Disclosure of Invention
The invention aims to provide a preparation method and preparation equipment of foam drilling fluid for three-gas open-hole exploitation, so that the density of the foam drilling fluid can be lower than 1.00g/cm3And the density is adjustable, the requirements of various reservoir layers can be met, and the system stability is effectively improved.
In order to solve the technical problem, the invention provides a preparation method of foam drilling fluid for three-gas open hole exploitation, which comprises the following steps:
the method comprises the following steps:
s1: respectively preparing clear water, a treating agent and a stabilizing agent, wherein the treating agent comprises a foam stabilizer and a foaming agent, the foam stabilizer comprises carboxymethyl starch, carboxyethyl starch and carboxymethyl cellulose, and the foaming agent comprises sodium dodecyl benzene sulfonate, trimethyl ethyl lactone and octadecanol;
the mass ratio of the carboxymethyl starch to the carboxyethyl starch to the carboxymethyl cellulose to the sodium dodecyl benzene sulfonate to the trimethyl ethyl lactone to the octadecanol is as follows: (7-13): (7-13): (3-7): (3-5): (4-8): (0.5 to 2);
s2: adding the clear water into a slurry preparation tank;
s3: adding the foam stabilizer into the slurry preparation tank in the step S2, continuously mixing, and performing the step S4;
s4: adding the foaming agent and the stabilizing agent into the slurry preparation tank.
The foam drilling fluid comprises clear water, a treating agent and a stabilizing agent, wherein the treating agent comprises a foam stabilizer and a foaming agent, and carboxymethyl starch in the foam stabilizer has good thickening, stabilizing, water-retaining, film-forming and suspending effects after being dissolved in water, is convenient to use, and is safe and environment-friendly; the carboxyethyl starch plays a role in separation inhibition, and the carboxyethyl starch can stabilize the foaming process in the foaming process of the foaming agent; the aqueous solution of the carboxymethyl cellulose has the effects of thickening, film forming, adhesion, water retention, colloid protection, emulsification, suspension and the like, and the foam drilling fluid containing the carboxymethyl cellulose can enable a well wall to form a thin and firm filter cake with low permeability, so that the pollution of the foam drilling fluid to a reservoir is reduced, and the influence of the foam drilling fluid on the permeability is reduced. The three foam stabilizers are proportioned according to the proportion, so that the density of the foam drilling fluid can be stably reduced in the foaming process of the foaming agent, the stability of a foam structure after the foaming agent is foamed can be improved, the bubbles are separated from each other, the bubbles are similar to balloons, and the structural stability is good.
Dodecyl benzene sulfonic acid in foaming agentSodium as an anionic surfactant has good surface activity and strong hydrophilicity, and is used as an air entraining agent; trimethylcaprolactone is a commonly used blowing agent; octadecanol has good emulsifying property, and the three foaming agents can be foamed in a water-based environment according to the mixture ratio, so that the density of the foam drilling fluid obtained after the treating agent is dissolved in clear water is lower than that of the clear water, namely 1.00g/cm3The foam drilling fluid has the following effects that the foaming effect can be ensured to be in a reasonable range, and the density requirement of the foam drilling fluid can be met.
In detail, the preparation of the foam drilling fluid is carried out in a slurry preparation tank, so that the field preparation is convenient to realize, and in the preparation process, a mixing device is required to carry out continuous mixing operation on the liquid in the slurry preparation tank in the whole process. When the treating agent is added into the slurry preparation tank, the foam stabilizer (carboxymethyl starch, carboxyethyl starch and carboxymethyl cellulose) needs to be slowly added, and the foam stabilizer is continuously mixed after being added, so that the foam stabilizer can be fully dissolved in clear water, and a stable foaming environment is provided for a foaming agent to be added subsequently; then slowly adding a foaming agent (sodium dodecyl benzene sulfonate, trimethyl ethyl lactone and octadecanol) and a stabilizing agent, and continuously mixing until the foaming agent can be fully dissolved in water and fully foamed, wherein the foam can separate each bubble from each other under the action of the foam stabilizing agent and improve the stability of each bubble. The whole process requires mixing operation, so that the foaming is more complete, the foam stability is better, and the foam drilling fluid can be ensured to play a cooling role on the drill bit and have higher rock carrying capacity and the like.
Optionally, the clear water is field water and the stabilizer is sodium bicarbonate.
Optionally, in step S1, the mass ratio of the clean water, the treating agent and the stabilizing agent is (700-1300): (25-45) (0.5-2).
Optionally, after the step S4, the method further includes the following steps:
s5: detecting whether the density and rheological index of the foam drilling fluid in the slurry preparation tank reach respective target values;
if the density and rheological index reach respective target values, the preparation of the foam drilling fluid is finished;
if the density and rheological index do not reach their respective target values, go to step S6;
s6: if the density is higher than the target value and the rheological index is lower than the target value, adding each treating agent into the slurry preparation tank according to the mass ratio in the step S1;
and if the density is lower than the target value and the rheological index is higher than the target value, adding the clean water into the slurry preparation tank.
Optionally, the target value of the density is 0.75g/cm3~1.00g/cm3(ii) a The target values for the rheological index include: an apparent viscosity of 15 to 35 mPas, a plastic viscosity of 8 to 25 mPas, a dynamic shear force of 10 to 25 mPas, and a dynamic plastic ratio of 0.6 to 1.0 Pa/(mPas).
Optionally, in step S3, adding the foam stabilizer into the slurry preparation tank includes sequentially adding the carboxymethyl starch, the carboxyethyl starch, and the carboxymethyl cellulose into the slurry preparation tank; in step S4, adding a foaming agent into the slurry preparation tank includes sequentially adding the sodium dodecylbenzenesulfonate, the trimethylethyllactone, and the octadecanol into the slurry preparation tank.
Optionally, in step S3, after adding the foam stabilizer and continuously mixing for a first preset time, the process proceeds to step S4; in step S4, mixing is continued for a second predetermined time after the addition of the blowing agent.
Optionally, the first preset time and the second preset time are 20min to 30 min.
In addition, the invention also provides a preparation device of the foam drilling fluid for three-gas open hole exploitation horizontal well, which is based on the preparation method of the foam drilling fluid and comprises a slurry preparation tank and a mixing device, wherein the mixing device is used for mixing the liquid in the slurry preparation tank.
The technical effect of the preparation equipment based on the preparation method of the foam drilling fluid is similar to that of the preparation method, and is not repeated herein for saving space.
Optionally, the mixing device is a stirring device arranged in the slurry preparation tank; or the mixing device comprises a fluid pump and a pipeline, the fluid pump is arranged outside the slurry preparation tank, the pipeline is communicated with the slurry preparation tank and forms a circulating fluid pipeline, and liquid in the circulating fluid pipeline can circulate under the action of the fluid pump.
Optionally, the volume of the slurry preparation tank is not less than 10m3If the mixing device is a stirring device, the stirring speed is not less than 70r/min, and if the mixing device comprises the fluid pump and the pipeline, the discharge capacity of the fluid pump is not less than 12m3/h。
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1-4, fig. 1 is a flow chart of a method for preparing a foam drilling fluid for three-gas open hole production according to an embodiment of the present invention; FIG. 2 is a detailed flow diagram of a method for formulating a foam drilling fluid for open-hole production of three gases according to an embodiment of the present invention; FIG. 3 is a schematic structural diagram of a foam drilling fluid preparation device for open-hole three-gas production provided by an embodiment of the invention; FIG. 4 is another schematic structural diagram of a foam drilling fluid preparation device for open-hole three-gas production according to an embodiment of the invention.
The embodiment of the invention provides a preparation method and preparation equipment of foam drilling fluid for three-gas open-hole exploitation, wherein the three-gas open-hole exploitation refers to a mode of realizing development in an open-hole completion mode when three unconventional natural gases such as sandstone gas, coal bed gas and shale gas are jointly exploited in a multilayer manner.
The preparation method of the foam drilling fluid in the embodiment comprises the following steps:
s1: respectively preparing clear water, a treating agent and a stabilizing agent, wherein the treating agent comprises a foam stabilizer and a foaming agent, the foam stabilizer comprises carboxymethyl starch, carboxyethyl starch and carboxymethyl cellulose, and the foaming agent comprises sodium dodecyl benzene sulfonate, trimethyl ethyl lactone and octadecanol;
the mass ratio of the carboxymethyl starch to the carboxyethyl starch to the carboxymethyl cellulose to the sodium dodecyl benzene sulfonate to the trimethyl ethyl lactone to the octadecanol is as follows: (7-13): (7-13): (3-7): (3-5): (4-8): (0.5 to 2);
s2: adding the clean water into the slurry preparation tank 1;
s3: adding a foam stabilizer into the slurry preparation tank 1 in the step S2, continuously mixing, and entering the step S4;
s4: a foaming agent and a stabilizing agent are added into the slurry preparation tank 1.
Accordingly, the preparation equipment based on the preparation method in the embodiment includes the slurry preparation tank 1 and a mixing device, wherein the mixing device is used for mixing the liquid in the slurry preparation tank 1.
The foam drilling fluid comprises clear water, a treating agent and a stabilizing agent, wherein the treating agent comprises a foam stabilizer and a foaming agent, and carboxymethyl starch in the foam stabilizer has good thickening, stabilizing, water-retaining, film-forming and suspending effects after being dissolved in water, is convenient to use, and is safe and environment-friendly; the carboxyethyl starch plays a role in separation inhibition, and the carboxyethyl starch can stabilize the foaming process in the foaming process of the foaming agent; the aqueous solution of carboxymethyl cellulose (CMC) has the functions of thickening, film forming, adhesion, water retention, colloid protection, emulsification, suspension and the like, and the foam drilling fluid containing carboxymethyl cellulose (CMC) can enable a well wall to form a filter cake which is thin, firm and low in permeability, so that the pollution of the foam drilling fluid to a reservoir stratum is reduced, and the influence of the foam drilling fluid on the permeability is reduced. The three foam stabilizers are proportioned according to the proportion, so that the density of the foam drilling fluid can be stably reduced in the foaming process of the foaming agent, the stability of a foam structure after the foaming agent is foamed can be improved, the bubbles are separated from each other, the bubbles are similar to balloons, and the structural stability is good.
The sodium dodecyl benzene sulfonate in the foaming agent is used as an anionic surfactant, has good surface activity and stronger hydrophilicity and is used as an air entraining agent; trimethylcaprolactone is a commonly used blowing agent; octadecanol has good emulsifying property, and the three foaming agents can be foamed in a water-based environment according to the mixture ratio, so that the density of the foam drilling fluid obtained after the treating agent is dissolved in clear water is lower than that of the clear water, namely 1.00g/cm3The foam drilling fluid has the following effects that the foaming effect can be ensured to be in a reasonable range, and the density requirement of the foam drilling fluid can be met.
In detail, the preparation of the foam drilling fluid is carried out in the slurry preparation tank 1, so that the field preparation is convenient to realize, and in the preparation process, a mixing device is required to carry out continuous mixing operation on the liquid in the slurry preparation tank 1 in the whole process. When the treating agent is added into the slurry preparation tank, the foam stabilizer (carboxymethyl starch, carboxyethyl starch and carboxymethyl cellulose) needs to be slowly added, and the foam stabilizer is continuously mixed after being added, so that the foam stabilizer can be fully dissolved in clear water, and a stable foaming environment is provided for a foaming agent to be added subsequently; then slowly adding a foaming agent (sodium dodecyl benzene sulfonate, trimethyl ethyl lactone and octadecanol) and a stabilizing agent, and continuously mixing until the foaming agent can be fully dissolved in water and fully foamed, wherein the foam can separate each bubble from each other under the action of the foam stabilizing agent and improve the stability of each bubble. The whole process requires mixing operation, so that the foaming is more complete, the foam stability is better, and the foam drilling fluid can be ensured to play a cooling role on the drill bit and have higher rock carrying capacity and the like.
In the foam drilling fluid, clear water is taken from the site, and the stabilizer is sodium bicarbonate, so that the material is convenient to obtain and the economical efficiency is good. In this embodiment, the stabilizer may also be sodium carbonate, and sodium bicarbonate can ionize hydrogen ions after being dissolved in water, so that the solution is weakly alkaline, and an environment suitable for foaming is provided for the foaming agent.
In the step S1, the mass ratio of the clear water to the treating agent to the stabilizing agent is (700-1300): (25-45): (0.5-2). Ensuring that the density and rheological index of the foam drilling fluid prepared according to the steps S1-S4 can be closer to the target value.
Further, in step S1, the mass ratio of carboxymethyl starch, carboxyethyl starch, carboxymethyl cellulose, sodium dodecylbenzene sulfonate, trimethylethyl lactone and stearyl alcohol in each component of the treating agent is: (9.8-10.2): (9.8-10.2): (4.8-5.2): (3.8-4.2): (5.8-6.2): (0.8 to 1.2). So that the foam stabilizing effect and the foaming effect are better. Meanwhile, in the step S1, the mass ratio of the clear water to the treating agent to the stabilizing agent is (700-1300): (25-45): (0.5-2), the density and rheological property indexes of the foam drilling fluid prepared according to the steps S1-S4 meet target values, and the adjusting times can be effectively reduced.
In the above formulation method, after step S4, the following steps may be further included:
s5: detecting whether the density and rheological index of the foam drilling fluid in the slurry preparation tank 1 reach target values;
if the density and rheological index reach the target value, the preparation of the foam drilling fluid is finished;
if the density and rheological index do not reach the target value, go to step S6;
s6: if the density is higher than the target value and the rheological index is lower than the target value, adding each treating agent into the slurry preparation tank 1 according to the mass ratio in the step S1;
and if the density is lower than the target value and the rheological index is higher than the target value, adding the clean water into the slurry preparation tank 1.
At this time, the preparation apparatus includes a detection device for detecting the density and rheological index of the foam drilling fluid, and specifically, no specific requirement is made on the setting of the detection device, and how to detect the density and rheological index of the foam drilling fluid by the detection device is well known to those skilled in the art, and is not described herein again for saving space.
The foam drilling fluid preliminarily prepared (prepared according to steps S1-S4) is detected, the density and rheological property requirements of the foam drilling fluid are different due to different field environments, step S5 determines whether the density and rheological property indexes of the foam drilling fluid reach respective target values (that is, the density reaches the density target value and the rheological property index reaches the rheological property index target value) according to the requirements of the current working condition, if the density and rheological property indexes reach the respective target values, the preparation of the foam drilling fluid is completed, and if the density and rheological property indexes of the foam drilling fluid do not reach the respective target values, the density and rheological property indexes of the foam drilling fluid are adjusted through step S6 until the density and rheological property indexes reach the respective target.
The addition of the clear water or each treating agent can be specifically adjusted according to different requirements. When the foam drilling fluid is prepared in a mining field, due to the fact that the requirements on the density range of the foam drilling fluid are different due to different reservoir types, the addition amount of the clear water and the treating agent can be adjusted according to specific working conditions on the field, so that the foam drilling fluid can be suitable for the reservoir layers of different types, and the applicability is good.
In the above examples, the target value of the density was 0.75g/cm3~1.00g/cm3(ii) a Target values for the rheological index include: an apparent viscosity of 15 to 35 mPas, a plastic viscosity of 8 to 25 mPas, a dynamic shear force of 10 to 25 mPas, and a dynamic plastic ratio of 0.6 to 1.0 Pa/(mPas). The foam drilling fluid with the density and rheological index reaching the target values can meet the requirements of different reservoirs under normal conditions.
In the above embodiment, as shown in fig. 2, in step S3, adding the foam stabilizer into the slurry preparation tank includes sequentially adding carboxymethyl starch, carboxyethyl starch, and carboxymethyl cellulose into the slurry preparation tank; in step S4, adding the foaming agent into the slurry preparation tank includes sequentially adding sodium dodecylbenzenesulfonate, trimethylethyllactone, and octadecanol into the slurry preparation tank. The adding sequence of the foam stabilizer and each foaming agent is limited, so that the foaming effect can be ensured to be more stable.
In the above embodiment, as shown in fig. 2, in step S3, after adding the foam stabilizer and continuously mixing for a first preset time, the process proceeds to step S4; in step S4, mixing is continued for a second predetermined time after the addition of the blowing agent. The setting of first preset time can guarantee that the foam stabilizer is fully dissolved in water to can provide a more stable foaming environment for the foaming of foamer, and the setting of second preset time can guarantee that each foamer can fully dissolve in water, and can foam completely, guarantee the foaming effect.
In the above embodiment, the first preset time and the second preset time are 20min to 30 min. The first preset time and the second preset time can be the same or different, no specific limitation is imposed on the time, and the mixing operation in 20-30 min can ensure that the foam stabilizer and the foaming agent can fully act to improve the foaming effect and the stability.
The mixing operation is not particularly limited in this embodiment, and the mixing operation is an agitation or circulation fluid operation in this embodiment. Correspondingly, the mixing means of the preparation apparatus are the stirring means 2 arranged in the slurry tank 1 when the mixing action is stirring, and the mixing means comprise a fluid pump 32 and a line 31 when the mixing action is circulating fluid action. The fluid pump 32 is arranged outside the slurry preparation tank 1, the pipeline 31 is communicated with the slurry preparation tank 1 and forms a circulating fluid loop, and the liquid in the circulating fluid loop can be circulated under the action of the fluid pump 32, that is, the fluid pump 32 can drive the liquid in the circulating fluid loop to circulate so as to mix the liquid in the slurry preparation tank 1. During the preparation process, the feeding device 4 can directly feed the inorganic salt and the clear water into the top opening of the slurry preparation tank 1, or the feeding device 4 feeds the inorganic salt and the clear water through a funnel 33 arranged on the pipeline 31.
In addition, when foam drilling fluid is prepared on site, the volume of the slurry preparation tank 1 is not less than 10m3So as to meet the requirements of site construction, and meanwhile, the existing slurry preparation tank 1 can be directly used without additional arrangement,the economy is good. If the mixing operation is stirring, the stirring speed of the stirring device 2 is not less than 70r/min, and if the mixing operation is a circulating fluid action, the discharge capacity of the fluid pump 32 is not less than 12m3H, so as to realize the sufficient mixing of the liquid in the slurry preparation tank 1.
The following is the density change condition of the foam drilling fluid after adjusting the addition amount of clear water or the treating agent in the process of preparing the foam drilling fluid by the preparation method and the preparation equipment.
Preparing foam drilling fluid, and adjusting the adding proportion of a foaming agent according to gradient, wherein the density of the point A is the following mass ratio of the components: the density of the foam drilling fluid prepared from 1000 parts of clean water, 10 parts of carboxymethyl starch, 10 parts of carboxyethyl starch, 5 parts of carboxymethyl cellulose, 4 parts of sodium dodecyl benzene sulfonate, 6 parts of trimethyl ethyl lactone, 1 part of octadecanol and 1 part of sodium bicarbonate is gradually increased at intervals of 0.25, 0.5 and 0.25, and B, C, D, E points are continuously recorded in total of 4 points, specifically, the mass ratio of the components is on the basis that the clean water is 1000 parts of clean water, 10 parts of carboxymethyl starch, 10 parts of carboxyethyl starch, 5 parts of carboxymethyl cellulose and 1 part of sodium bicarbonate are unchanged, and the foaming agent at the point B is 4.25 parts of sodium dodecyl benzene sulfonate, 6.5 parts of trimethyl ethyl lactone and 1.25 parts of octadecanol; the foaming agent at the point C is 4.5 parts of sodium dodecyl benzene sulfonate, 7 parts of trimethyl ethyl lactone and 1.5 parts of octadecanol; the foaming agent at the point D is 4.75 parts of sodium dodecyl benzene sulfonate, 7.5 parts of trimethyl ethyl lactone and 1.75 parts of octadecanol; the foaming agent at the point E is sodium dodecyl benzene sulfonate 5, trimethyl ethyl lactone 8 and octadecanol 2.
And measuring the density of the foam drilling fluid at the B point, the C point, the D point and the E point respectively by using a density scale, and comparing the density distribution of the foam drilling fluid at the 5 points, wherein the density distribution is shown in table 1.
TABLE 1 Density distribution of foam drilling fluids
And (II) preparing foam drilling fluid, regulating the addition amount of clear water according to gradient, gradually increasing the addition amount of the clear water at 50 intervals on the basis of the point A to dilute the foam drilling fluid at the point A, continuously recording F, G, H, J points (the addition amounts of the clear water are 1050, 1100, 1150 and 1200 in sequence), respectively measuring the density of the foam drilling fluid at the points F, G, H and J by using a density scale, and comparing the density distribution of the foam drilling fluid at the points 5, wherein the density distribution is shown in Table 2.
TABLE 2 Density distribution of foam drilling fluids
It can be seen that the density of 0.75-1.00 g/cm can be realized by adjusting the proportion of the solid-free foam drilling fluid treating agent3And (5) adjusting within the range. Specifically, as can be seen from table 1, the density of the foam drilling fluid can be reduced by increasing the proportion of the foaming agent in the foam drilling fluid; it can be seen from table 2 that the density of the foam drilling fluid can be increased by increasing the proportion of the clear water in the foam drilling fluid. And with the addition of the foaming agent, the density of the prepared foam drilling fluid is changed stably, and the foam drilling fluid with the target density is obtained through control.
In the preparation process of the foam drilling fluid, no solid-phase material is contained, so that the foam drilling fluid has small influence on the permeability of the stratum, the reservoir can be effectively protected, and the yield of the three gases cannot be influenced.
The following is a test of the pollution degree of the foam drilling fluid prepared by the preparation method and the preparation equipment in this embodiment to different core types (i.e. different reservoirs), wherein the core types include tight sandstone, coal bed and shale, and in the test, the different core types are set to be plungers with the size of 38mm × 70 mm. Referring to the national standard SY/T5336-1996, the driving pressure is set to be 2MPa, and the confining pressure is set to be 2.5 MPa. The original permeability of the core gas and the permeability of the gas contaminated with the foam drilling fluid in this example were measured with standard brine, respectively, and the permeability recovery after contamination was calculated, the results of which are shown in table 3.
TABLE 3 degree of contamination of different core types with foam drilling fluids
Therefore, after the foam drilling fluid provided by the embodiment pollutes three types of core plungers such as compact sandstone, coal bed and shale, the plunger permeability recovery rates are 91.67%, 93.55% and 84.21%, and the permeability recovery effect is ideal, which indicates that the foam drilling fluid has ideal leakage control effect for three types of reservoirs and has low pollution degree to the stratum.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.