 7# of the comparative example.
The density of the oil-based drilling fluid of this example was 2.55g/cm 3 。
Comparative example 4
The composition of the base solution in this comparative example was the same as that in comparative example 1, and the amounts of the weight control agents (calcium chloride aqueous solution and barite) added were different from those in comparative example 1.
The preparation method of the oil-based drilling fluid of the comparative example comprises the following steps:
1) Preparation of the intermediate System
Adding a tackifier into base oil, stirring for 5min, adding a suspension enhancer, stirring for 5min, adding polyamide fatty acid, stirring for 5min, adding an anionic emulsifier, stirring for 5min, adding lime, stirring for 5min, adding a calcium chloride aqueous solution, stirring for 15min, adding a fluid loss additive, stirring for 5min, adding a bridging agent, and stirring for 5min to obtain an intermediate system;
2) Preparation of oil-based drilling fluid
Adding barite and calcium chloride aqueous solution into the intermediate system to adjust the density, continuously stirring in the adding process until the target density is reached, then stirring for 5min, finally adding a wetting agent and stirring for 5min to obtain the oil-based drilling fluid 8# of the comparative example.
The density of the oil-based drilling fluid of the embodiment is 2.65g/cm 3 。
Test example 1
The oil-based drilling fluids 1 to 4# and the comparative examples 5 to 8# of the above examples are subjected to aging treatment, wherein the aging treatment comprises hot rolling for 16h in an incubator at 210 ℃, and the rheological properties (including apparent viscosity AV, plastic viscosity PV, dynamic shear force YP and rotational viscosity) of the drilling fluids 1 to 8# before and after aging are measured according to the GB/T16783.2 standard
Static shear Gel), the breaking voltage Es was measured according to API recommended Practice (API recommended Practice) 13B-2, third edition (1998, 2 months), and the results are shown in table 1.
TABLE 1
The test conditions in table 1 are: the oil-water ratio is 90:10
As can be seen from Table 1:1. the oil-based drilling fluid disclosed by the embodiment of the invention is stable in performance, the performance basically keeps stable after the oil-based drilling fluid is aged for 16 hours at 210 ℃, obvious deterioration or deterioration is avoided, and the performance of a drilling fluid system is better.
2. The apparent viscosity, the plastic viscosity, the fluid rheological property, the yield value and other data of the oil-based drilling fluid disclosed by the embodiment of the invention are superior to those of the oil-based drilling fluid in the comparative example, so that the oil-based drilling fluid disclosed by the embodiment of the invention can still show excellent rheological property under high density.
Test example 2
The oil-based drilling fluid 4# is hot-rolled for 16h at 150 ℃, 180 ℃ and 210 ℃ respectively, then taken out, and the rheological properties (including apparent viscosity AV, plastic viscosity PV, dynamic shear force YP, rotational viscosity (phi 6/phi 3), static shear force Gel and demulsification voltage Es) of the drilling fluid 4# before and after hot rolling at various temperatures are measured according to the same method as the test example 1, and the test results are shown in Table 2.
TABLE 2
The test conditions in table 2 were: oil-water ratio of 90:10
As can be seen from Table 2: after the oil-based drilling fluid disclosed by the embodiment of the invention is subjected to high-temperature hot rolling, the rheological property of the oil-based drilling fluid is not changed greatly, so that the temperature resistance of the oil-based drilling fluid disclosed by the embodiment of the invention can meet the drilling requirement of a high-temperature and high-pressure stratum.
Test example 3
The oil-based drilling fluid 4# is divided into four groups, calcium sulfate with the mass of 5% of that of the oil-based drilling fluid is added into the first group of oil-based drilling fluid, sodium chloride with the mass of 5% of that of the oil-based drilling fluid is added into the second group of oil-based drilling fluid, drill cuttings with the mass of 5% of that of the oil-based drilling fluid are added into the third group of oil-based drilling fluid, and the unadditized oil-based drilling fluid is used as the fourth group, and the rheological properties (including apparent viscosity AV, plastic viscosity PV, dynamic shear force YP, rotational viscosity (phi 6/phi 3), static shear force Gel and demulsification voltage Es) of the four groups of drilling fluids before and after hot rolling for 16h in a constant temperature box at 210 ℃ are measured according to the method of test example 1, and the test results are shown in Table 3.
TABLE 3
The test conditions in table 3 were: oil-water ratio of 90:10
As can be seen from Table 3: when the oil-based drilling fluid disclosed by the embodiment of the invention encounters a large-section salt-gypsum layer and soft mudstone, the flowing property of the drilling fluid fluctuates to a certain extent, but the drilling is not influenced, so that the oil-based drilling fluid still has good plugging and anti-collapse properties in high-salt, high-calcium and high-solid environments.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. The high-temperature-resistant ultra-high density oil-based drilling fluid is characterized by comprising a base fluid and a weight adjusting agent:
the base fluid comprises the following components in percentage by mass: 15-35% of base oil, 0.05-1.50% of tackifier, 0.05-1.50% of suspension enhancer, 1.0-10% of polyamide fatty acid, 0.05-3% of anionic emulsifier, 40-75% of lime, 1-10% of fluid loss additive, 1-10% of bridging agent and 0.05-3% of wetting agent;
the weight adjusting agent comprises: calcium chloride aqueous solution and weighting agent; the mass fraction of the calcium chloride aqueous solution is 25%;
the weighting agent comprises barite, micro manganese ore powder and micro titanium iron ore powder; the mass ratio of the barite to the micro manganese ore powder to the micro titanium iron ore powder is (3);
the suspension reinforcing agent is hydroxyapatite.
2. The high temperature resistant ultra-high density oil-based drilling fluid of claim 1, wherein the base fluid comprises the following components in percentage by mass: 27.9 percent of base oil, 0.07 percent of tackifier, 0.07 percent of suspension reinforcing agent, 6.66 percent of polyamide fatty acid, 0.60 percent of anionic emulsifier, 50.4 percent of lime, 6.85 percent of fluid loss additive, 6.85 percent of bridging agent and 0.60 percent of wetting agent.
3. The high temperature resistant ultra-high density oil-based drilling fluid of claim 1, wherein the micro manganese ore powder has a particle size of 0.9 to 1.3 μm and a density of 4.68 to 4.81g/cm 3 Purity of 90% or more, molar hardness of 5.4 to 5.6, and specific surface area of 4.7m 2 (g) an abrasion coefficient of 0.21 to 0.33, a wetting angle of 55 DEG and a specific susceptibility of 9X 10 -6 ～15×10 -6 cm 3 (iv) g, curie temperatureIs 40 to 60K, and/or,
the granularity of the micro-titanium iron ore powder is 4.7 to 5.3 mu m, and the density is 4.57 to 4.63g/cm 3 Purity of 90% or more, molar hardness of 4.9 to 5.5, and specific surface area of 3.5m 2 G, abrasion coefficient of 0.29-0.47, wetting angle of 68-74 deg, specific susceptibility of 80X 10 -6 ～315×10 -6 cm 3 The Curie temperature is 80-100K.
4. The high temperature resistant ultra high density oil-based drilling fluid of claim 1, wherein the density of the high temperature resistant ultra high density oil-based drilling fluid is not less than 2.65g/cm 3 。
5. The method for preparing the high temperature resistant ultra-high density oil-based drilling fluid of any one of claims 1 to 4, comprising the steps of:
1) Sequentially adding a tackifier, a suspension reinforcing agent, polyamide fatty acid, an anionic emulsifier, lime, a calcium chloride aqueous solution, a filtrate reducer and a bridging agent into base oil to obtain an intermediate system;
2) Adding a weighting agent into the intermediate system to adjust the density to a target density, and adding a wetting agent to obtain the high-temperature-resistant ultrahigh-density oil-based drilling fluid;
wherein, after each component is added, the mixture is stirred for not less than 5min.
6. The method of preparing a high temperature resistant ultra high density oil-based drilling fluid of claim 5, wherein the rate of agitation is 900-1100r/min.
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