Ultra-deep horizontal directional hole set hole fixing and wall protecting method under complex geological conditions

Abstract

The invention discloses an ultra-deep horizontal directional hole set hole fixing and wall protecting method under complex geological conditions, which comprises the following steps of: performing stratum section division on a target area by combining geological and geophysical prospecting data analysis of the target area; selecting a proper drilling structure and a drilling tool combination scheme based on division results of different stratum sections; and sequentially drilling the sections, selecting a proper wall protection scheme to fix the hole wall by combining the current stratum condition and the construction working condition before the drilling of the current section reaches the preset position, and after the drilling of the current section reaches the preset position, putting a sleeve to permanently stabilize the hole wall and isolate the drilling of the current section, and then drilling the next section. A set of complete horizontal hole wall protecting technical system is established by combining a drilling process of the horizontal directional hole, a wall protecting and hole fixing method and novel slurry material synthesis, so that the wall protecting effect of the ultra-deep horizontal directional hole under complex geological conditions can be met, and smooth drilling is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of engineering geological exploration, and in particular to a complete set of hole fixing and wall protection method for ultra-deep horizontal directional holes under complex geological conditions. Background Art

[0002] For engineering construction in complex and dangerous mountainous areas and high-altitude and cold mountainous areas, engineering geological surveys face difficult terrain, complex geology, fragile ecology, and harsh environment. Most existing engineering geological surveys use vertical hole drilling and coring methods, which have poor efficiency, low accuracy, shallow depth, and many blind spots, making it difficult to identify engineering geological conditions. As a result, the geological data provided to the design is not detailed enough, which brings great geological risks to major engineering construction. Therefore, it is urgent to carry out horizontal directional hole exploration methods to identify the geological and hydrological conditions along the route.

[0003] Horizontal directional borehole exploration, as a new exploration method in engineering geological exploration, has been introduced into geological exploration in complex and dangerous mountainous areas and high-altitude and cold mountainous areas on the plateau. However, the geological conditions in the complex and dangerous mountainous areas and high-altitude and cold mountainous areas in western my country are extremely complex, with well-developed structures and extremely complex geological conditions. The horizontal directional boreholes, especially the ultra-deep horizontal directional boreholes, cannot be successfully completed due to in-hole accidents such as slurry leakage, hole collapse, drill burial, and drill jamming. There is no complete and effective method for fixing the hole and protecting the wall in the prior art to solve the problem of instability of the well wall of the horizontal directional borehole. Specifically, the prior art mainly has the following problems:

[0004] (1) Existing horizontal hole cementing methods are mostly continuations of vertical hole cementing methods. However, due to the essential differences in the stress states of horizontal holes and vertical holes, the application effect of conventional wall protection methods in horizontal directional holes is minimal.

[0005] (2) The commonly used method at present is cementing the hole. However, since the vertical height difference of the horizontal directional hole is very small or zero, the radial diffusion range of the cement after entering the hole is very small, and the bonding and solidification of the upper part of the hole wall only stays on the surface, which makes it difficult to achieve the effect of stabilizing the hole wall.

[0006] (3) When cement is used to fix the hole, since the rock strength of the broken zone is lower than the strength of the cement after solidification, when scanning the hole, the drill bit is very likely to move in the direction of the rock strength being lower, which can easily cause the drilling trajectory to deviate and the azimuth and inclination to change.

[0007] (4) Casing is the most effective way to fix the hole and protect the wall. However, in horizontal directional holes under complex geological conditions, due to the continuous falling of blocks and collapse of the hole wall, the casing is thin in wall and can only withstand a small torque, so it is impossible to sweep the hole down to the deep part. It is also impossible to effectively isolate the deep hole wall and achieve the purpose of fixing the hole and protecting the wall.

[0008] In short, the existing technology mainly relies on cement grouting and casing wall protection, but the horizontal directional hole has almost no vertical height difference, and the cement slurry cannot diffuse radially. It will only solidify the middle and lower parts of the hole wall, and the upper part of the hole wall still cannot be consolidated into a broken loose layer, and still collapses. On the other hand, the casing wall protection can play a permanent wall protection role, but due to the equipment, pipes, processes, and aperture size of the geological exploration hole, the number of casing levels is often limited. In most cases, it can only isolate the loose broken zone in the shallow part, and the deep and ultra-deep broken zones cannot be reached and the isolation and protection of the hole cannot be achieved. Summary of the invention

[0009] The present application provides a complete set of hole fixing and wall protection methods for ultra-deep horizontal directional holes under complex geological conditions, so as to solve the problem of horizontal directional hole wall instability.

[0010] According to the first aspect, an embodiment provides a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions, the method comprising:

[0011] Combined with the analysis of geological and geophysical data in the target area, the target area is divided into stratigraphic sections;

[0012] Based on the division results of different stratigraphic sections, select the appropriate drilling structure and drilling tool combination scheme;

[0013] Drill each section in sequence. Before the current section’s borehole reaches the predetermined position, select an appropriate wall protection scheme to fix the hole wall based on the current formation conditions and construction conditions. After the current section’s borehole reaches the predetermined position, insert casing to permanently stabilize the hole wall and isolate the current section’s borehole before drilling the next section.

[0014] Furthermore, combined with the analysis of geological and geophysical data in the target area, the target area is divided into stratigraphic sections, including:

[0015] Combined with the regional geological structure map, geophysical resistivity section map and geological longitudinal section map, the target area is divided into stratigraphic sections to determine the location and length of the fault zone and its affected zone.

[0016] Furthermore, based on the division results of different stratigraphic sections, appropriate drilling structure and drilling tool combination scheme are selected, including:

[0017] According to the conditions of each formation section, choose large-diameter openings and multi-level aperture combination structures for drilling, determine the specifications of drill rods, drill bits and casings used at each level, and determine the drilling depth of each level.

[0018] Furthermore, according to the current ground conditions and construction conditions, an appropriate wall protection scheme is selected to fix the hole wall, including:

[0019] For the section with developed joints and fissures, which is a local broken section, drilling fluid is used to fix the hole and protect the wall;

[0020] For the fault-affected zone, which is a broken section with a skeleton, cement rotary jet grouting is used to fix the holes and protect the walls;

[0021] For fault zones, which are extremely broken sections, polymer gel wall protection method is used to fix the holes and protect the walls.

[0022] Furthermore, for the section with developed joints and fissures, drilling fluid is used to fix the hole and protect the wall, specifically including:

[0023] During the drilling process, the film-forming and wall-protecting properties of the drilling fluid are used to stabilize the hole wall. When suppressing the collapse of the hole and the loss of blocks, the matching components of the drilling fluid include: water, low-viscosity enhancing powder, modified asphalt, anti-collapse type drilling plugging agent, viscosity enhancer and lubricant.

[0024] Furthermore, for the fault-affected zone, cement jet grouting is used to fix the hole and protect the wall, which specifically includes:

[0025] Prepare cement slurry on site, carry the jet nozzle at the front of the drill bit and lower it into the broken section at the bottom of the hole. Inject cement slurry through the grouting high-pressure pump on site. During the injection process, adjust the jet rotation speed, cement slurry volume and pressure. At the appropriate speed and pressure, the cement slurry will penetrate into the rock mass along the pores. After the cement slurry solidifies, it can solidify the surrounding broken rocks to stabilize the hole wall.

[0026] During the process of rotary jet grouting, the drill bit is slowly pulled out toward the hole mouth while grouting. When it is pulled out to the rear of the crushing section, cement slurry is poured into the hole until the crushing section is filled. After that, displacement slurry is pressed into the hole. After the pump pressure is stabilized for a period of time, the pump is stopped and the hole is swept again after waiting for the cement to solidify, so as to stabilize the hole wall of the current section.

[0027] Furthermore, for the fault zone, a polymer gel wall protection method is used to fix the pores and protect the walls, specifically including:

[0028] Consider the influence of on-site hole depth, hole temperature and pH value on colloid performance, prepare gel formula, and determine cross-linking time, strength and retention capacity;

[0029] Calculate the amount of colloid and determine the perfusion process, which specifically includes the following steps:

[0030] ① First, calculate the volume of the open hole that needs to be cemented:

[0031]

[0032] Where: V-open hole volume of the leakage hole section, m 3 ; D-borehole diameter; L-length of the lost hole section; K-diameter expansion coefficient;

[0033] ②Configure the amount of gel according to the formula;

[0034] ③ Prepare displacement slurry, the amount used is the sum of the volumes in the drill pipe;

[0035] ④ Lower the drill pipe to the front of the crushing section, seal the orifice, pump in the prepared gel until all pumping is completed, and then pump in the displacement slurry when the gel is close to the cross-linking time, press the gel into the crushing section, and control the pump pressure during the pumping process until the pumping is completed, and stop the pump after the pump pressure stabilizes for a period of time;

[0036] ⑤ Repeat the above steps every preset length as a cycle. At the same time, during the drilling process, recharge according to the stability of the surrounding rock after gelling and the leakage situation until the fault zone is passed.

[0037] Furthermore, casing is run into the current section of the borehole to permanently stabilize the borehole wall and isolate it, including:

[0038] Before the casing is lowered, the front part of the casing carries a pipe shoe drill bit, and the casing is drilled while sweeping the hole until it reaches the predetermined position.

[0039] There will be a step gap between each level of casing. In order to prevent the casing from shaking in the hole and not affect the inclination and azimuth during drilling, the casing is fixed at the hole mouth so that each level of casing can be fixed around the center point of the borehole.

[0040] Furthermore, the method further comprises:

[0041] Before casing is lowered into each section, geophysical ultra-deep imaging equipment is used to scan the rock mass conditions in the hole and conduct geophysical in-hole tests.

[0042] According to the second aspect, an embodiment provides a complete set of hole fixing and wall protection system for ultra-deep horizontal directional holes under complex geological conditions, the system comprising:

[0043] The stratigraphic analysis module is used to divide the stratigraphic sections of the target area by combining the geological and geophysical data analysis of the target area;

[0044] The drilling plan determination module is used to select the appropriate drilling equipment combination and drilling plan based on the division results of different stratum sections;

[0045] The construction module is used to drill each section in sequence. Before the current section drilling hole reaches the predetermined position, the appropriate wall protection scheme is selected to fix the hole wall in combination with the current formation conditions and construction conditions. After the current section drilling hole reaches the predetermined position, the casing is lowered to permanently stabilize the hole wall and isolate the current section drilling hole before drilling the next section.

[0046] The present application provides a complete set of hole fixing and wall protection methods for ultra-deep horizontal directional holes under complex geological conditions. Combined with the analysis of geological and geophysical data of the target area, the target area is divided into stratigraphic sections; based on the division results of different stratigraphic sections, a suitable drilling structure and drilling tool combination scheme is selected; each section is drilled in sequence, and before the current section drilling hole reaches the predetermined position, an appropriate wall protection scheme is selected to fix the hole wall in combination with the current stratum conditions and construction conditions; after the current section drilling hole reaches the predetermined position, the casing is lowered to permanently stabilize the hole wall and isolate the current section drilling hole, and then the next section drilling is carried out. It has the following beneficial effects:

[0047] 1) The present invention provides a complete set of technical solutions for ultra-deep horizontal hole exploration under extremely complex geological conditions, and provides appropriate and targeted wall protection solutions for strata with different characteristics, which can effectively solve the problems of hole collapse, drill burial and drill jamming during the drilling process;

[0048] 2) The present invention targets extremely broken zones and adopts a solution of polymer gel pore fixation, which is rarely used in horizontal directional geological exploration holes and is a technological application innovation;

[0049] 3) The cement rotary jet grouting scheme provided by the present invention is applied for the first time to ultra-deep horizontal geological exploration holes, abandoning the previously commonly used cement slurry injection. This scheme can effectively allow the cement slurry to penetrate into the upper part of the hole wall and solidify the surrounding broken rock blocks by controlling the rotary jet flow, pressure, speed, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A flow chart of a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions provided by one embodiment of the present invention;

[0051] Figure 2 A specific implementation flow chart of a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions provided by one embodiment of the present invention;

[0052] Figure 3 A geological structure map of a tunnel area in a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions provided by one embodiment of the present invention;

[0053] Figure 4 A geophysical resistivity cross-section diagram of a tunnel entrance in a complete set of hole fixing and wall protection methods for ultra-deep horizontal directional holes under complex geological conditions provided by one embodiment of the present invention;

[0054] Figure 5 A geological longitudinal section diagram of a tunnel entrance in a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions provided by one embodiment of the present invention;

[0055] Figure 6An ultra-deep imaging result diagram of a horizontal directional hole at 390.0-398.0 m in a complete set of hole fixing and wall protection methods for ultra-deep horizontal directional holes under complex geological conditions provided by one embodiment of the present invention;

[0056] Figure 7 An ultra-deep imaging result diagram of a horizontal directional hole 517.0-526.0 m in a complete set of hole fixing and wall protection methods for ultra-deep horizontal directional holes under complex geological conditions provided by one embodiment of the present invention;

[0057] Figure 8 A schematic diagram of the logical structure of a complete set of hole fixing and wall protection system for ultra-deep horizontal directional holes under complex geological conditions is provided as an embodiment of the present invention. DETAILED DESCRIPTION

[0058] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0059] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0060] The present invention combines geological and geophysical data to determine the depth and length of the broken zone, predicts the drilling construction conditions according to the lithological characteristics and structural characteristics, and then designs the drilling structure and selects the appropriate drilling tool matching scheme; selects the corresponding wall protection method according to the formation conditions and construction conditions of the broken zone, that is, for the local broken sections with developed joints and fissures, a conventional wall protection method, that is, a drilling fluid hole-fixing and wall-blocking scheme, is adopted; for the fault-affected zone, that is, the broken sections with skeletons, a cement rotary jet grouting scheme is adopted to fix the hole and wall; for the fault zone, that is, the extremely broken section formation, a polymer gel wall protection method is used to fix the hole wall. After each corresponding broken section is penetrated, the casing of the corresponding hole grade is lowered for permanent isolation, and the hole-fixing and wall-protecting work of the whole hole is completed. The method of the present invention provides corresponding and targeted hole-fixing schemes for different formation conditions and construction conditions. Through the innovation and integration of technical applications, it effectively solves the problems of hole collapse, block drop and drill jamming in the process of ultra-deep horizontal hole exploration from shallow to deep.

[0061] The first embodiment of the present invention provides a method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions. Figure 1 and Figure 2 Provide detailed explanation.

[0062] like Figure 1 As shown, in step S100, the target area is divided into stratigraphic sections in combination with the geological and geophysical data analysis of the target area.

[0063] The above steps specifically include:

[0064] S110: Analyze the structure of the fault zone based on geological data and geophysical data, and determine the length and location of the fault zone.

[0065] The purpose of drilling in this embodiment is to find out the thickness and depth of the F1 fault at the tunnel entrance and its affected zone, and to understand the stratum lithology and hydrogeological characteristics along the tunnel. Figure 3 )、Geophysical resistivity cross section( Figure 4 )、Geological longitudinal section diagram( Figure 5 ) analysis shows that: 0.0~70.0m is the cover layer, 70.0~285.0m is the F1 fault influence zone, 285.0~545.0m is the F1 fault, 545.0~970.0m is the F1 fault influence zone, and 970.0~1250.0m is the complete bedrock.

[0066] S120: Predict construction hazards that may occur during drilling based on the lithology characteristics and geological structure of the strata.

[0067] Based on the division of stratigraphic sections by S110, combined with the results of regional geological survey and mapping, regional lithological characteristics, and structural characteristics, it can be determined that:

[0068] The lithology of the overburden layer (0.0-70.0m) is mainly erosion angular gravel and gravel soil. The main characteristics of this section are looseness, poor cementation, and large voids. It is very easy to collapse the hole, get the drill stuck, and leak slurry during drilling;

[0069] The fault-affected zone (70.0-285.0 m) on the right side of the F1 fault is composed of fully weathered to strongly weathered quartz schist of the Silurian system. The rock is relatively soft, with developed joints and fissures and structural planes. In addition, due to the influence of the fault, the rock mass is broken into brecciated, blocky, and medium-thin layers. This section is prone to collapse and block shedding at the top of the borehole during drilling.

[0070] F1 fault (285.0-545.0m), the lithology of this section is mainly Silurian strongly weathered to moderately weathered quartz schist. Affected by tectonic activities, the strata in this section are extremely broken and may have been crushed into breccia and fragments. The cementation is very poor, and it is very easy to collapse and gush water during drilling. The top of the borehole will continue to collapse, and the drilling trajectory is also very easy to deviate;

[0071] The fault-affected zone on the left side of F1 fault (545.0-970.0m) is composed of medium-weathered quartz schist of Silurian system. The rock is relatively soft, with well-developed joints and structural planes. The rock mass is mainly in medium-thick blocky form. Affected by the fault, the rock mass is partially broken. Blocks are easily lost in the broken rock mass section during drilling. Due to the soft rock mass, there is a lot of rock powder during drilling. In addition, the hole is deep, so it is difficult to discharge slag and the inner pipe is easily blocked.

[0072] 970.0~1250.0m is Silurian marble, the rock mass is relatively complete and it is a relatively hard rock, so the drilling process is relatively easy. However, marble is easily dissolved, so leakage must be prevented during the drilling process.

[0073] like Figure 1 As shown, in step S200, based on the division results of different stratum sections, a suitable drilling structure and drilling tool combination scheme is selected.

[0074] The above steps specifically include: selecting large-diameter openings and multi-level aperture combination structures for drilling in accordance with the conditions of each formation section, determining the specifications of the drill rods, drill bits and casings used at each level, and determining the drilling depth of each level.

[0075] According to S110 and S120, it can be concluded that the geological conditions of the hole are extremely complex, the fault zone and its influence zone are extremely thick and deep, and the drilling difficulty is unprecedented. Combined with the formation conditions, a large-diameter hole and a multi-level aperture combination structure are selected for drilling.

[0076] The drilling structure adopts 6-level drilling and 5-level casing isolation and wall protection. The first level uses JS114 drill rod + Φ200 drill bit combination to open the hole, penetrate the loose covering layer to 12m, and install Φ194 casing as the hole protection pipe; the second level uses JS114 drill rod + Φ172 to penetrate the covering layer, drill to 73m, and install Φ168 casing for isolation; the third level uses JS114 drill rod + Φ150 drill bit combination to drill to 29 according to the situation in the hole and the power of the drilling rig. 0m, Φ146 casing with a pipe shoe drill bit was installed; the fourth level used JS114 drill pipe + Φ122 drill bit combination for drilling, penetrated the F1 fault and drilled to 550m, and Φ114 casing with a pipe shoe drill bit was installed; the fifth level used JS91B drill pipe + Φ98 drill bit combination for drilling, passed through the F2 fault zone and drilled to 976m, and Φ95 casing was installed according to the situation in the hole; the sixth level used JS75B drill pipe + Φ78 drill bit combination for drilling, and drilled to 1250m.

[0077] like Figure 1 As shown, in step S300, each section is drilled in sequence. Before the current section drilling hole reaches the predetermined position, an appropriate wall protection scheme is selected to fix the hole wall in combination with the current formation conditions and construction conditions. After the current section drilling hole reaches the predetermined position, casing is lowered to permanently stabilize the hole wall and isolate the current section drilling hole before drilling the next section.

[0078] The above steps specifically include:

[0079] S310. Select the wall protection method for each section according to the drilling conditions in the hole

[0080] When drilling at each level before reaching the corresponding position, the block falling, pipe sticking and leakage that occur during the drilling process can only be stabilized by applying mud method. After penetrating the section to reach the predetermined position, the hole wall can be permanently stabilized by casing isolation.

[0081] During the drilling process, it is necessary to determine which wall protection method to use based on the drilling conditions in the hole, the conditions of the core taken out, and the operating status of the drilling rig. On the one hand, it must be able to adapt to the section of the formation, and on the other hand, it must match the current drilling efficiency.

[0082] Based on this, the hole conditions are divided into three categories:

[0083] (1) In the section with developed joints and fissures, the rock mass is relatively broken, and small-scale block falling and slurry leakage may occur in this section. For this section, the drilling fluid wall protection method is adopted.

[0084] (2) For the fault-affected zone (section with skeleton fragmentation), the strata in this section are affected by the fault, the rock mass is fragmented and in block and short columnar shape, with weak cementation. It is easy to fall off and collapse after being disturbed by drilling. For this section, the method of rotary grouting in cement holes is adopted to connect the rock blocks with cement to make them a whole.

[0085] (3) In the fault zone, the rock mass has been crushed into angular and sandy forms due to tectonic activity. The hole will continue to collapse during the drilling process, making it impossible to drill further. For this section, gel pre-injection is used to cement it into a whole, thereby achieving the effect of stabilizing the hole wall.

[0086] S311: For sections with developed joints and fissures (partially more broken sections), drilling fluid is used to fix the holes and protect the walls.

[0087] In the section with developed joints and fissures, the rock mass is relatively broken, and small-scale block falling and slurry leakage may occur in this section. For this section, the drilling fluid wall protection method is adopted.

[0088] There are many ways to protect the wall with drilling fluid. According to different chemical materials, formation lithology, and drilling conditions in the hole, the blending formulas are also varied, but the overall policy and principle are basically the same, that is, to use the film-forming and wall-protecting properties of the drilling fluid to stabilize the hole wall during the drilling process, such as: water + 4.0% low-viscosity enhancement powder + 2.0% modified asphalt + 3.0% anti-collapse type drilling plugging agent + 0.1% high-viscosity cellulose + 0.5% lubricant.

[0089] S312: For fault-affected zones (sections with broken skeletons), cement jet grouting is used to fix holes and protect walls.

[0090] For the fault-affected zone, that is, the broken section with a skeleton, this section of the stratum is affected by the fault, the rock mass is broken, and is in block and short columnar shape with weak cementation. It is easy to fall off and collapse after being disturbed by drilling. For this section, the method of rotary grouting in cement holes is adopted.

[0091] Cement slurry is prepared on site, and the front part of the drill tool carries the rotary jet head and is lowered into the broken section at the bottom of the hole. Cement slurry is injected on site through a grouting high-pressure pump. During the injection process, the rotary jet rotation speed, cement slurry volume and pressure are adjusted. Under appropriate speed and pressure, the cement slurry will penetrate into the rock mass along the pores for several to tens of centimeters. After the cement slurry solidifies, it can solidify the surrounding broken rock blocks to stabilize the hole wall. During the rotary jet grouting process, the drill tool needs to be slowly pulled out toward the hole mouth while grouting. When it is pulled out to the rear of the broken section, cement slurry is poured into the hole until the broken section is filled. After that, displacement slurry is pressed into the hole. After the pump pressure is stabilized for a period of time, the pump is stopped. Wait for the cement to solidify and then the hole is swept to stabilize the hole wall.

[0092] S313: For fault zones (extremely broken sections), gel pore-fixing wall protection is used

[0093] In the fault zone, the rock mass has been crushed into angular and sandy states by tectonic activities, and hole collapse will continue to occur during the drilling process. Continuous hole sweeping and punching will only intensify the large-scale falling of the upper part of the hole wall, and even form a big belly, making it impossible to drill at all.

[0094] In view of this extremely complex situation, it is necessary to use polymer gel to fix the pores. Polymer gel is a viscoelastic substance formed by the mutual reaction of multiple polymers. Before forming a colloid, it has good fluidity. After reaching the gel time, it quickly forms a three-dimensional network structure. The polymer gel loses its fluidity and has a good retention effect. It has both outstanding free cross-linking ability and the ability to freely deform and squeeze into the cracks of the broken zone. In addition, polymer gel also has the characteristics of controllable gelation time, wide temperature adaptability, and high plugging strength.

[0095] (1) Adjust the gel formula according to the pore depth, temperature, pH, etc., and determine the cross-linking time, strength, and retention capacity

[0096] The key technical indicators in the gelling process are gelling time and gelling strength. If the gelling time is too long, the wall protection process will take a lot of time, the gelling strength will also decrease over time, and the success rate of gelling is low. If the gelling time is too short, it is easy to gel in the drill pipe. There are many kinds of synthetic materials for gelling. The ratio of polymer and cross-linking agent determines the gelling viscosity and gelling time. At this time, it is necessary to determine the gelling time according to the hole depth and injection time on site to ensure that the gel can be injected into the broken section at the bottom of the hole when it is in a fluid state. In the process of mixing, the temperature in the hole and the pH value of water on the performance of the colloid should also be considered. Some additives can also be added to the colloid to improve the performance of the colloid, delay or speed up the reaction time, increase or decrease the viscosity of the colloid, and increase the pressure bearing capacity of the colloid, so as to achieve the target requirements.

[0097] For example, if 3% polyacrylamide (PVA) + 2% borax is used for cross-linking, and then 0.3% carboxymethyl cellulose (CMC), 0.6% retarder (GH-8), and 3% sawdust are added thereto, the cross-linking temperature is 30-45°C, the gelling time is 74-91min, the gelling viscosity is 247400-254400mPa·s, and the pressure bearing capacity is 5.8MPa.

[0098] (2) Calculate dosage and determine the injection process

[0099] ① First, calculate the volume of the open hole that needs to be cemented:

[0100]

[0101] Where: V-open hole volume of the lost hole section, m3; D-drilling diameter; L-length of the lost hole section; K-diameter expansion coefficient, generally 1.1;

[0102] ②Configure the amount of gel according to the formula;

[0103] ③ The amount of displacement slurry (such as clean water + 3% vegetable glue) used is the sum of the volumes in the drill pipe;

[0104] ④ Lower the drill pipe to the front of the crushing section, seal the orifice, pump in the prepared gel until all pumping is completed, and then pump in the displacement slurry when the gel is close to the cross-linking time, press the gel into the crushing zone, control the pump pressure during the pumping process until the pumping is completed, and stop the pump after stabilizing the pump pressure for a period of time.

[0105] ⑤ Repeat the above steps every certain distance (such as 7 to 10 meters) as a cycle. At the same time, during the drilling process, recharge according to the stability of the surrounding rock after gelling and the leakage situation until the fault zone is passed.

[0106] S320. Ultrasonic imaging inspection and comprehensive testing in geophysical exploration boreholes

[0107] Before casing is lowered into each section, the rock mass condition in the hole is scanned using geophysical ultra-deep imaging equipment, such as Figure 6 and Figure 7 As shown, geophysical in-hole tests are carried out to provide geologists with more detailed and abundant drilling data. Through these two methods, geologists can more clearly judge the basic conditions of the tunnel surrounding rock.

[0108] S330. Pipe shoe drilling and casing isolation

[0109] S331: Use the combination of pipe shoe drill bit + casing to drill to the predetermined position

[0110] According to the drilling structure design, after penetrating the corresponding section under the action of the wall protection scheme, it is necessary to lower the drilling tool or casing of the corresponding aperture to permanently stabilize the hole wall, laying the foundation for the smooth implementation of the next section. Due to the extremely broken strata, coupled with the disturbance and pumping during the drilling process, the stability of the rock mass will become worse and worse. Therefore, before the casing is lowered, the front part of the casing carries a pipe shoe drill bit, and the drilling is carried out while sweeping the hole during the lowering process until it reaches the predetermined position.

[0111] S332: Orifice fixed casing

[0112] There will be a step gap between each level of casing. In order to prevent the casing from shaking in the hole and affecting the inclination and azimuth during drilling, it is necessary to fix the casing at the hole mouth so that each level of casing can be fixed around the center point of the borehole.

[0113] S333: Start the next stage of drilling process

[0114] When each stage of casing is lowered, the unstable hole wall of the previous section will be effectively isolated, and drilling of the next section can begin.

[0115] The embodiment of the present invention provides a complete set of hole fixing and wall protection method for ultra-deep horizontal directional holes under complex geological conditions, which has the following advantages:

[0116] 1) The invention has strong versatility. It is applicable to the fixing and wall protection of all horizontal directional geological exploration holes, and is also applicable to vertical geological exploration holes.

[0117] 2) The invention is highly operable and practical. All the solutions provided by the invention can be realized on site through simple operations.

[0118] 3) Highly targeted: the present invention proposes appropriate and targeted solutions for different stratum conditions, thus avoiding blind operations.

[0119] 4) The applicability and flexibility are stronger. The hole fixing and wall protection schemes of the present invention can be selected according to the situation in the hole, can be combined in pairs, or can be combined arbitrarily.

[0120] 5) Safety is significantly improved. The present invention reasonably sets the aperture structure casing grading, timely isolates the unstable section of the previous section, lays the foundation for the smooth implementation of the next section, and significantly improves the safety and stability of the borehole.

[0121] 6) The systematic and simplified technology system of hole-fixing and wall-protecting process established by the present invention has broad prospects for the application of horizontal directional holes, and can also promote the new technology of horizontal directional geological exploration holes to go further and be more widely used.

[0122] Corresponding to the above-disclosed method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions, the embodiment of the present invention further discloses a system for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions, such as Figure 8 As shown, it specifically includes:

[0123] The stratigraphic analysis module is used to analyze the geological and geophysical data of the target area and divide the stratigraphic sections of the target area;

[0124] The drilling plan determination module is used to select the appropriate drilling structure and drilling tool combination plan based on the division results of different stratum sections;

[0125] The construction module is used to drill each section in sequence. Before the current section drilling hole reaches the predetermined position, the appropriate wall protection scheme is selected to fix the hole wall in combination with the current formation conditions and construction conditions. After the current section drilling hole reaches the predetermined position, the casing is lowered to permanently stabilize the hole wall and isolate the current section drilling hole before drilling the next section.

[0126] It should be noted that for the detailed description of a complete set of hole fixing and wall protection system for ultra-deep horizontal directional holes under complex geological conditions provided in an embodiment of the present invention, reference can be made to the relevant description of a complete set of hole fixing and wall protection method for ultra-deep horizontal directional holes under complex geological conditions provided in an embodiment of the present application, and no further details will be given here.

[0127] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A complete set of hole fixing and wall protection method for ultra-deep horizontal directional holes under complex geological conditions, characterized in that: The method comprises: Combined with the analysis of geological and geophysical data in the target area, the target area is divided into stratigraphic sections; Based on the division results of different stratigraphic sections, select the appropriate drilling structure and drilling tool combination scheme; Drill each section in sequence. Before the current section’s borehole reaches the predetermined position, select an appropriate wall protection scheme to fix the hole wall based on the current formation conditions and construction conditions. After the current section’s borehole reaches the predetermined position, insert casing to permanently stabilize the hole wall and isolate the current section’s borehole before drilling the next section.

2. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 1, characterized in that: Combined with the analysis of geological and geophysical data in the target area, the target area is divided into stratigraphic sections, including: Combined with the regional geological structure map, geophysical resistivity section map and geological longitudinal section map, the target area is divided into stratigraphic sections to determine the location and length of the fault zone and its affected zone.

3. The method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 1, characterized in that: Based on the division results of different stratigraphic sections, select the appropriate drilling structure and drilling tool combination scheme, including: According to the conditions of each formation section, choose large-diameter openings and multi-level aperture combination structures for drilling, determine the specifications of drill rods, drill bits and casings used at each level, and determine the drilling depth of each level.

4. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 1, characterized in that: According to the current ground conditions and construction conditions, select appropriate wall protection scheme to fix the hole wall, including: For the section with developed joints and fissures, which is a local broken section, drilling fluid is used to fix the hole and protect the wall; For the fault-affected zone, which is a broken section with a skeleton, cement rotary jet grouting is used to fix the holes and protect the walls; For fault zones, which are extremely broken sections, polymer gel wall protection method is used to fix the holes and protect the walls.

5. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 4, characterized in that: For the section with developed joints and fissures, drilling fluid is used to fix the hole and protect the wall, including: During the drilling process, the film-forming and wall-protecting properties of the drilling fluid are used to stabilize the hole wall. When suppressing the collapse of the hole and the loss of blocks, the matching components of the drilling fluid include: water, low-viscosity enhancing powder, modified asphalt, anti-collapse type drilling plugging agent, viscosity enhancer and lubricant.

6. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 4, characterized in that: For the fault-affected zone, cement jet grouting is used to fix the hole and protect the wall, including: Prepare cement slurry on site, carry the jet nozzle at the front of the drill bit and lower it into the broken section at the bottom of the hole. Inject cement slurry through the grouting high-pressure pump on site. During the injection process, adjust the jet rotation speed, cement slurry volume and pressure. At the appropriate speed and pressure, the cement slurry will penetrate into the rock mass along the pores. After the cement slurry solidifies, it can solidify the surrounding broken rocks to stabilize the hole wall. During the process of rotary jet grouting, the drill bit is slowly pulled out toward the hole mouth while grouting. When it is pulled out to the rear of the crushing section, cement slurry is poured into the hole until the crushing section is filled. After that, displacement slurry is pressed into the hole. After the pump pressure is stabilized for a period of time, the pump is stopped and the hole is swept again after waiting for the cement to solidify, so as to stabilize the hole wall of the current section.

7. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 4, characterized in that: For fault zones, the polymer gel wall protection method is used to fix the pores and protect the walls, including: Consider the influence of on-site hole depth, hole temperature and pH value on colloid performance, prepare gel formula, and determine cross-linking time, strength and retention capacity; Calculate the amount of colloid and determine the perfusion process, which includes the following steps: ① First, calculate the volume of the open hole that needs to be cemented: Where: V-open hole volume of the leakage hole section, m 3 ; D-borehole diameter; L-length of the lost hole section; K-diameter expansion coefficient; ②Configure the amount of gel according to the formula; ③ Prepare displacement slurry, the amount used is the sum of the volumes in the drill pipe; ④ Lower the drill pipe to the front of the crushing section, seal the orifice, pump in the prepared gel until all pumping is completed, and then pump in the displacement slurry when the gel is close to the cross-linking time, press the gel into the crushing section, and control the pump pressure during the pumping process until the pumping is completed, and stop the pump after the pump pressure stabilizes for a period of time; ⑤ Repeat the above steps every preset length as a cycle. At the same time, during the drilling process, recharge according to the stability of the surrounding rock after gelling and the leakage situation until the fault zone is passed.

8. The method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 1, characterized in that: Casing is run into the current section of the borehole to permanently stabilize the borehole wall and isolate it, including: Before the casing is lowered, the front part of the casing carries a pipe shoe drill bit, and the casing is drilled while sweeping the hole until it reaches the predetermined position. There will be a step gap between each level of casing. In order to prevent the casing from shaking in the hole and not affect the inclination and azimuth during drilling, the casing is fixed at the hole mouth so that each level of casing can be fixed around the center point of the borehole.

9. A method for fixing and protecting the wall of an ultra-deep horizontal directional hole under complex geological conditions as claimed in claim 1, characterized in that: The method further comprises: Before casing is lowered into each section, geophysical ultra-deep imaging equipment is used to scan the rock mass conditions in the hole and conduct geophysical in-hole tests.

10. A complete set of hole fixing and wall protection system for ultra-deep horizontal directional holes under complex geological conditions, characterized in that: The system comprises: The stratigraphic analysis module is used to analyze the geological and geophysical data of the target area and divide the stratigraphic sections of the target area; The drilling plan determination module is used to select the appropriate drilling equipment combination and drilling plan based on the division results of different stratum sections; The construction module is used to drill each section in sequence. Before the current section drilling hole reaches the predetermined position, the appropriate wall protection scheme is selected to fix the hole wall in combination with the current formation conditions and construction conditions. After the current section drilling hole reaches the predetermined position, the casing is lowered to permanently stabilize the hole wall and isolate the current section drilling hole before drilling the next section.

Images