While-drilling cementing wall-fixing agent as well as preparation method and application process thereof

Abstract

The invention discloses a cementing wall-fixing agent while drilling as well as a preparation method and an application process thereof, belongs to the technical field of oilfield chemistry, and particularly relates to preparation of the cementing wall-fixing agent while drilling. The preparation method of the while-drilling cementing wall-fixing agent comprises the step of uniformly mixing and stirring the thermoplastic resin, the curing agent and the inorganic powder according to the proportion at normal temperature and normal pressure. The wall-fixing agent material is simple and safe in production process, low in material cost and convenient for large-scale production and application, and the product can block pores, reduce the filter loss, bond sand shale strata and improve the pressure-bearing capacity of the strata, so that the aim of stabilizing the well wall is fulfilled. The invention further provides an application process of the while-drilling cementing wall-fixing agent. The application process comprises an applicable drilling fluid system and dosage and construction processes under different formation porosities and different working conditions.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry and drilling fluid, and in particular to a drilling-while-cementing wall-fixing agent and a preparation method and application process thereof. Background Art

[0002] During the drilling process of sandstone and mudstone, especially when drilling in long open hole and multi-pressure system formations, wellbore instability is very likely to occur. For example, the Qianfoya Formation in the continental tectonic belt of the Puguang gas field is mainly composed of interbedded sandstone and mudstone, with multiple pressure systems in the vertical direction. The collapse pressure of the continental formation is high, and the drilling fluid density designed according to the formation pore pressure is difficult to maintain the stability of the wellbore. The drilling fluid safety density window is narrow or even negative, and leakage and collapse occur frequently during the drilling process. According to statistics, the five wells constructed by Sinopec Zhongyuan Petroleum Engineering Co., Ltd. in 2022 with Qianfoya mudstone as the target layer in this block all suffered serious collapse in the horizontal section, of which two wells were stuck due to collapse, and the leakage problem has become the main bottleneck problem restricting the development of this block. At present, most wall fixers improve the stability of the near-wellbore formation by plugging micropores, reducing the entry of filtrate into the formation or inhibiting the hydration of mudstone, but it is difficult to solve the collapse problem of sandstone and mudstone formations with long open hole and multi-pressure systems. Therefore, it is necessary to use wall consolidation technology to improve the cementing capacity of sandstone and mudstone, so as to achieve the purpose of stabilizing the formation and optimizing and speeding up drilling.

[0003] Some wall-fixing agents have been developed in the industry, such as the Chinese patent document with publication number CN114075065A, which discloses a chemical wall-fixing agent for broken formations and its preparation method, application and advance injection construction method. The chemical wall-fixing agent is composed of slag, bentonite, water glass, gypsum, ultrafine calcite and water. The wall-fixing agent is driven into the formation before the broken zone is uncovered, and after solidification after standing for 4h to 16h, the plugging drilling is carried out; this type of wall-fixing agent requires stopping the drilling operation and does not belong to the wall-fixing while drilling.

[0004] In the wall fixing technology while drilling, the Chinese patent document with application number 202010681904.0 provides a wall fixing agent for drilling fluid and its preparation method and application. The wall fixing agent is synthesized from acrylamide, dimethyldiallylammonium chloride, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid and other raw materials in proportion. The material is added to the water-based drilling fluid to enhance the cohesion and adhesion between rock particles, thereby achieving the purpose of improving the rock strength of the well wall and fixing the wall to prevent collapse. The Chinese patent document with application number 202210826056.7 provides a wall solidifier and its preparation method and application. The wall solidifier is composed of dispersed latex powder, rubber, thermosetting resin, epoxy resin, chloroprene latex and nano-silicon dioxide in proportion, wherein the thermosetting resin undergoes a thermosetting reaction under the action of formation temperature and drilling pressure difference, consolidates the formation micro-cracks and micro-pores, thereby improving the strength of the well wall rock, and is used in combination with dispersed latex powder, rubber, epoxy resin, chloroprene latex and nano-silicon dioxide to further strengthen the well wall, improve the pressure bearing capacity of the well wall, and achieve the effect of anti-collapse. In its preparation process, the thermosetting resin, epoxy resin and chloroprene latex need to be mixed in a solvent at 100℃~150℃, and then mixed with dispersed latex powder and nano-silicon dioxide for 1~3h and a mixing temperature of 180℃~220℃.

[0005] The above-mentioned wall-fixing agent can be used while drilling, but its composition is complex, its preparation method is complicated, its production cost is high, and it is not conducive to its wide promotion and application. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a drilling-while cementing and wall-fixing agent and a preparation method and an application process thereof. The wall-fixing agent can cement sandstone and mudstone, thereby improving the pressure-bearing capacity of the formation and stabilizing the formation, and can effectively prevent the collapse of the sandstone and mudstone formations. The preparation is simple and the drilling-while application can fundamentally solve the problem of well wall instability and avoid the occurrence of complex phenomena such as drill sticking and collapse caused by well wall instability.

[0007] One object of the present invention is to provide a drilling cementing and wall fixing agent, which is made of the following raw materials in parts by weight:

[0008] 35 to 65 parts of thermoplastic resin, 5 to 15 parts of curing agent and 25 to 65 parts of inorganic powder; the inorganic powder is calcium carbonate and silicon dioxide;

[0009] The thermoplastic resin is one or more of thermoplastic phenolic resin, thermoplastic urea-formaldehyde resin, thermoplastic epoxy resin and thermoplastic melamine resin; the curing agent is one or two of hexamethylenetetramine, polyamide and oxalic acid.

[0010] The wall-fixing agent material product provided by the present invention can not only block pores and reduce filtration loss, but also cement sandstone and mudstone formations to improve the pressure bearing capacity of the formations, thereby achieving the purpose of stabilizing the well wall. The production process of the product is simple and safe, the material cost is low, and it is convenient for large-scale production and application.

[0011] In an embodiment of the present invention, the particle size of the inorganic powder is 10 to 1000 nm.

[0012] In an embodiment of the present invention, the calcium carbonate is nanometer-level calcium carbonate, and the silicon dioxide particle size is nanometer-level.

[0013] In an embodiment of the present invention, the drilling cementing and wall fixing agent is made of the following raw materials in parts by weight: 45 to 60 parts of thermoplastic resin, 8 to 12 parts of curing agent and 35 to 50 parts of inorganic powder.

[0014] The present invention provides a method for preparing a drilling cementing and wall-fixing agent, comprising:

[0015] Mixing 35 to 65 parts by weight of a thermoplastic resin, 5 to 15 parts by weight of a curing agent, and 25 to 65 parts by weight of an inorganic powder to obtain a while-drilling cementing and wall-fixing agent;

[0016] The inorganic powder is calcium carbonate and silicon dioxide; the thermoplastic resin is one or more of thermoplastic phenolic resin, thermoplastic urea-formaldehyde resin, thermoplastic epoxy resin and thermoplastic melamine resin; the curing agent is one or two of hexamethylenetetramine, polyamide and oxalic acid.

[0017] In the embodiment of the present invention, the thermoplastic resin, the curing agent, the calcium carbonate and the silicon dioxide can be mixed in proportion at room temperature and pressure, and the mixture is evenly mixed to obtain the wall-fixing agent product.

[0018] In the raw materials for preparing the drilling cementing and wall fixing agent described in the present invention, the weight proportion of the thermoplastic resin is 35 to 65 parts, preferably 45 to 60 parts. The thermoplastic resin described in the present invention is one or more of thermoplastic phenolic resin, thermoplastic urea-formaldehyde resin, thermoplastic epoxy resin, and thermoplastic melamine resin, preferably thermoplastic phenolic resin and / or thermoplastic epoxy resin. The thermoplastic resin described in the present invention is powdery at room temperature and pressure, and its molecular structure is mainly linear, has the properties of softening by heat and hardening by cooling, and can be solidified. Particularly preferably, the degree of polymerization of the thermoplastic phenolic resin is 4 to 12, and the thermoplastic epoxy resin is E42 type. The present invention has no special restrictions on the source of the thermoplastic resin, and commercially available products well known to those skilled in the art can be used.

[0019] In the present invention, the weight proportion of the curing agent is 5 to 15 parts, preferably 8 to 12 parts. The curing agent of the present invention is one or two of hexamethylenetetramine, polyamide, and oxalic acid, preferably hexamethylenetetramine and / or polyamide. For example, the polyamide is one of DJ2421H, DJ2323, DJ2428, and DJ2431 produced by Shandong Deyuan Epoxy Technology Co., Ltd. In the present invention, the type and amount of the curing agent determine the curing temperature and the curing strength. The curing temperature of the present invention is generally 80°C to 150°C. The present invention has no special restrictions on the source of the curing agent, and commercially available products well known to those skilled in the art can be used.

[0020] In addition, the inorganic powders used to prepare the cementing and wall-fixing agent while drilling are calcium carbonate and silicon dioxide; the particle sizes of the calcium carbonate and silicon dioxide can be adjusted according to the formation conditions, and the particle sizes are preferably 10 to 1000 nm. For example, nanometer-level calcium carbonate and nanometer silicon dioxide can be used.

[0021] In the raw materials of the drilling cementing agent of the present invention, the total mass fraction of calcium carbonate and silicon dioxide is 25 to 65 parts, preferably 35 to 50 parts. In the present invention, the calcium carbonate and silicon dioxide can block the pores of sandstone and mudstone, which can not only reduce filtration and strengthen the well wall, but also reduce the cost of the product. The present invention has no special restrictions on the proportion and source of the calcium carbonate and silicon dioxide, and commercial products familiar to those skilled in the art can be used; the mass ratio of nano-micron calcium carbonate to nano-silicon dioxide can be 1 to 2: 2.2.

[0022] In the present invention, the drilling cementing wall-fixing agent enters the pores or microcracks of shale and sandstone formations as the newly uncovered formation or the drilling pressure difference acts, and calcium carbonate and silicon dioxide bridge the narrow pores or cracks to form a plugging layer. The thermoplastic resin softens under the action of the formation temperature, and then undergoes polymerization reaction with the curing agent to solidify, further filling, accumulating and cementing the formation microcracks, micropores and the plugging layer, thereby improving the rock strength of the formation near the wellbore wall, and the formed filter cake is denser, which can effectively prevent the drilling fluid and its filtrate from invading the formation, strengthen the wellbore wall through the synergistic effect of plugging and cementing, improve the pressure bearing capacity of the wellbore wall, and have a good anti-collapse effect.

[0023] Another object of the embodiment of the present invention is to provide an application process of a while-drilling cementing and wall-fixing agent, which uses the while-drilling cementing and wall-fixing agent described above to perform while-drilling wall fixing and while-drilling segment plug wall fixing.

[0024] The application process of the embodiment of the present invention consists of a while-drilling wall fixing application process and a while-drilling segment plug wall fixing application process; wherein, the while-drilling wall fixing application process is realized by the following technical measures: 50 to 100 meters before drilling into an easily unstable sandstone and mudstone formation, the drilling fluid properties are adjusted and a specified amount of the while-drilling cementing wall fixing agent is added according to the drilling fluid system and formation characteristics.

[0025] In an embodiment of the present invention, the drilling fluid system is a salt water drilling fluid system or an oil-based drilling fluid system, preferably a drilling fluid system containing 15wt% to saturated sodium chloride (NaCl), a white oil-based drilling fluid system or a diesel-based drilling fluid system; the density of the drilling fluid system is preferably 1.1g / cm 3 ~1.8g / cm 3 .

[0026] In the embodiment of the present invention, the amount of the drilling wall-fixing agent added according to the drilling fluid system and the formation characteristics is 3% to 10% of the volume of the drilling fluid. 3 3% is added to the drilling fluid, that is, 3t of drilling cementing agent is added (the same below). More preferably, at 1.1g / cm 3 ~1.3g / cm 3 The addition amount under the drilling fluid density is 3%; at 1.3g / cm 3 ~1.6g / cm 3 Drilling fluid density, and leakage rate <5m 3 / h in the formation, the dosage is 5%, at a leakage rate of 5m 3 / h~10m 3 / h The dosage in the formation is 7%; at 1.6g / cm 3 ~1.8g / cm 3 Drilling fluid density, and permeability loss and leakage rate <5m 3 / h in the formation, the dosage is 7%, at a leakage rate of 5m 3 / h~10m 3 / h The amount added in the formation is 10%; when drilling to the lower formation with high pressure coefficient but the formation pressure bearing capacity needs to be improved, or the sand and mudstone formation prone to collapse, the leakage rate is 10m 3 / h~15m 3 The addition amount in the formation is 10% / h.

[0027] In the embodiment of the present invention, the drilling plug wall reinforcement application process is realized by the following technical measures: when the density of drilling fluid needs to be increased in the shale that is easy to leak and collapse, 3% to 5% drilling cementing and wall reinforcement agent is first added to the whole well, and then the displacement is increased to 1 to 1.5 times the normal circulation to flush the well wall, clean the wellbore, and check for leaks. After the drilling fluid circulates evenly and there is no leakage, the displacement is reduced to 0.6 to 0.8 times the normal density, and the density per cycle is controlled not to exceed 0.02g / cm 3, every increase of 0.06g / cm 3 , cycle for one week, use the density-enhancing pressure difference to gradually densify the mud cake, cement the formation, and stabilize the wellbore wall, so that the formation gradually adapts to the change of wellbore pressure; repeat the above steps until the density is increased to the designed value;

[0028] When drilling into the stratum with collapse and leakage (leakage rate 10m 3 / h~15m 3 / h), pump in a certain volume of high-concentration wall-fixing slug while drilling (hereinafter referred to as slug), increase the displacement to 1 to 1.5 times of normal before the slug is out of the water surface of the drill bit; after pumping and replacement, pull out the drill to 100m to 150m above the slug, gradually increase the displacement to 1 to 1.5 times of normal according to the downhole conditions, circulate for 2 weeks, drill down to the bottom of the well in sections, reduce the displacement (with no leakage as the standard), and try drilling with high-concentration slugs. If the downhole is normal, resume drilling at normal displacement after 1d to 2d; if it is still abnormal, increase the concentration of wall-fixing slug while drilling, and repeat the injection of slugs; after drilling through the unstable formation, use short trips and high-displacement cycles to destroy the well wall retention layer and the virtual mud cake, and then pump in the slug again to improve the formation stability.

[0029] In the solution of the above embodiment, the formula of the high-concentration while-drilling segment plug wall-fixing slurry is: well slurry + 8% to 15% while-drilling cementing and wall-fixing agent.

[0030] In addition, the pumping volume of the high-concentration segment plug wall-fixing slurry pumped into a certain volume is: the volume of the unstable formation wellbore plus 3m 3 ~5m 3 .

[0031] Compared with the prior art, the beneficial effects of the present invention include: the drilling cementing and wall-fixing agent provided by the present invention can seal the well wall while drilling, without the need to pull the drill bit, and the construction process is simple, and it is applicable to salt water drilling fluid systems and oil-based drilling fluid systems, and is applicable to a wide range of drilling fluid systems. The drilling cementing and wall-fixing agent provided by the present invention can cement sandstone and mudstone formations, improve the pressure bearing capacity of the formation, and reduce the filtration loss through the sealing and coordination effect of calcium carbonate and silicon dioxide, improve the stability of the well wall, and improve the safety and efficiency of the drilling project. The wall-fixing agent product has abundant raw materials, and the composition and preparation process are simple, safe, and low-cost, which is convenient for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a comparison diagram of 4# and 6# mud cakes in the embodiment of the present invention;

[0033] Figure 2 This is a graph for evaluating the bonding and wall consolidation performance in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical content disclosed in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The embodiment of the present invention discloses a drilling cementing wall fixing agent with simple operation and low cost, and a preparation method and application process thereof. The technology can solve the problem of well wall instability in sandstone and mudstone long open hole multi-pressure system formations, cement sandstone and mudstone, improve the pressure bearing capacity of the formation, operate safely and efficiently, have good economic benefits, and are suitable for promotion.

[0036] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0037] In the following examples and comparative examples, the thermoplastic resin used is in powder form at room temperature and pressure, wherein the degree of polymerization of the thermoplastic phenolic resin is 4 to 12, the thermoplastic epoxy resin is E42 type; the nano-micron calcium carbonate particle size is 150 to 1000 nm, the nano-silicon dioxide particle size is 20 to 60 nm; and the polyamide is DJ2421H type. There is no particular restriction on the sources of the above raw materials, and commercially available products known to those skilled in the art can be used.

[0038] Example 1

[0039] 60kg of thermoplastic phenolic resin, 10kg of hexamethylenetetramine, 20kg of nano-micron calcium carbonate and 10kg of nano silicon dioxide are uniformly mixed together to prepare the wall-fixing agent.

[0040] Example 2

[0041] 50 kg of thermoplastic epoxy resin, 8 kg of polyamide, 20 kg of nano-micron calcium carbonate and 22 kg of nano silicon dioxide are uniformly mixed together to prepare the wall-fixing agent.

[0042] Example 3

[0043] 45kg of thermoplastic phenolic resin, 10kg of thermoplastic epoxy resin, 5kg of polyamide, 10kg of hexamethylenetetramine, 10kg of nano-micron calcium carbonate and 20kg of nano silicon dioxide are uniformly mixed together to prepare the wall-fixing agent.

[0044] Comparative Example 1

[0045] 50 kg of nano-micron calcium carbonate and 50 kg of nano-silicon dioxide are uniformly mixed together to obtain inorganic powder.

[0046] Comparative Example 2

[0047] 80 kg of thermoplastic phenolic resin and 20 kg of hexamethylenetetramine were uniformly mixed together to obtain a resin material.

[0048] Comparative Example 3

[0049] 60 kg of thermoplastic phenolic resin, 20 kg of thermoplastic epoxy resin, 5 kg of polyamide, and 15 kg of hexamethylenetetramine were uniformly mixed together to obtain a resin material.

[0050] Performance Evaluation

[0051] The LV-CMC used is low-viscosity carboxymethyl cellulose sodium salt, purchased from Hengda Hydrophilic Colloid Taizhou Co., Ltd.; SMP is sulfomethyl phenolic resin for drilling fluid, purchased from Henan Desheng Drilling Fluid Technology Co., Ltd.; SMC is sulfonated lignite, purchased from Shandong Zhengyang New Material Technology Co., Ltd.; NaOH is sodium hydroxide, purchased from Nanyang Boya Fine Chemical Co., Ltd.; the density of barite is 4.2 g / cm 3 , purchased from Henan Aotai Chemical Co., Ltd.; CaO is calcium oxide, purchased from Puyang Zhongyuan Sanli Industrial Co., Ltd.; bentonite was purchased from Lingshou County Yuchuan Mineral Products Co., Ltd.; CaCl 2 It is calcium chloride purchased from Puyang Jintai Chemical Co., Ltd.; the integrated emulsifier and oil-based drilling fluid asphalt resin fluid loss reducer are provided by the Drilling Engineering Technology Research Institute of Zhongyuan Petroleum Engineering Co., Ltd.

[0052] (1) Plugging performance evaluation

[0053] Evaluation method: The salt water drilling fluid is prepared and evaluated with reference to GBT 16783.1-2014 Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 1 Water-based Drilling Fluids, and the oil-based drilling fluid is prepared and evaluated with reference to GBT 16783.2-2012 Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 2 Oil-based Drilling Fluids.

[0054] According to the formula shown in Table 1, the compatibility and plugging performance of the drilling cementing and wall fixing agent in different density brine drilling fluids and oil-based drilling fluids were investigated. The results showed that after adding the drilling cementing and wall fixing agent of the present invention, the apparent viscosity AV, plastic viscosity PV, and dynamic shear force YP of the drilling fluid did not change significantly, indicating that the drilling cementing and wall fixing agent has good compatibility with the drilling fluid and meets the requirements of drilling.

[0055] Compared with the comparative examples, namely, No. 1#, 2#, 4#, 5#, 7#, and 8#, after adding the drilling cementing agent (No. 3#, 6#, and 9#), the high temperature and high pressure fluid loss (HTHP120℃ ) is greatly reduced, and the density of the mud cake is significantly improved (see Figure 1 ); The improvement of plugging performance is beneficial to reduce the amount of filtrate entering the formation and maintain the stability of shale. Figure 1 In the figure, the left side is 4# mud cake, and the right side is 6# mud cake, which has higher density.

[0056] Table 1 Effect of sealing agent dosage on drilling fluid performance

[0057]

[0058] Salt water drilling fluid formula: 4% bentonite + 0.3% LV-CMC + 4% SMP + 4% SMC + 0.3% NaOH + 15% NaCl + barite;

[0059] Oil-based drilling fluid formula: 240mL 0 # Diesel + 4% integrated emulsifier + 60gCaCl 2 Aqueous solution + 2% CaO + 1% oil-based drilling fluid asphalt resin filtrate reducer + barite.

[0060] (2) Evaluation of the bonding and wall consolidation capacity of different types of leaky layers

[0061] Evaluation method: Use river sand of different particle sizes to simulate the leaking layer, among which 60-90 mesh sand simulates permeability leakage, that is, leakage rate <5m 3 / h; 40-60 mesh sand simulates small leakage, i.e. leakage rate 5-10m 3 / h; 20-40 mesh sand simulates medium leakage, i.e. leakage rate of 10-15m 3 / h; at 1.5g / cm 3 5% of Example 1 and 5% of Comparative Example 1 were added to the brine drilling fluid to obtain experimental sample slurry, and its cementing and wall-fixing performance was examined. On a 71-type high-temperature and high-pressure filter loss instrument, a filter screen was first placed in the filter press, and then 100g of river sand of different particle sizes was added, and the surface was filled as flat as possible, and then the experimental sample slurry was slowly and evenly added along the wall of the instrument, and cured at 100°C / 4.2MPa for 30 minutes to examine its cementing performance of river sand of different particle sizes.

[0062] The results show that after adding the comparative example 1, the sands of different particle sizes are in a loose state and have no cementing effect. Adding the drilling cementing and wall fixing agent of Example 1 can cement the loose sands of different particle sizes of 20 to 90 meshes into a whole, and have a certain compressive strength. Figure 2 . Figure 2 The cementation and wall consolidation conditions are 60-90 mesh, 40-60 mesh, and 20-40 mesh, respectively.

[0063] (3) Comprehensive performance evaluation

[0064] Evaluation method: On the visual medium-pressure sand bed filter loss meter, put 40-60 mesh sand into the drilling fluid cup to the 350mL scale line, slowly pour in 200mL of the sample slurry shown in Table 2, tighten the cup cover, connect the air source, slowly adjust the pressure to 0.7MPa, open the air valve, keep it for 30 minutes, measure the volume of the filtrate in the measuring cylinder, or read and record the depth of the filtrate invading the sand layer. After the first step of the experiment is completed, the filtrate invading the sand layer is taken out and sealed and placed in a 90℃ water bath for curing for 24h and 72h, taken out and cooled to room temperature, and the servo pressure testing machine is used to test the cementation strength.

[0065] The results in Table 2 show that No. 5, No. 6, No. 7 # It is a physical plugging material with a single inorganic component, with low pressure bearing capacity, large leakage, and no bonding ability; No. 8# and 9# are single-component resin and curing agent, with weak plugging ability, and a certain improvement in bonding ability but the extent is limited. Considering that their prices generally exceed 15,000 yuan / ton, the overall economic benefits are poor.

[0066] After adding the drilling cementing and wall-fixing agent of the embodiment of the present invention, the pressure-bearing capacity and filtrate-invasion prevention capacity of the sand bed are significantly improved due to the synergistic effect of multiple components. At the same time, a cementing and curing reaction occurs after the filtrate invades the sand layer, and the reaction continues over time. This feature is conducive to gradually strengthening the well wall, improving the pressure-bearing capacity of the formation, and creating powerful conditions for later density increase, cementing, etc.

[0067] Table 2 Comparative evaluation table of plugging and wall solidification performance

[0068]

[0069] Salt water drilling fluid formula: 4% bentonite + 0.3% LV-CMC + 4% SMP + 4% SMC + 0.3% NaOH + 15% NaCl + barite.

[0070] The above experiments show that the drilling cementing and wall-solidifying agent in the embodiment of the present invention has a synergistic effect of plugging and cementing, which is beneficial to stabilizing the well wall and improving the pressure bearing capacity of the formation, solving the problem of well wall instability in sandstone and mudstone formations, and especially can solve the problem of drilling fluid density designed according to the formation pore pressure in long open hole and multi-pressure system formations, and it is difficult to maintain the stability of the well wall.

[0071] Application Example 1

[0072] TSX Well is a pre-exploration well deployed by CNPC on the southeast slope of the Sichuan Central Paleo-uplift in the Sichuan Basin. The target layer is the Maokou Formation. The designed well depth is 4688m. The second opening 311.2mm well section adopts 1.5g / cm 3 The composite salt drilling fluid uncovers the artesian well, which is mainly composed of sand and mudstone. The formation has low pressure, developed micro-cracks, and is easy to induce opening and leakage; the lower part needs to increase the density to 1.6g / cm 3Only in this way can the gypsum layer on the Leikou slope be balanced and the gas layer be stabilized, and the contradiction between leakage and overflow be prominent.

[0073] In order to solve this complex situation, a combination of drilling-while-drilling and drilling-while-plugging wall reinforcement is adopted. The specific implementation method is as follows: At 1450m (52m from the artesian well), 5% of the drilling-while-drilling cementing agent described in Example 1 is added once according to the well slurry volume to improve the pressure bearing capacity of the formation and widen the safe density window. After drilling through the artesian well group without leakage, the drilling-while-plugging wall reinforcement process (well slurry + 10% drilling-while-drilling cementing agent) is used to consolidate the well wall and improve the pressure bearing capacity of the formation. Then, the density is gradually increased to 1.6g / cm according to the drilling-while-plugging wall reinforcement process. 3 , and maintained this density until the drilling was completed at 2921m, with no leakage or overflow in the well. Compared with the adjacent well TSX, due to the narrow safety density window, the loss of drilling fluid in dealing with leakage and overflow was 1380.45m 3 , it took 23.28 days, and the application effect was significant.

[0074] Application Example 2

[0075] HYX-XHF Well is a shale gas horizontal well deployed by Sinopec in the Jiannan structure in the middle of the Shizhu complex syncline in the high and steep fold belt in eastern Sichuan Basin. It is a key evaluation well with a designed well depth of 5520m. The target layer Wujiaping is black siliceous mudstone with local cracks and high degree of fragmentation. The well was opened for three times with a 215.9mm borehole and a density of 1.45g / cm 3 The oil-based drilling fluid leaked at 4100m, with a leak rate of 10m 3 / h. After multiple plugging, the effect was not ideal. In order to reduce the leakage, the density was reduced to 1.40g / cm 3 , add 6% while drilling plugging agent to resume drilling, because the drilling fluid density window is narrow, it is impossible to maintain the stability of the wellbore by increasing the density (the density of the adjacent well is 1.47g / cm 3 In order to prevent the block from falling, the block falling in the 4200-4345m section of the well increased gradually during the subsequent drilling process, making it impossible to carry out normal construction.

[0076] To this end, the drilling plug wall reinforcement process was adopted, and 5% of the drilling cementing wall reinforcement agent described in Example 3 was added, and the density was gradually increased to 1.47 g / cm according to the process requirements. 3 After one week of circulation, no leakage was observed in the wellbore, and no new blocks were lost after the circulation and cleaning of the wellbore. The content of cementitious wall fixer while drilling was maintained at 5% in the whole well slurry, and the density was maintained until 5435m was completed. No leakage or well collapse occurred. The completion electrical measurement showed that the average wellbore expansion rate of the 4200m-4354m section was 15.26%, and the average wellbore expansion rate of the 4355m-5434m section was 6.32%, and the anti-collapse effect was good. At the same time, after adding the cementitious wall fixer while drilling, the loss of oil-based drilling fluid was reduced from 0.12m 3 / m down to 0.075m3 / m, significantly reducing filtration loss performance.

[0077] It can be seen from the above embodiments that the preparation method of the drilling cementing and wall fixing agent provided by the present invention can be: mixing thermoplastic resin, curing agent, and inorganic powder in proportion and evenly at room temperature and pressure. The present invention also provides an application process of the drilling cementing and wall fixing agent, including: a suitable drilling fluid system and dosage and construction process under different formation porosities and different working conditions. The material composition and production process of the drilling cementing and wall fixing agent are simple and safe, the material cost is low, and it is convenient for large-scale production and application; the product can not only seal pores and reduce filtration loss, but also cement sandstone and mudstone formations and improve the pressure bearing capacity of the formation, thereby achieving the purpose of stabilizing the well wall and facilitating on-site application.

[0078] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A drilling cementing and wall consolidating agent, characterized in that: Made from the following raw materials in parts by weight: 35 to 65 parts of thermoplastic resin, 5 to 15 parts of curing agent and 25 to 65 parts of inorganic powder; the inorganic powder is calcium carbonate and silicon dioxide; The thermoplastic resin is one or more of thermoplastic phenolic resin, thermoplastic urea-formaldehyde resin, thermoplastic epoxy resin and thermoplastic melamine resin; the curing agent is one or two of hexamethylenetetramine, polyamide and oxalic acid.

2. The drilling cementing and wall fixing agent according to claim 1, characterized in that: The particle size of the inorganic powder is 10 to 1000 nm.

3. The drilling cementing and wall fixing agent according to claim 2, characterized in that: The calcium carbonate is nanometer-level calcium carbonate, and the silicon dioxide particle size is nanometer-level.

4. The drilling cementing and wall fixing agent according to any one of claims 1 to 3, characterized in that: The invention is prepared from the following raw materials in parts by weight: 45 to 60 parts of thermoplastic resin, 8 to 12 parts of curing agent and 35 to 50 parts of inorganic powder.

5. A method for preparing a drilling cementing and wall-fixing agent, characterized in that: include: Mixing 35 to 65 parts by weight of a thermoplastic resin, 5 to 15 parts by weight of a curing agent, and 25 to 65 parts by weight of an inorganic powder to obtain a while-drilling cementing and wall-fixing agent; The inorganic powder is calcium carbonate and silicon dioxide; the thermoplastic resin is one or more of thermoplastic phenolic resin, thermoplastic urea-formaldehyde resin, thermoplastic epoxy resin and thermoplastic melamine resin; the curing agent is one or two of hexamethylenetetramine, polyamide and oxalic acid.

6. An application process of a drilling cementing and wall fixing agent, characterized in that: The drilling-while-cementing wall-fixing agent according to any one of claims 1 to 4 is used to carry out drilling-while-cementing wall-fixing and drilling-while-segment-plugging wall-fixing.

7. The application process according to claim 6, characterized in that: The drilling-while-cementing wall application process comprises: adjusting the drilling fluid properties and adding a prescribed amount of the drilling-while-cementing wall-fixing agent according to the drilling fluid system and formation characteristics 50 to 100 meters before encountering an easily unstable sandstone shale formation.

8. The application process according to claim 7, characterized in that: The drilling fluid system is a salt water drilling fluid system or an oil-based drilling fluid system, preferably a drilling fluid system containing 15% to saturated NaCl, a white oil-based drilling fluid system or a diesel-based drilling fluid system; the density of the drilling fluid system is preferably 1.1 g / cm 3 ~1.8g / cm 3 .

9. The application process according to claim 7, characterized in that: The amount of the drilling wall-fixing agent added according to the drilling fluid system and the formation characteristics is 3% to 10%.

10. The application process according to claim 6, characterized in that: The drilling-while-drilling segment plug wall reinforcement application process includes: When drilling in shale that is prone to leakage or collapse and needs to increase the density of drilling fluid, first add 3% to 5% of drilling cementing agent to the whole well, then increase the displacement to 1 to 1.5 times the normal volume to circulate and flush the well wall, clean the wellbore, and check for leaks. After the drilling fluid circulates evenly and there is no leakage, reduce the displacement to 0.6 to 0.8 times the normal volume to increase the density, and control the density increase per cycle to not exceed 0.02 g / cm 3 , every increase of 0.06g / cm 3 , cycle for one week, use the density-enhancing pressure difference to gradually densify the mud cake, cement the formation, and stabilize the wellbore wall, so that the formation gradually adapts to the change of wellbore pressure; repeat the above steps until the density is increased to the designed value; When encountering a formation with both collapse and leakage, a certain volume of high-concentration segment plug wall-fixing slurry is pumped in. When the segment plug is out of the drill bit water surface, the displacement is increased to 1 to 1.5 times the normal value. After pumping and replacement, the drill is pulled up to 100m to 150m above the segment plug. According to the downhole conditions, the displacement is gradually increased to 1 to 1.5 times the normal value and circulated for 2 weeks. The drill is lowered to the bottom of the well in sections, and the displacement is reduced to try drilling with a high-concentration segment plug. If the downhole is normal, the normal displacement is restored after 1 to 2 days. If it is still abnormal, the concentration of the segment plug wall-fixing slurry is increased and the segment plug is repeatedly injected. After drilling through the unstable formation, the well wall retention layer and the false mud cake are destroyed by short tripping and large displacement circulation, and then the segment plug is pumped in again to consolidate the well wall and improve the formation stability.

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