Low-temperature drilling fluid for drilling in plateau extremely cold environment and preparation method thereof

Abstract

The invention relates to a low-temperature drilling fluid for drilling in a plateau extremely cold environment and a preparation method of the low-temperature drilling fluid. The existing drilling fluid cannot meet the plateau low-temperature severe environment in the aspects of low-temperature resistance and specific heat capacity at the same time. The low-temperature drilling fluid for drilling in the plateau extremely cold environment is prepared from the following components in percentage by mass: 3-5% of a slurry making material; 10%-16% of an anti-freezing agent; 0.1% of an inorganic modification treatment agent; 1.5% of a filtrate reducer; 0.2% of a friendly polymer treating agent; and the balance of water. Appropriate modification components such as the anti-freezing agent, the inorganic modification treatment agent and the filtrate reducer are selected to serve as a formula of the low-temperature-resistant drilling fluid suitable for plateau drilling construction, the low-temperature-resistant drilling fluid can effectively cope with severe cold and severe conditions of plateau, and the low-temperature-resistant drilling fluid has certain specific heat capacity and good rheological property and inhibition capacity while having the low-temperature-resistant characteristic; the strict environmental protection requirements of the plateau are met.

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid, and in particular to a low-temperature drilling fluid for drilling in an extremely cold plateau environment and a preparation method thereof. Background Art

[0002] The plateau has a complex ecological environment, changeable geological conditions, and a cold climate, which poses a huge obstacle to drilling work. The permafrost in the plateau mountainous areas is distributed irregularly and unevenly, and covers a large amount of sensitive vegetation. In addition, the distribution of hard and soft rocks is complex, and cracks have developed in the steep slope sandstone, resulting in malignant leakage. These complex conditions often cause drilling fluid leakage and borehole shrinkage during drilling, and even cause well accidents such as drill stuck and drill buried.

[0003] In order to ensure the normal drilling in the high-cold plateau, as the temperature decreases, the basic mechanical properties of the drilling fluid must be guaranteed as follows: (1) The drilling fluid can overcome the condensation tendency in a low-temperature environment. (2) Under low-temperature conditions, the viscosity of the drilling fluid will not decrease significantly, and the rheological properties will remain stable, which will not affect the drilling fluid's function of cleaning the drill bit and the efficiency of carrying cuttings. (3) The heat generated by the friction between the drill bit and the formation will be transmitted to the hole wall through the drilling fluid. The drilling fluid with too high a temperature will cause the rock formation on the hole wall to produce too large a temperature difference between hot and cold, resulting in collapse, leading to borehole collapse and other accidents. In order to ensure the normal drilling of the plateau formation, the drilling fluid must have a certain low-temperature resistance and a certain specific heat capacity to ensure that the temperature change in the hole is effectively controlled, thereby ensuring the safe drilling. At present, there are few low-temperature drilling fluids that have excellent performance in both low-temperature resistance and specific heat capacity. Summary of the invention

[0004] The purpose of the present invention is to provide a low-temperature drilling fluid for drilling in an extremely cold plateau environment and a preparation method thereof, while improving the low-temperature resistance and specific heat capacity of the low-temperature drilling fluid, ensuring that the low-temperature drilling fluid has good rheological properties and inhibition ability under low-temperature conditions.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] Low-temperature drilling fluid for drilling in an extremely cold plateau environment, the low-temperature drilling fluid is prepared from the following components in mass percentage:

[0007] Pulping materials 3%-5%;

[0008] Antifreeze 10%-16%;

[0009] Inorganic modification agent 0.1%;

[0010] Fluid loss reducer 1.5%;

[0011] Friendly polymer treatment agent 0.2%;

[0012] The balance is water.

[0013] Furthermore, the slurry-making material is sodium clay.

[0014] Furthermore, the antifreeze agent is sodium formate.

[0015] Furthermore, the inorganic modification agent is sodium silicate.

[0016] Furthermore, the fluid loss reducer is carboxymethyl starch.

[0017] Furthermore, the friendly polymer treatment agent is gum arabic.

[0018] Further, the low-temperature drilling fluid is prepared from the following components in percentage by mass: 3% of slurry material;

[0019] Antifreeze 10%;

[0020] Inorganic modification agent 0.1%;

[0021] Fluid loss reducer 1.5%;

[0022] Friendly polymer treatment agent 0.2%;

[0023] The balance is water.

[0024] Further, the low-temperature drilling fluid is prepared from the following components in percentage by mass: 5% of slurry material;

[0025] Antifreeze 12%;

[0026] Inorganic modification agent 0.1%;

[0027] Fluid loss reducer 1.5%;

[0028] Friendly polymer treatment agent 0.2%;

[0029] The balance is water.

[0030] Further, the low-temperature drilling fluid is prepared from the following components in percentage by mass: 5% of slurry material;

[0031] Antifreeze 16%;

[0032] Inorganic modification agent 0.1%;

[0033] Fluid loss reducer 1.5%;

[0034] Friendly polymer treatment agent 0.2%;

[0035] The balance is water.

[0036] On the other hand, a method for preparing the low-temperature drilling fluid for drilling in an extremely cold plateau environment is provided, the method comprising:

[0037] Add slurry materials to the water in a stirring state, stir and cure;

[0038] Add friendly polymer treatment agent and fluid loss reducer under stirring;

[0039] Then continue stirring and add antifreeze;

[0040] After continuing to stir, the inorganic modifying agent is added, and after stirring and curing, the low-temperature drilling fluid is obtained.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention provides a low-temperature drilling fluid for drilling in an extremely cold plateau environment and a preparation method thereof. Suitable antifreeze agents, inorganic modification treatment agents, filtrate reducers and other modification components are selected as a low-temperature resistant drilling fluid formula suitable for plateau drilling construction. The low-temperature resistant drilling fluid effectively copes with the severe cold conditions of the plateau. While having low-temperature resistance, it has a certain specific heat capacity, good rheological properties and inhibition ability, and meets the strict environmental protection requirements of the plateau. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below. The preferred embodiments of the present invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0044] In the description of this patent, it is necessary to understand that all the technical and scientific terms used have the same meanings as those generally understood by ordinary technicians in the field to which this patent belongs. When there is a contradiction, the definitions in this specification shall prevail. If not otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, the reagents used in the examples are commercially available products, and the devices used in the examples are existing devices. The limitation of means, reagents or devices cannot be understood as a limitation of this patent, and the same type of means, reagents or devices for solving the same technical problems are within the scope of protection of this patent.

[0045] In the description of this patent, it is to be understood that when an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0046] In the description of this patent, it should be understood that multiple steps are involved in the description of the method, which should not be understood as a limitation on the order of the method steps. When solving the same technical problem, the technical solution obtained only by changing the order of the steps is also within the scope of protection of this patent.

[0047] The low-temperature resistant media currently used in different drilling fluids are different. Ethanol, methanol, ethylene glycol, etc. are often used in hydrophilic drilling fluids, while butyl acetate, kerosene, DFA, etc. are often used in hydrophobic drilling fluids. Based on the needs of on-site drilling work, in order to protect the plateau ecological environment, the low-temperature resistant medium needs to have safe and pollution-free characteristics. The high permeability of kerosene causes drilling fluids to often leak, causing great pollution to the plateau ecological environment. From the drilling perspective, the solid content has a great influence on the plastic viscosity of the fluid. Therefore, the plastic viscosity of the brine system is lower than that of the traditional fluid system, which will reduce the pressure loss downhole and help to improve the drilling efficiency. In general, inorganic electrolytes and organic alcohols have low freezing points and good low-temperature adaptability, but from the perspective of economic adaptability, the present invention chooses to use halide salts and formates as antifreeze.

[0048] Specifically, the present invention provides a low-temperature drilling fluid for drilling in an extremely cold plateau environment, which is used for engineering geological coring exploration and is prepared from the following components in mass percentage:

[0049] Pulping materials 3%-5%;

[0050] Antifreeze 10%-16%;

[0051] Inorganic modification agent 0.1%;

[0052] Fluid loss reducer 1.5%;

[0053] Friendly polymer treatment agent 0.2%;

[0054] The balance is water.

[0055] In the above recipe:

[0056] The slurry making material is sodium clay, which is natural sodium bentonite after hydration for 24 hours.

[0057] The antifreeze agent is sodium formate, which has a good effect on lowering the freezing point. The drilling fluid system prepared with sodium formate has semi-permeability, can achieve high density, low viscosity, increase drilling speed, strong inhibition, and good water loss.

[0058] The inorganic modification agent is sodium silicate, which has good viscosity and stickiness, is conducive to improving rheology and the bearing capacity of drilling fluid, and can effectively inhibit hydration expansion and resist collapse. In addition, compared with soda ash and caustic soda, sodium silicate is powdery, less corrosive and easy to transport.

[0059] The fluid loss reducer is carboxymethyl starch, which is a stabilizer and water retaining agent in the mud, and plays the role of reducing water loss and agglomeration stability of clay particles in the drilling fluid.

[0060] The friendly polymer treating agent is gum arabic, which is used to adjust the viscosity and rheological properties of the drilling fluid.

[0061] The method for preparing the low-temperature drilling fluid for drilling in an extremely cold plateau environment specifically comprises the following steps:

[0062] S1: Add slurry materials into the water under stirring, stir and cure;

[0063] S2: Add friendly polymer treatment agent and fluid loss reducer under stirring;

[0064] S3: After that, continue stirring and add antifreeze;

[0065] S4: After continuing stirring, the inorganic modifying agent is added, and after stirring and curing, the low-temperature drilling fluid is obtained.

[0066] Embodiment 1:

[0067] The low-temperature drilling fluid of the present invention is prepared from the following components in percentage by mass:

[0068] Pulping materials 3%;

[0069] Antifreeze 10%;

[0070] Inorganic modification agent 0.1%;

[0071] Fluid loss reducer 1.5%;

[0072] Friendly polymer treatment agent 0.2%;

[0073] The balance is water.

[0074] Embodiment 2:

[0075] The low-temperature drilling fluid of the present invention is prepared from the following components in percentage by mass:

[0076] Pulping materials 5%;

[0077] Antifreeze 12%;

[0078] Inorganic modification agent 0.1%;

[0079] Fluid loss reducer 1.5%;

[0080] Friendly polymer treatment agent 0.2%;

[0081] The balance is water.

[0082] Embodiment 3:

[0083] The low-temperature drilling fluid of the present invention is prepared from the following components in percentage by mass:

[0084] Pulping materials 5%;

[0085] Antifreeze 14%;

[0086] Inorganic modification agent 0.1%;

[0087] Fluid loss reducer 1.5%;

[0088] Friendly polymer treatment agent 0.2%;

[0089] The balance is water.

[0090] Embodiment 4:

[0091] The low-temperature drilling fluid of the present invention is prepared from the following components in percentage by mass:

[0092] Pulping materials 5%;

[0093] Antifreeze 16%;

[0094] Inorganic modification agent 0.1%;

[0095] Fluid loss reducer 1.5%;

[0096] Friendly polymer treatment agent 0.2%;

[0097] The balance is water.

[0098] The low-temperature drilling fluid for drilling in an extremely cold plateau environment prepared by the present invention can effectively cope with the low-temperature environment. As the temperature decreases, various performance parameters such as funnel viscosity are relatively stable, and the fluid has good low-temperature adaptability. Among them, the friendly polymer treatment agent gum arabic plays an important role in adjusting the viscosity and rheology of the drilling fluid.

[0099] At -20°C, the rheological parameters of the low-temperature drilling fluids prepared in Examples 1 to 4 were tested, and the results were as follows:

[0100]

[0101]

[0102] In the low temperature test, the drilling fluid maintained good rheological parameters and good performance, and had good low temperature adaptability.

[0103] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. Low-temperature drilling fluid for drilling in extreme cold plateau environments, characterized by: The low-temperature drilling fluid is prepared from the following components in percentage by mass: Pulping materials 3%-5%; Antifreeze 10%-16%; Inorganic modification agent 0.1%; Fluid loss reducer 1.5%; Friendly polymer treatment agent 0.2%; The balance is water.

2. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 1, characterized in that: The slurry making material is sodium clay.

3. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 2, characterized in that: The antifreeze agent is sodium formate.

4. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 3, characterized in that: The inorganic modification agent is sodium silicate.

5. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 4, characterized in that: The fluid loss reducer is carboxymethyl starch.

6. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 5, characterized in that: The friendly polymer treating agent is gum arabic.

7. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 6, characterized in that: The low-temperature drilling fluid is prepared from the following components in percentage by mass: Pulping materials 3%; Antifreeze 10%; Inorganic modification agent 0.1%; Fluid loss reducer 1.5%; Friendly polymer treatment agent 0.2%; The balance is water.

8. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 6, characterized in that: The low-temperature drilling fluid is prepared from the following components in percentage by mass: Pulping materials 5%; Antifreeze 12%; Inorganic modification agent 0.1%; Fluid loss reducer 1.5%; Friendly polymer treatment agent 0.2%; The balance is water.

9. The low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 6, characterized in that: The low-temperature drilling fluid is prepared from the following components in percentage by mass: Pulping materials 5%; Antifreeze 16%; Inorganic modification agent 0.1%; Fluid loss reducer 1.5%; Friendly polymer treatment agent 0.2%; The balance is water.

10. The method for preparing low-temperature drilling fluid for drilling in an extremely cold plateau environment according to claim 1, characterized in that: The method comprises: Add slurry materials to the water in a stirring state, stir and cure; Add friendly polymer treatment agent and fluid loss reducer under stirring; Then continue stirring and add antifreeze; After continuing to stir, the inorganic modifying agent is added, and after stirring and curing, the low-temperature drilling fluid is obtained.

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