Micro-solid-phase completion fluid dispersing agent as well as preparation and application thereof

Abstract

The invention discloses a micro-solid phase completion fluid dispersing agent, which has a structural formula shown as a formula (I), and in the formula (I), R is selected from-C17H35,-C12H25 or C15H31. The invention also discloses a preparation method and application thereof. The micro-solid-phase completion fluid dispersing agent disclosed by the invention has double effects of surface activity and complexation, has a remarkable inhibition effect on coagulation and degradation of a weighting material, and has relatively excellent scale inhibition capability. According to the integrated agent, a traditional dispersion mode of respectively adding a surfactant and a complexing agent is avoided, and the problem that the density of the completion fluid is reduced due to the fact that the surfactant and the complexing agent are added in a large scale is avoided while feeding is simple and convenient.

Description

Technical Field

[0001] This invention relates to a micro-solid phase completion fluid dispersant, its preparation, and its application. Background Technology

[0002] Completion fluid is the drilling fluid used when drilling into oil and gas formations. Its performance directly affects the well's production. The density of the completion fluid is one of its most important properties. It is primarily used to regulate the hydrostatic pressure of the completion fluid column to balance formation pore pressure and ensure operational safety. Sometimes it is also used to balance formation structural stress to prevent well collapse. The density of the completion fluid must meet geological and engineering requirements. If the density is too high, it can cause a series of problems, including excessive thickening of the completion fluid, easy leakage, decreased drilling speed, damage to oil and gas formations, and increased completion fluid costs. Conversely, if the density is too low, it can easily lead to well kicks or even blowouts, and sometimes well collapse, reduced well diameter, and decreased cuttings carrying capacity. Therefore, it is essential to accurately and reasonably determine the drilling density parameters for different well sections and to continuously monitor and adjust them during the drilling process.

[0003] Adding various weighting materials such as barite and limestone is the most common method to increase the density of completion fluid. However, the buoyancy of these weighting material particles is limited, and due to gravity, high-density solid weighting materials easily settle to the bottom of the drilling fluid. This rapid settling of the weighting material causes a significant change in the drilling fluid density, leading to various drilling problems such as stuck pipe and burial, and in severe cases, even well blowouts. Furthermore, the weighting material can precipitate in the completion fluid, thus affecting its properties.

[0004] To address the stability issue of weighting agents in completion fluids, dispersants are typically added to high-density completion fluids to prevent particle aggregation and degradation. Current research on drilling fluid dispersants is limited. Currently, viscosity reducers are often used instead of dispersants in high-density drilling fluids in China, which can provide some dispersion for weighting materials, but the effect is not significant. Summary of the Invention

[0005] In response to the current serious agglomeration problem of weighting materials in micro-solid phase completion fluids, the purpose of this invention is to prepare a novel micro-solid phase completion fluid dispersant to inhibit the agglomeration and degradation of weighting particles in micro-solid phase completion fluids.

[0006] First, long-chain fatty acids are combined with carboxyethyl ethylenediamine via a simple amide reaction at high temperature. Then, the product obtained in the previous step is combined with organophosphoric acid via esterification to obtain an organophosphoric acid containing long-chain alkyl groups. Experimental results show that it not only acts as a surfactant but also possesses complexing properties, effectively inhibiting the aggregation of weighting materials in the completion fluid.

[0007] As one aspect of the present invention, there is a micro-solid phase completion fluid dispersant having a structural formula as shown in formula (I):

[0008]

[0009] (I), where R is selected from -C 17 H 35 -C 12 H 25 Or C 15 H 31 .

[0010] As another aspect of the present invention, a method for preparing the above-mentioned micro-solid phase completion fluid dispersant is provided, comprising:

[0011] (1) Stearic acid and carboxyethyl ethylenediamine undergo an amidation reaction under the catalysis of xylene to give a long-chain fatty amide;

[0012] (2) The long-chain fatty amide obtained in step (1) undergoes esterification with organophosphonic acid under the catalysis of H2SO4.

[0013] In a specific embodiment, in step (1), the weight ratio of stearic acid to carboxyethyl ethylenediamine is (2.7-2.8):1.

[0014] In a specific embodiment, in step (2), the weight ratio of the long-chain fatty amide obtained in step (1) to the organophosphonic acid is (1.3~1.4):1.

[0015] In a specific embodiment, the amidation reaction in step (1) is carried out at 120-160°C.

[0016] In a specific embodiment, the reaction time of the amidation reaction in step (1) is 10-12 h.

[0017] In a specific embodiment, the esterification reaction in step (2) is carried out at 60-70°C.

[0018] In a specific embodiment, the reaction time of the esterification reaction in step (2) is 6-9 hours.

[0019] In a specific embodiment, the H2SO4 in step (2) is H2SO4 with a mass fraction of 98%.

[0020] As another aspect of the present invention, it relates to the application of the above-mentioned micro-solid phase completion fluid dispersant in oil and gas development.

[0021] In another aspect, the invention relates to a drilling fluid comprising the aforementioned micro-solid phase completion fluid dispersant. The modes of action of its components are briefly described below:

[0022] A surface-active long-chain fatty acid, characterized in that the long-chain fatty acid has a dispersing effect and has the structural formula (II) as follows (where R is selected from -C). 12 H 25 -C 15 H3 or -C 17 H 35 ):

[0023]

[0024] A carboxydiamine with complexing effect, characterized in that it has the following structural formula (Ⅲ):

[0025]

[0026] An organophosphonic acid with a complexing effect, characterized in that it has the following structural formula (IV):

[0027]

[0028] This invention presents a novel long-chain alkyl dispersant prepared through a two-step chemical reaction. This dispersant not only contains surface-active long-chain alkyl groups but also phosphate and carboxylic acid functional groups with complexing properties, thus exhibiting both surface activity and complexing effects. It significantly inhibits the aggregation and degradation of weighting materials. This integrated agent avoids the traditional dispersion method of separately adding surfactants and complexing agents, simplifying the feeding process while avoiding the problem of decreased well completion fluid density caused by large-scale addition of surfactants and complexing agents. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] This invention provides a micro-solid phase completion fluid dispersant, which forms a long-chain alkyl dispersant with both surface activity and complexation effect through an amidation reaction between stearic acid and carboxyethyl ethylenediamine and an esterification reaction between organophosphonic acid and the product of the first step. It has a significant inhibitory effect on the aggregation and decomposition of weighting materials in the completion fluid.

[0031] Unless otherwise specified, the parts referred to in this application are parts by mass, and the ratios referred to are mass ratios.

[0032] Example 1: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0033] 1) Dodecyl fatty acid and carboxyethyl ethylenediamine were added sequentially to a 250 mL three-necked flask at a mass ratio of 2.7:1. Xylene was added as a catalyst, and the mixture was heated to 120 °C to carry out the reaction. The reaction was stopped after 10 h. After the reaction solution cooled, the catalyst was filtered off, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0034] 2) The product obtained in step 1) and organophosphoric acid were added to a 250 mL three-necked flask at a ratio of 1.3:1. Then, 2 mL of 98% concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 60 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was returned to the three-necked flask for recycling. The reaction was stopped after 6 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out and purified to obtain the micro-solid phase completion fluid dispersant.

[0035] The structural formula of the micro-solid phase completion fluid dispersant obtained in this embodiment is:

[0036]

[0037] The chemical reaction process in this embodiment is illustrated below:

[0038]

[0039] A 1% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 16 hours, the settling coefficient SF was measured and compared with a blank sample without dispersant. It can be seen that after adding the micro-solid phase completion fluid dispersant, the settling coefficient of the micro-solid phase completion fluid decreased from 0.564 to 0.553.

[0040] Table 1 Settling coefficients of micro-solid phase completion fluid after 16 hours of aging

[0041]

[0042] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0043] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0044]

[0045] Example 2: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0046] Dodecyl fatty acid and carboxyethyl ethylenediamine (mass ratio 2.75:1) were sequentially added to a 250 mL three-necked flask, followed by the addition of a suitable amount of xylene catalyst. The mixture was heated to 140 °C for reaction. The reaction was stopped after 11 hours. After the reaction solution cooled, the catalyst was filtered out by vacuum filtration and purified by recrystallization from methanol to obtain the product of the first step (long-chain fatty amide). 2) The product obtained in step 1) and organic phosphoric acid were sequentially added to a 250 mL three-necked flask in a ratio of 1.36:1. Then, 2 mL of 98% concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 65 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was recycled back to the three-necked flask for reuse. The reaction was stopped after 8 hours when no water was distilled out. After the reaction solution cooled, the catalyst was filtered out and purified to obtain a micro-solid phase completion fluid dispersant.

[0047] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0048]

[0049] A 1% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient of the micro-solid phase completion fluid dispersant decreased from 0.651 to 0.527, and the dispersant's dispersion effect became more significant with prolonged aging time.

[0050] Table 2 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0051]

[0052] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0053] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0054]

[0055] Example 3: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0056] Dodecyl fatty acid and carboxyethyl ethylenediamine were added sequentially to a 250 mL three-necked flask at a mass ratio of 2.8:1, followed by the addition of an appropriate amount of xylene catalyst. The mixture was heated to 160 °C to initiate the reaction. The reaction was stopped after 12 hours. After the reaction solution cooled, the catalyst was filtered off by vacuum filtration, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0057] 2) The product obtained in step 1) and organophosphoric acid were added sequentially to a 250 mL three-necked flask in a ratio of 1.4:1. Then, 2 mL of 98% concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 70 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was recycled back to the three-necked flask for reuse. The reaction was stopped after 9 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out, purified, and a micro-solid phase completion fluid dispersant was obtained.

[0058] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0059]

[0060] A 1.5% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient (SF) was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient decreased from 0.651 to 0.461, and the dispersion effect became more significant with increasing dispersant content.

[0061] Table 3 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0062]

[0063] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0064] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0065]

[0066] Example 4: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0067] A pentadecyl fatty acid and carboxyethyl ethylenediamine were sequentially added to a 250 mL three-necked flask at a mass ratio of 2.75:1, followed by the addition of an appropriate amount of xylene as a catalyst. The mixture was heated to 160 °C to initiate the reaction. The reaction was stopped after 12 hours. After the reaction solution cooled, the catalyst was filtered off by vacuum filtration, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0068] 2) The product obtained in step 1) and organophosphoric acid were added sequentially to a 250 mL three-necked flask in a ratio of 1.3:1. Then, 2 mL of 98% concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 65 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was recycled back to the three-necked flask. The reaction was stopped after 9 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out, purified, and a micro-solid phase completion fluid dispersant was obtained.

[0069] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0070]

[0071] A 1% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient (SF) was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient decreased from 0.651 to 0.510, and the dispersion effect became more significant with the increase of the long-chain alkyl chain of the dispersant.

[0072] Table 3 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0073]

[0074] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0075] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0076]

[0077] Example 5: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0078] A pentadecyl fatty acid and carboxyethyl ethylenediamine were sequentially added to a 250 mL three-necked flask at a mass ratio of 2.8:1, followed by the addition of an appropriate amount of xylene as a catalyst. The mixture was heated to 160 °C to initiate the reaction. The reaction was stopped after 12 hours. After the reaction solution cooled, the catalyst was filtered off by vacuum filtration, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0079] 2) The product obtained in step 1) and organophosphoric acid were added sequentially to a 250 mL three-necked flask in a ratio of 1.4:1. Then, 2 mL of 98% concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 70 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was recycled back to the three-necked flask for reuse. The reaction was stopped after 6 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out, purified, and a micro-solid phase completion fluid dispersant was obtained.

[0080] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0081]

[0082] A 1.5% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient of the micro-solid phase completion fluid dispersant decreased from 0.651 to 0.441, and the dispersion effect became more significant with increasing dispersant content.

[0083] Table 3 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0084]

[0085]

[0086] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0087] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0088]

[0089] Example 6: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0090] A heptadecanyl fatty acid and carboxyethyl ethylenediamine were sequentially added to a 250 mL three-necked flask at a mass ratio of 2.7:1, followed by the addition of an appropriate amount of xylene as a catalyst. The mixture was heated to 160 °C to initiate the reaction. The reaction was stopped after 10 h. After the reaction solution cooled, the catalyst was filtered off by vacuum filtration, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0091] 2) The product obtained in step 1) and organophosphoric acid were added sequentially to a 250 mL three-necked flask at a ratio of 1.35:1. Then, 2 mL of concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 60 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was returned to the three-necked flask for recycling. The reaction was stopped after 8 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out, purified, and a micro-solid phase completion fluid dispersant was obtained.

[0092] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0093]

[0094] A 1% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient (SF) was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient decreased from 0.651 to 0.491, and the dispersion effect became more significant with the increase of the long-chain alkyl chain of the dispersant.

[0095] Table 3 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0096]

[0097] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0098] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0099]

[0100] Example 7: Preparation and Dispersing Ability Evaluation of Micro-Solid Completion Fluid Dispersant

[0101] A heptadecanyl fatty acid and carboxyethyl ethylenediamine were sequentially added to a 250 mL three-necked flask at a mass ratio of 2.8:1, followed by the addition of an appropriate amount of xylene as a catalyst. The mixture was heated to 160 °C to initiate the reaction. The reaction was stopped after 12 hours. After the reaction solution cooled, the catalyst was filtered off by vacuum filtration, and the product of the first step (long-chain fatty amide) was obtained by recrystallization from methanol.

[0102] 2) The product obtained in step 1) and organophosphoric acid were added sequentially to a 250 mL three-necked flask in a ratio of 1.4:1. Then, 2 mL of concentrated sulfuric acid was slowly added as a catalyst, and the mixture was heated to 70 °C for reaction. Water generated during the reaction was released as needed, and the water-carrying agent was recycled back to the three-necked flask. The reaction was stopped after 9 hours when no more water was distilled off. After the reaction solution cooled, the catalyst was filtered out, purified, and a micro-solid phase completion fluid dispersant was obtained.

[0103] The chemical structure of the micro-solid phase completion fluid dispersant obtained in this embodiment is as follows:

[0104]

[0105] A 1.5% micro-solid phase completion fluid dispersant was added to the completion fluid containing weighting materials. After aging for 24 hours, the settling coefficient (SF) was measured and compared with a blank sample without dispersant. It can be seen that after adding this long-chain alkyl dispersant to the micro-solid phase completion fluid, the settling coefficient decreased from 0.651 to 0.402, and the dispersion effect became more significant with increasing dispersant content.

[0106] Table 3 Settling coefficients of micro-solid phase completion fluid after 24 hours of aging

[0107]

[0108] Meanwhile, the scale inhibition performance of the prepared micro-solid phase completion fluid dispersant was determined according to the standard method for determining the scale inhibition performance of water treatment agents (GB / T 22626-2008). The specific test results are shown in Table 2 below.

[0109] Table 2. Scale inhibition effect of micro-solid phase completion fluid on calcium carbonate.

[0110]

[0111] The comparison of the above examples shows that a micro-solid phase completion fluid dispersant with excellent dispersing properties was synthesized through a simple two-step reaction with mild reaction conditions. Aging experiments show that after adding more than 1% of the micro-solid phase completion fluid dispersant of this invention, the settling coefficient of the completion fluid significantly decreased, indicating that the micro-solid phase completion fluid dispersant of this invention enhances the dispersion ability of the completion fluid, and the dispersion effect gradually increases with the increase of the content of the micro-solid phase completion fluid dispersant of this invention.

[0112] Furthermore, the micro-solid phase completion fluid dispersant of this invention exhibits excellent dispersing performance as well as excellent scale inhibition ability. After adding more than 1% of the micro-solid phase completion fluid dispersant, the scale inhibition rate of the system for calcium carbonate can reach over 74%.

[0113] This invention prepares a micro-solid phase completion fluid dispersant with excellent dispersing properties through a simple two-step amide reaction. While playing a dispersing role, the dispersant also has excellent scale inhibition properties, realizing the "one agent, multiple functions" effect of oilfield chemicals.

[0114] In this invention, "room temperature" specifically refers to 20–25°C.

[0115] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A micro-solid phase completion fluid dispersant, characterized in that, It has the structural formula shown in equation (I): (I), where R is selected from -C 17 H 35 -C 12 H 25 Or C 15 H 31 .

2. A method for preparing the micro-solid phase completion fluid dispersant according to claim 1, characterized in that, include: (1) Stearic acid and carboxyethyl ethylenediamine undergo an amidation reaction under the catalysis of xylene to give a long-chain fatty amide; (2) The long-chain fatty amide obtained in step (1) undergoes esterification with organophosphonic acid under the catalysis of H2SO4.

3. The method according to claim 2, characterized in that, In step (1), the weight ratio of stearic acid to carboxyethyl ethylenediamine is (2.7-2.8):

1.

4. The method according to claim 2, characterized in that, In step (2), the weight ratio of the long-chain fatty amide obtained in step (1) to the organophosphonic acid is (1.3-1.4):

1.

5. The method according to claim 2, characterized in that, The amidation reaction in step (1) is carried out at 120-160°C.

6. The method according to claim 5, characterized in that, The reaction time for the amidation reaction in step (1) is 10-12 h.

7. The method according to claim 2, characterized in that, The esterification reaction in step (2) is carried out at 60-70°C.

8. The method according to claim 7, characterized in that, The reaction time for the esterification reaction in step (2) is 6-9 hours.

9. The application of the micro-solid phase completion fluid dispersant of claim 1 in oil and gas development.

10. A drilling fluid, characterized in that, It contains the micro-solid phase completion fluid dispersant as described in claim 1.

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