CN108918327B - Novel method for optimizing drilling fluid treatment agent for coal seam characteristics - Google Patents
Novel method for optimizing drilling fluid treatment agent for coal seam characteristics Download PDFInfo
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Abstract
The invention provides a novel method for optimizing a drilling fluid treating agent for coal seam characteristics. The method comprises the steps of obtaining a pretreated coal dust sample, carrying out adsorption treatment on the pretreated coal dust sample by adopting a drilling fluid treating agent solution prepared in advance to obtain the mass of the coal dust sample after the adsorption treatment, carrying out desorption treatment on the coal dust sample after the adsorption treatment by adopting formation water to obtain the mass of the coal dust sample after the desorption treatment, and obtaining the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock according to the mass of the pretreated coal dust sample, the mass of the coal dust sample after the adsorption treatment, the mass of the coal dust sample after the desorption treatment and the mass of the drilling fluid treating agent, so that the adsorption performance and the desorption performance of the drilling fluid treating agent on the surface of the coal rock are quantitatively compared, and evaluation basis is further provided for the optimization of the drilling fluid treating agent and the protection effect of a coal reservoir in the drilling exploration process of coal bed gas.
Description
Technical Field
The invention relates to the technical field of evaluation and optimization of drilling fluid treatment agents, in particular to a novel method for optimizing a drilling fluid treatment agent for coal seam characteristics.
Background
Since the 21 st century, the world economy entered a new development cycle and the demand for oil and gas resources increased dramatically. In the face of huge energy demand, the construction and production of conventional oil gas productivity are relatively insufficient, and unconventional oil gas resources become important alternative energy sources. Natural gas is used as a clean energy source, and the yield is increased year by year. China has rich coal bed gas resources and wide distribution. The coal reservoir has the characteristics of low porosity, small permeability, large specific surface area, strong gas storage capacity and the like, and along with the large-scale drilling and development of the coal bed gas field, the coal reservoir protection and stable yield are put in an increasingly prominent position. But due to the cleat of the coal reservoir and the development of the endophytic fractures, the capillarity of the coal reservoir is prominent, the coal reservoir has a very large specific surface area, and water and polymers are easily adsorbed. In the drilling and production process, the high molecular polymer treating agent in the drilling fluid is easily adsorbed to a coal reservoir with high development of cutting joints, joints and microcracks, and has great influence on the permeability, desorption capacity, reservoir productivity and the like of coal rocks. Therefore, a drilling fluid treatment agent with small influence on the coal bed in the coal bed gas drainage and production process needs to be optimized, so that evaluation basis is provided for optimization of the drilling fluid treatment agent and protection effect of the coal reservoir in the coal bed gas drilling and production process.
In the prior art, the adsorption performance and the desorption performance of the drilling fluid treating agent on the surface of coal rock cannot be quantitatively compared, so that the influence of the drilling fluid treating agent on a coal reservoir in the process of discharging and mining coal bed gas cannot be determined, and an important evaluation index of the optimization of the coal bed drilling fluid treating agent is ignored.
Disclosure of Invention
The invention provides a novel method for optimizing a drilling fluid treating agent for coal seam characteristics, which is used for realizing quantitative comparison of adsorbability and desorption of the drilling fluid treating agent on the surface of coal rock and further providing evaluation basis for optimization of the drilling fluid treating agent in a coal seam gas drilling and production process.
The invention provides a new method for optimizing a drilling fluid treating agent for coal seam characteristics, which comprises the following steps:
obtaining a pretreated coal dust sample, and filling the pretreated coal dust sample into an adsorption column, wherein the mass of the pretreated coal dust sample is N grams;
adsorbing the pretreated coal dust sample by using a pre-prepared drilling fluid treating agent solution, drying and obtaining the mass of the coal dust sample subjected to adsorption treatment, wherein the mass of the drilling fluid treating agent in the drilling fluid treating agent solution is S g, and the mass of the coal dust sample subjected to adsorption treatment is M g;
desorbing the coal dust sample subjected to adsorption treatment by using pre-prepared formation water, drying and obtaining the mass of the coal dust sample subjected to desorption treatment, wherein the mass of the coal dust sample subjected to desorption treatment is L g;
acquiring the adsorption rate of the drilling fluid treating agent on the coal rock surface and the desorption rate of the drilling fluid treating agent on the coal rock surface according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent, wherein N, S, M, L is more than 0;
and optimizing the drilling fluid treating agent according to the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock.
Further, the obtaining of the pretreated coal dust sample includes:
obtaining a coal rock sample of a coal reservoir, crushing the coal rock sample, and screening the coal rock sample with a 80-100-mesh sieve;
soaking the coal rock sample with the 80-100 mesh sieve in the formation water for a preset time to obtain a soaked coal rock sample;
and drying the soaked coal rock sample under a first preset condition, and cooling to room temperature to obtain the pretreated coal powder sample.
Further, the step of drying the soaked coal rock sample under a first preset condition includes:
and drying the soaked coal rock sample for 24 hours at the temperature of 105 +/-5 ℃.
Further, adopting a drilling fluid treating agent solution prepared in advance to perform adsorption treatment on the pretreated coal dust sample, drying and obtaining the quality of the coal dust sample after the adsorption treatment, wherein the method comprises the following steps:
pressurizing the drilling fluid treating agent solution to enable the drilling fluid treating agent solution to pass through the pretreated coal dust sample, and draining the drilling fluid treating agent solution in the gap to obtain the coal dust sample after the drilling fluid treating agent solution passes through an adsorption column;
and drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column under a second preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after adsorption treatment.
Further, the drying treatment of the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column under a second preset condition comprises the following steps:
and drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column at 105 +/-5 ℃ for 24 hours.
Further, adopt the stratum water to carry out desorption treatment to the buggy sample after the adsorption treatment, dry and acquire the buggy sample quality after desorption treatment, include:
pressurizing the formation water, enabling the formation water to pass through the coal dust sample after adsorption treatment, and draining the formation water in the gap to obtain the coal dust sample after the formation water passes through the adsorption column;
and drying the coal dust sample after the formation water passes through the adsorption column under a third preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after desorption treatment.
Further, the coal dust sample after the formation water passes through the adsorption column is dried under a third preset condition, and the drying treatment comprises the following steps:
and drying the coal dust sample after the formation water passes through the adsorption column at 105 +/-5 ℃ for 24 hours.
Further, obtaining the adsorption rate of the drilling fluid treating agent on the coal rock surface and the desorption rate of the drilling fluid treating agent on the coal rock surface according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent, and the method comprises the following steps:
the adsorption rate of the drilling fluid treating agent on the surface of coal rock
Wherein N represents the mass of the pretreated pulverized coal sample, M represents the mass of the pulverized coal sample after adsorption treatment, and S represents the mass of the treating agent;
the desorption rate of the drilling fluid treating agent on the surface of coal rock
Wherein, N represents the mass of the pretreated coal dust sample, M represents the mass of the coal dust sample after adsorption treatment, and L represents the mass of the coal dust sample after desorption treatment.
The invention provides a new method for optimizing a drilling fluid treating agent for coal seam characteristics, which comprises the steps of obtaining a pretreated coal dust sample, adopting a drilling fluid treating agent solution prepared in advance to carry out adsorption treatment on the pretreated coal dust sample, drying and obtaining the mass of the coal dust sample after the adsorption treatment, adopting formation water to carry out desorption treatment on the coal dust sample after the adsorption treatment, drying and obtaining the mass of the coal dust sample after the desorption treatment, and further, according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent, the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock are obtained, the adsorption property and the desorption property of the drilling fluid treating agent on the surface of the coal rock are quantitatively compared, and further provides evaluation basis for the optimization of the drilling fluid treating agent and the coal reservoir protection effect in the coal bed methane drilling and exploration exploitation process.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic flow diagram of a first embodiment of a novel method for treating a drilling fluid for coal seam characteristics provided by the invention;
fig. 2 is a schematic flow chart of a second preferred novel method for the drilling fluid treatment agent used for coal seam characteristics provided by the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all 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.
Fig. 1 is a schematic flow chart of a first preferred novel method embodiment of the drilling fluid treatment agent for coal seam characteristics provided by the present invention, and as shown in fig. 1, the method of this embodiment may include:
and S101, obtaining a pretreated coal powder sample, and filling the coal powder sample into an adsorption column.
The pretreated coal powder sample can better simulate the surface of a stratum coal rock gap, wherein the mass of the pretreated coal powder sample is N g, and N is more than 0.
S102, adopting a drilling fluid treating agent solution prepared in advance to perform adsorption treatment on the pretreated coal dust sample, and obtaining the mass of the coal dust sample after the adsorption treatment.
Specifically, S g of drilling fluid treating agent is prepared into a drilling fluid treating agent solution meeting the preset concentration requirement in advance, the pretreated coal dust sample obtained in S101 is subjected to adsorption treatment by the aid of the prepared drilling fluid treating agent solution, the pretreated coal dust sample is made to adsorb drilling fluid treating agent molecules in the drilling fluid treating agent solution, and then drying is carried out, so that the coal dust sample subjected to adsorption treatment is obtained, wherein the mass of the coal dust sample subjected to adsorption treatment is M g, and M is larger than 0.
The drilling fluid treating agent is generally a high molecular polymer, and for example, a coating inhibitor of a polymer drilling fluid used in a drilling process is a high molecular polymer.
S103, carrying out desorption treatment on the coal dust sample after adsorption treatment by using formation water, drying and obtaining the mass of the coal dust sample after desorption treatment.
The method for obtaining the formation water is similar to that in the prior art, and the method for obtaining the formation water is not limited by the invention.
Further, carrying out desorption treatment on the coal dust sample subjected to adsorption treatment by using formation water, and then drying the coal dust sample so as to obtain the coal dust sample subjected to desorption treatment, wherein the mass of the coal dust sample subjected to desorption treatment is L g, and L is larger than 0.
And S104, acquiring the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent.
The mass of the pretreated coal powder is N grams, the mass of the coal powder sample after adsorption treatment is M grams, the mass of the coal powder sample after desorption treatment is L grams, and the mass of the used drilling fluid treating agent is S grams, and the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock are obtained according to the mass of the coal powder sample after different treatments.
S105, optimizing the drilling fluid treating agent according to the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock.
Specifically, according to the adsorption rate of different drilling fluid treating agents on the surface of the coal rock and the desorption rate of different drilling fluid treating agents on the surface of the coal rock, a drilling fluid treating agent with a smaller adsorption rate and a larger desorption rate is preferably used as the optimal drilling fluid treating agent.
In the new method for optimizing the drilling fluid treatment agent for coal seam characteristics provided by this embodiment, a pretreated coal dust sample is obtained, a drilling fluid treatment agent solution prepared in advance is used to perform adsorption treatment on the pretreated coal dust sample, the coal dust sample is dried and the mass of the coal dust sample after the adsorption treatment is obtained, formation water is used to perform desorption treatment on the coal dust sample after the adsorption treatment, the coal dust sample after the desorption treatment is dried and the mass of the coal dust sample after the desorption treatment is obtained, and further, according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent, the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock are obtained, so that the adsorption and desorption of the treating agent in the drilling fluid on the surface of the coal rock are quantitatively compared, and further evaluation basis is provided for the optimization of the drilling fluid treating agent in the coal bed gas drilling process.
Fig. 2 is a schematic flow chart of a second preferred novel method of the drilling fluid treatment agent for coal seam characteristics provided by the present invention, and as shown in fig. 2, the method of this embodiment may include:
s201, obtaining a coal rock sample of a coal reservoir, crushing the coal rock sample, screening the coal rock sample with a sieve of 80-100 meshes, soaking the coal rock sample with the sieve of 80-100 meshes in formation water for a preset time, obtaining the soaked coal rock sample, drying the soaked coal rock sample under a first preset condition, cooling to room temperature, obtaining the pretreated coal powder sample, and filling the pretreated coal powder sample into an adsorption column.
Optionally, in an implementation manner, a coal reservoir rock core or upward-returning rock debris is taken as a coal rock sample, the coal rock sample is crushed, and the crushed coal powder sample is sieved by using a sieve with 80-100 meshes under the U.S. Taylor standard, so that the coal rock sample meeting the 80-100 meshes is obtained.
It should be noted that, the screen mesh of 80-100 meshes is selected to process the pulverized coal rock sample, in order to obtain the coal rock sample with a suitable particle size, if the coal rock sample particle is larger, the surface area for adsorption is smaller, the adsorption and desorption phenomena for the high molecular polymer are not obvious, if the coal rock sample particle is smaller, during the adsorption treatment and desorption treatment, the drilling fluid treating agent solution and the formation water are not easy to pass through the adsorption column, and the adsorption and desorption of the drilling fluid treating agent molecule on the coal rock surface cannot be truly reflected. Of course, other suitable mesh size screens can be selected for screening according to actual conditions, and the invention is not limited to this.
Further, placing the coal rock sample with the 80-100 mesh sieve in formation water for soaking for 7 days to simulate the underground condition to wet the surface of the coal rock sample, then drying the coal rock sample soaked in the formation water for 7 days at 105 +/-5 ℃ for 24 hours, cooling to room temperature to obtain a pretreated coal powder sample, and filling the pretreated coal powder sample in an adsorption column. Wherein the mass of the pretreated coal dust sample is N g, and N is more than 0.
That is, N grams of the pretreated coal dust sample can be directly packed into the adsorption column.
Alternatively, the actual mass of the adsorption column may be obtained before the pretreated coal dust sample is packed in the adsorption column, the mass of the adsorption column packed with the pretreated coal dust sample is obtained after the pretreated coal dust sample is packed in the adsorption column, and the mass of the pretreated coal dust sample is obtained by subtracting the actual mass of the adsorption column from the mass of the adsorption column packed with the pretreated coal dust sample.
Due to the fact that loss is generated in the filling operation executing process, evaluation results of adsorbability and desorption of the drilling fluid treating agent on the coal rock surface are affected, the quality of the preprocessed coal powder sample is obtained by the method, data errors can be reduced, and the evaluation results are more accurate.
S202, pressurizing the drilling fluid treating agent solution to enable the drilling fluid treating agent solution to pass through the pretreated coal dust sample, and draining the drilling fluid treating agent solution in gaps to obtain the coal dust sample after the drilling fluid treating agent solution passes through an adsorption column; and drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column under a second preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after adsorption treatment.
Specifically, the drilling fluid treating agent solution is pressurized, so that the drilling fluid treating agent solution completely passes through the pretreated coal powder sample, the pretreated coal powder sample adsorbs high-molecular polymers in the drilling fluid treating agent solution, the drilling fluid treating agent solution in gaps is drained, no residue of the drilling fluid treating agent solution in a corresponding system is ensured, and the coal powder sample after the drilling fluid treating agent solution passes through an adsorption column is obtained.
And drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column under a second preset condition, optionally drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column at 105 +/-5 ℃ for 24 hours, and then cooling to room temperature to obtain the coal dust sample after adsorption treatment.
The method for obtaining the mass of the pulverized coal sample after adsorption treatment is the same as the method for obtaining the mass of the pretreated pulverized coal sample in the step S201, the mass of the adsorption column filled with the pulverized coal sample after adsorption treatment is firstly obtained, and then the mass of the pulverized coal sample after adsorption treatment is obtained by subtracting the actual mass of the adsorption column from the mass of the adsorption column filled with the pulverized coal sample after adsorption treatment, wherein the mass of the pulverized coal sample after adsorption treatment is M g, and M is larger than 0.
It should be noted that, in the embodiment, the manner of obtaining the mass of the coal dust sample after the adsorption treatment does not need to take out the coal dust sample after the adsorption treatment from the adsorption column and refill the coal dust sample in the adsorption column, so that the operation steps are reduced, and the accuracy of the calculation result of the adsorbability and the desorption of the subsequent drilling fluid treatment agent on the coal rock surface is improved.
S203, pressurizing the formation water to enable the formation water to pass through the coal dust sample after adsorption treatment, and draining the formation water in the gap to obtain the coal dust sample after the formation water passes through an adsorption column; and drying the coal dust sample after the formation water passes through the adsorption column under a third preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after desorption treatment.
Specifically, the formation water is pressurized, so that the formation water completely passes through the coal dust sample after adsorption treatment, and the formation water in the gap is drained, so that no formation water is left in a corresponding system, and the coal dust sample after the formation water passes through the adsorption column is obtained.
And (3) drying the coal dust sample after the formation water passes through the adsorption column under a third preset condition, optionally drying the coal dust sample after the formation water passes through the adsorption column at 105 +/-5 ℃ for 24 hours, and then cooling to room temperature to obtain the coal dust sample after desorption treatment.
The method for acquiring the mass of the coal dust sample after desorption processing is the same as the method for acquiring the mass of the coal dust sample after adsorption processing in S202, the mass of the adsorption column filled with the coal dust sample after desorption processing is firstly acquired, and then the mass of the coal dust sample after desorption processing is acquired by subtracting the actual mass of the adsorption column from the mass of the adsorption column filled with the coal dust sample after desorption processing, wherein the mass of the coal dust sample after desorption processing is L g, and L is greater than 0.
It should be noted that, in the embodiment, the method for obtaining the mass of the desorbed coal powder sample does not need to take out the desorbed coal powder sample from the adsorption column, so that the operation steps are reduced, and the accuracy of the subsequent calculation results of the adsorbability and the desorption of the drilling fluid treatment agent on the coal rock surface is improved.
S204, obtaining the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent.
Optionally, in one implementation, the adsorption rate of the drilling fluid treatment agent on the surface of the coal rock
Wherein N represents the mass of the pretreated pulverized coal sample, M represents the mass of the pulverized coal sample after adsorption treatment, and S represents the mass of the treating agent;
after desorption treatment, the desorption rate of the drilling fluid treating agent on the surface of the coal rock
Wherein, N represents the mass of the pretreated coal dust sample, M represents the mass of the coal dust sample after adsorption treatment, and L represents the mass of the coal dust sample after desorption treatment.
The adsorption performance and desorption performance of the drilling fluid treating agent on the coal rock surface can be obtained through calculation of the 2 formulas.
It should be noted that other characteristic parameters capable of reflecting the adsorbability and desorption of the drilling fluid treatment agent on the surface of the coal rock can be obtained by other calculation methods according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treatment agent.
In the above-described case of obtaining the mass of the pretreated pulverized coal sample, the mass of the pulverized coal sample after the adsorption treatment, and the mass of the pulverized coal sample after the desorption treatment, the mass of the adsorption column may be set as an unknown number, and for example, it is assumed that the mass of the adsorption column is Q, and Q is greater than 0. According to basic mathematical knowledge, substituting the mass of the pretreated coal dust sample equal to the mass of the coal dust sample filled with the pretreatment minus the mass of the adsorption column, the mass of the coal dust sample subjected to adsorption treatment equal to the mass of the coal dust sample filled with the adsorption treatment minus the mass of the adsorption column, and the mass of the coal dust sample subjected to desorption treatment equal to the mass of the coal dust sample filled with the desorption minus the mass of the adsorption column into the two formulas in the step S204, and simplifying the two calculation formulas in the step S204 to know that the adsorption rate of the drilling fluid treatment agent on the coal rock surface and the desorption rate of the drilling fluid treatment agent on the coal rock surface can be calculated according to the two formulas when the mass of the adsorption column is unknown.
The mass of the pretreated coal dust sample, the mass of the coal dust sample after adsorption treatment and the mass of the coal dust sample after desorption treatment can be obtained according to the actual mass of the adsorption column or the mass of the adsorption column is assumed as an unknown number, and the mass can be selected according to the requirements, but the invention is not limited to this.
S205, optimizing the drilling fluid treating agent according to the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock.
Specifically, according to the adsorption rate of different drilling fluid treating agents on the surface of the coal rock and the desorption rate of different drilling fluid treating agents on the surface of the coal rock, a drilling fluid treating agent with a smaller adsorption rate and a larger desorption rate is preferably used as the optimal drilling fluid treating agent.
In the new method for optimizing the drilling fluid treatment agent for coal seam characteristics provided by this embodiment, a coal rock sample of a coal reservoir is obtained, the coal rock sample is crushed, a coal rock sample satisfying a 80-100 mesh sieve is sieved, the coal rock sample of the 80-100 mesh sieve is soaked in formation water for a preset time to obtain a soaked coal rock sample, the soaked coal rock sample is dried under a first preset condition and cooled to room temperature to obtain the pretreated coal powder sample, the pretreated coal powder sample is filled in an adsorption column, then the drilling fluid treatment agent solution is pressurized to enable the drilling fluid treatment agent solution to pass through the pretreated coal powder sample side by side, the drilling fluid treatment agent solution in gaps is dried to obtain the coal powder sample after the drilling fluid treatment agent solution passes through the adsorption column, the coal powder sample after the drilling fluid treatment agent solution passes through the adsorption column is dried under a second preset condition, and cooling to room temperature to obtain the mass of the pulverized coal sample after adsorption treatment, pressurizing formation water to enable the formation water to pass through the pulverized coal sample after adsorption treatment, drying the formation water in gaps side by side to obtain the pulverized coal sample after the formation water passes through an adsorption column, drying the pulverized coal sample after the formation water passes through the adsorption column under a third preset condition, cooling to room temperature to obtain the mass of the pulverized coal sample after desorption treatment, and obtaining the adsorption rate of the drilling fluid treatment agent on the surface of the coal rock and the desorption rate of the drilling fluid treatment agent on the surface of the coal rock according to the mass of the pretreated pulverized coal sample, the mass of the pulverized coal sample after adsorption treatment, the mass of the pulverized coal sample after desorption treatment and the mass of the drilling fluid treatment agent. By selecting a coal powder sample with a proper particle size and calculating according to the formula, the adsorption performance and desorption performance of the drilling fluid treating agent on the surface of the coal rock are quantitatively reflected, and the influence of the drilling fluid treating agent on the performance of the coal rock can be further determined, so that an evaluation basis is provided for the optimization of the drilling fluid treating agent in the coal bed gas drilling and exploitation process and the coal reservoir protection effect.
The following is a detailed description of a preferred novel method of the present invention for treating a drilling fluid for coal seam characteristics, using a specific example.
This example is mainly used to optimize the natural polymer filtrate reducer WNP-2 and carboxymethyl starch CMS. The method specifically comprises the following steps:
firstly, obtaining a coal rock sample of a No. 8 coal bed in a raise zone of a coal bed gas field in Yunnan Dong Qian Wen province, crushing the coal rock sample, screening the coal rock sample meeting a sieve of 80-100 meshes, soaking the coal rock sample with the sieve of 80-100 meshes in formation water for 7 days, drying the soaked coal rock sample for 24 hours at 105 +/-5 ℃ to obtain a pretreated coal powder sample, and filling the obtained pretreated coal powder sample in an adsorption column. Wherein the mass of the adsorption column filled with the pretreated coal powder sample is 135.6571 g.
And then, pressurizing the natural polymer filtrate reducer WNP-2 solution to enable the natural polymer filtrate reducer WNP-2 solution to enter an adsorption column, drying the natural polymer filtrate reducer WNP-2 solution in the gap side by side, and drying the pretreated coal dust sample placed in the adsorption column for 24 hours at 105 +/-5 ℃ when the natural polymer filtrate reducer WNP-2 solution passes through the adsorption column to obtain the adsorption-treated coal dust sample, wherein the mass of the adsorption column filled with the adsorption-treated coal dust sample is 135.8026 g.
The WNP-2 solution of the natural polymer fluid loss additive prepared in advance is 2% WNP-2 solution of the natural polymer fluid loss additive prepared from 500 ml of water and 10 g of WNP-2 of the natural polymer fluid loss additive.
And further pressurizing 500 ml of formation water, enabling the formation water to enter the adsorption column, and draining the formation water in the gap, fully desorbing the coal dust sample after adsorption treatment by the formation water when the formation water passes through the adsorption column, and drying for 24 hours at 105 +/-5 ℃ to obtain the coal dust sample after desorption treatment, wherein the mass of the adsorption column filled with the coal dust sample after desorption treatment is 135.7877 g.
Wherein, if the mass of the adsorption column is unknown Q and Q is greater than 0, N is 135.6571-Q, M is 135.8026-Q, L is 135.7877-Q, and S is 10.0.
Alternatively, in another implementation, the actual mass of the adsorption column may be obtained before the column is filled with the pre-treated coal dust sample. After the above steps are performed, the mass of the adsorption column is subtracted from the mass of the adsorption column filled with the pretreated pulverized coal sample to obtain the mass of the pretreated pulverized coal sample, correspondingly, the mass of the adsorption column is subtracted from the mass of the adsorption column filled with the adsorption-treated pulverized coal sample to obtain the mass of the adsorption-treated pulverized coal sample, and the mass of the adsorption column is subtracted from the mass of the adsorption column filled with the desorption-treated pulverized coal sample to obtain the mass of the desorption-treated pulverized coal sample.
Further, the adsorption rate of the natural polymer filtrate reducer WNP-2 on the surface of the coal rock sample and the desorption rate of the natural polymer filtrate reducer WNP-2 on the surface of the coal rock sample are obtained according to the following two formulas.
Specifically, the adsorption rate of the natural polymer filtrate reducer WNP-2 on the surface of the coal rock sample
WhereinN represents the mass of the pretreated coal dust sample, M represents the mass of the coal dust sample after adsorption treatment, and S represents the mass of the natural polymer filtrate reducer WNP-2.
Desorption rate of natural polymer filtrate reducer WNP-2 on surface of coal rock sample
Wherein, N represents the mass of the pretreated coal dust sample, M represents the mass of the coal dust sample after adsorption treatment, and L represents the mass of the coal dust sample after desorption treatment.
And replacing the natural polymer filtrate reducer WNP-2 with carboxymethyl starch CMS, and repeating the steps to obtain the adsorption rate of the carboxymethyl starch CMS on the surface of the coal rock and the desorption rate of the carboxymethyl starch CMS on the surface of the coal rock. The following results were obtained according to the above procedure, as shown in table 1:
wherein, the adsorption rate in table 1 refers to the adsorption rate of the natural polymer filtrate reducer WNP-2 or carboxymethyl starch CMS on the surface of coal rock, and the desorption rate refers to the desorption rate of the natural polymer filtrate reducer WNP-2 or carboxymethyl starch CMS on the surface of coal rock.
From the data, it can be seen that the adsorption capacity and desorption capacity of the natural polymer filtrate reducer WNP-2 on the surface of coal rock are relatively large, while the adsorption capacity and desorption capacity of carboxymethyl starch CMS on the surface of coal rock are relatively small, so that the preferable carboxymethyl starch CMS as the filtrate reducer can reduce the adsorption of the drilling fluid treatment agent on the surface of coal rock.
Claims (6)
1. A novel method for optimizing a drilling fluid treatment agent for coal seam characteristics is characterized by comprising the following steps:
obtaining a pretreated coal dust sample, and filling the pretreated coal dust sample into an adsorption column, wherein the mass of the pretreated coal dust sample is N grams;
adsorbing the pretreated coal dust sample by using a pre-prepared drilling fluid treating agent solution, drying and obtaining the mass of the coal dust sample subjected to adsorption treatment, wherein the mass of the drilling fluid treating agent in the drilling fluid treating agent solution is S g, and the mass of the coal dust sample subjected to adsorption treatment is M g;
carrying out desorption treatment on the coal dust sample subjected to adsorption treatment by using formation water, drying and obtaining the mass of the coal dust sample subjected to desorption treatment, wherein the mass of the coal dust sample subjected to desorption treatment is L g;
acquiring the adsorption rate of the drilling fluid treating agent on the coal rock surface and the desorption rate of the drilling fluid treating agent on the coal rock surface according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treating agent, wherein N, S, M, L is more than 0;
the drilling fluid treating agent is optimized according to the adsorption rate of the drilling fluid treating agent on the surface of the coal rock and the desorption rate of the drilling fluid treating agent on the surface of the coal rock;
the method for obtaining the pretreated coal dust sample comprises the following steps:
obtaining a coal rock sample of a coal reservoir, crushing the coal rock sample, and screening the coal rock sample with a 80-100-mesh sieve;
soaking the coal rock sample with the 80-100 mesh sieve in the formation water for a preset time to obtain a soaked coal rock sample;
drying the soaked coal rock sample under a first preset condition, and cooling to room temperature to obtain the pretreated coal powder sample;
the step of drying the soaked coal rock sample under a first preset condition comprises the following steps:
and drying the soaked coal rock sample for 24 hours at the temperature of 105 +/-5 ℃.
2. The method of claim 1, wherein the adsorbing the pre-treated coal dust sample with a pre-formulated drilling fluid treatment agent solution, drying and obtaining the mass of the adsorbed coal dust sample comprises:
pressurizing the drilling fluid treating agent solution to enable the drilling fluid treating agent solution to pass through the pretreated coal dust sample, and discharging the drilling fluid treating agent solution in the gap to obtain the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column;
and drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column under a second preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after adsorption treatment.
3. The method of claim 2, wherein the drying of the coal dust sample after the drilling fluid treatment agent solution passes through the adsorption column under a second preset condition comprises:
and drying the coal dust sample after the drilling fluid treating agent solution passes through the adsorption column at 105 +/-5 ℃ for 24 hours.
4. The method according to claim 3, wherein the desorption treatment of the coal dust sample after the adsorption treatment by using formation water, drying and obtaining the mass of the coal dust sample after the desorption treatment comprises:
pressurizing the formation water, enabling the formation water to pass through the coal dust sample after adsorption treatment, and draining the formation water in the gap to obtain the coal dust sample after the formation water passes through the adsorption column;
and drying the coal dust sample after the formation water passes through the adsorption column under a third preset condition, and cooling to room temperature to obtain the mass of the coal dust sample after desorption treatment.
5. The method according to claim 4, wherein the coal dust sample after the formation water passes through the adsorption column is dried under a third preset condition, and the method comprises the following steps:
and drying the coal dust sample after the formation water passes through the adsorption column at 105 +/-5 ℃ for 24 hours.
6. The method according to any one of claims 1 to 5, wherein obtaining the adsorption rate of the drilling fluid treatment agent on the coal rock surface and the desorption rate of the drilling fluid treatment agent on the coal rock surface according to the mass of the pretreated coal powder sample, the mass of the coal powder sample after adsorption treatment, the mass of the coal powder sample after desorption treatment and the mass of the drilling fluid treatment agent comprises:
the adsorption rate of the drilling fluid treating agent on the surface of coal rock
Wherein N represents the mass of the pretreated pulverized coal sample, M represents the mass of the pulverized coal sample after adsorption treatment, and S represents the mass of the drilling fluid treating agent;
the desorption rate of the drilling fluid treating agent on the surface of coal rock
Wherein, N represents the mass of the pretreated coal dust sample, M represents the mass of the coal dust sample after adsorption treatment, and L represents the mass of the coal dust sample after desorption treatment.
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