Drilling drilling technology.
The concept of drilling for heart
Drilling drilling refers to the purpose of mastering the underground geology. Directly obtain the real and reliable underground rock layer, and use the drilling tool to remove large rock samples (cores) from the ground during the drilling process.
Conventional heart
Heart without any special requirements for the core is called conventional centering. Conventional centering is the largest and most common in core taking operations. No matter what reservoir, a large number of conventional centering should be carried out in the exploration or development stage.
1. Main purpose
① Discover the oil and gas layer, understand the oil and gas content and storage characteristics, and determine the lithology, physical properties, thickness, area and other basic data of the oil and gas layer.
② Establish the stratigraphic profile, study the rock phase and growth and storage characteristics,
③ Understand the relationship between lithology and electrical properties.
2. Conventional centering method
① General short tube heart, refers to the heart drilling midway is not a single root of the conventional core. Its tools can only contain a section of the core tube, and the structure is simple. It occupies the largest proportion of the whole cooperation and can be carried out under any formation conditions.
② Medium, long tube for the heart, refers to the drilling midway to take a single root of the core. Its tools must contain multiple section core cylinder, usually only when the formation rock cement and drilling ability is good, the medium and long cylinder core. The purpose of medium and long barrel is to improve the single barrel footage of core as far as possible on the premise of ensuring the high harvest rate of core, so as to greatly improve the harvest rate and reduce the cost of core.
Special heart
Drilling core with certain special requirements for rock core is called special core core. It is mostly used in the oilfield development stage, usually has the following parties
1) The ing of oil-based drilling fluid refers to the core of oil-based drilling fluid. For sandstone and clay reservoirs with large reserves, this diversion is generally carried out before development, and the purpose of this is to obtain the core that is not free of water pollution by drilling and liquid, in order to obtain a more accurate original oil saturation data of the reservoir and provide a basis for the reasonable formulation of oilfield development plan. Because the oil base drill and liquid does not lose water, stable performance, fluidity and lubricity are very good, so the core has no problem of water absorption expansion or peeling, is not easy to break or wear, the core rules, integrity, good column, high harvest rate.
2) airtight core, refers to the sandstone oilfield, in the process of development, to check the oilfield water injection development effect, understand the underground layer washing and oil and water dynamic, to develop reasonable development adjustment scheme, the airtight heart tool and airtight liquid, under the condition of water-based drilling fluid almost free water pollution of drilling fluid core. Due to the high cost of oil based drilling fluid, closed drilling fluid can replace oil based drilling fluid under the premise that the quality index of closed core is guaranteed.
3) Sponge centering refers to the core of the inner core tube equipped with a special sponge lining tube. Using pre-saturated sponge lining pipe, we can achieve quite accurate oil saturation core under water-based drilling fluid conditions. This is a kind of foreign countries developed in recent years, the process structure is not too complex, but the cost is high, suitable for medium hard ~ hard formation.
4) Pressure sealing and sealing refers to the fluid saturation of the reservoir under the condition of the well bottom in the late development of the sandstone oilfield. In the data of reservoir pressure, relative humidity and reservoir conditions, in order to develop a reasonable development and adjustment scheme and improve the final recovery of the oil field, the pressure sealing core tool and sealing fluid are used to maintain the fluid integrity of the reservoir core under the condition of water-based drilling fluid. That is to drill the core that is not freely contaminated by drilling fluid and maintains the reservoir pressure under the bottom conditions. This kind of centering equipment and process is relatively complex and high cost, suitable for soft, medium hard and hard strata with lithology.
5) Loose sandstone conformal core, refers to the core that maintains the original (before simplified) shape of the core in the loose sandstone formation. Because in the loose sandstone stratum, because of the low core strength, the column is not available, the core will often become a pile of loose sand after the core goes out of the cylinder, and the core material data can not be obtained. Therefore, maintaining the original shape of the core and avoiding man-made damage have become the key to conformal core technology. At present, multi-stage double-composite core cylinder, rubber cylinder, fiberglass inner cylinder and composite material liner can meet the requirements of retaining shape and center, but only multi-stage double-valve composite core cylinder has low cost and easy to use.
6) Directional centering refers to the economical and reasonable exploration and development plan in the process of oil and development in order to intuitively understand the structural parameters of the reservoir, comprehensively grasp the complexity and changes of the geological structure, and adopt the directional core technology to take out the core that can reflect the structural parameters such as stratum inclination, tendency and direction. Oriented centering is only suitable for strata with good core formation.
coring tool
Composition of the centering tool
The centering tool is composed of upper stabilizer, water tap, plugging steel ball, outer return nozzle, suspension assembly, inner core group, outer core stabilizer, combined inner shoe, core claw, and centering drill bit.
The main function of the core drilling bit is to form the core, while the main function of the centering tool is to protect the core and remove the core. Obviously, it is impossible to take the core with high quality without a suitable centering tool. According to the heart cutting method, the current domestic and foreign centering tools can be divided into three types: pressure, self-locking and sand card
When cutting the core, lower the drilling tool, the core of the core claw by the drilling pressure and the sliding force of the inner cylinder, wrap, break or twist the core is called the pressurized core tool. When cutting the core, the drilling tool with the core grasping by its own elastic force or the friction force between it and the core is called the self-locking core tool.
Take the heart tool to choose
1. Selection of core tools under different well depth conditions Select short cylinder in shallow well and medium long cylinder in deep well.
2. Select the centering tools according to the formation lithology
Prespression centering tool should be used in loose and soft strata, while self-locking centering tool should be used in soft strata with medium ~ hard strata and soft strata with good core formation.
At present, diamond drilling bit is widely used for drilling at home and abroad.1) Diamond drill has good effect, especially the tire type diamond drill, which can ensure the uniform blade of the drill. Diamond wear resistance, tire body corrosion resistance, so smooth drilling, fast speed, high harvest rate, long service life, good comprehensive economic benefits 2) diamond core drilling bit wide application range. From the extremely soft to the extremely hard formation, there are various series of diamond core drills for choice, which can fully meet the needs of the heart under various conditions.
3, the tire body diamond core drill bit is easy to form, easy processing, high yield,
Prepare before taking your heart
Well eye preparation
1) At the beginning of drilling, we should maintain a good quality of the well, to prevent the shaft inclined, dog leg, key groove, shoulder, diameter, etc. 2) Before the center of a drill should take a salvage cup, to repair the bottom of the flat well. Large displacement cycle removes the sand at the bottom of the well, and carries out short drilling when necessary to ensure that the well bottom is clean, smooth and smooth.
3) Continuous heart, every 20 meters to drill once.
Preparation of equipment, instruments and drilling tools
1) Before centering, the equipment and instrument should be checked and maintained to ensure continuous drilling during the centering.
2) Conduct a comprehensive inspection of the drilling tools to ensure that no puncture, leakage or buckle during the coperiod.
3) The centering tools, accessories, auxiliary tools and drills should be further checked to avoid shutdown due to tools and accessories.
Take the heart operation procedure
1, centering tool assembly
1) Put the centering tool flat on the ground, and the connecting thread of each section should be tightened with chain pliers, and both ends should be equipped with protective wire.
2) Check whether the outer diameter of the stabilizer is consistent with the drill bit, and measure the length of the heart tube.
3) After lifting on the drilling rig, use the card to go into the well, use the card under the upper stabilizer, and use the safety card to remove
4) Remove the safety joint, put forward the inner cylinder, connect the inner shoe equipped with the core claw to the inner cylinder, and tighten it with the chain clamp
5) Lower into the inner cylinder,. Check whether the safety joint and bearing are flexible, coated with wire buckle oil (not too much), tighten the chain pliers after the buckle, and finally fasten the buckle with large pliers.
6) Put the core cylinder forward to the well head, remove the lower guard wire, and check the longitudinal clearance with a special ruler, generally 8~13 mm. If it is not appropriate, adjust by adding or subtracting gaskets, and then connect the checked centering drill bit, and the connecting thread of each section should be tightened with large pliers
2. Drill
The well section with reduced diameter should be slowly entered, if blocked, the pump cycle should be opened first, and the short well section with low drilling pressure, low speed, large displacement, drilling requires stable operation, no fierce release, fierce stop, fierce brake, fierce turn, to prevent the drilling tool from swinging violently. In the well, oblique larger, short time delimit eye. It is forbidden to drill large drilling (more than 10 meters) or force drilling.
3. recurrence
When the drilling is 0.5~1 meter from the bottom of the well, cycle the drilling fluid and move smoothly and rotate the drilling tool appropriately. Correct the weight gauge, remove the drill tool, and put the steel ball. After the pump pressure rises, do the drill bit pressure drop test
4. Make heart
Start the rotary table first, and apply the drilling pressure slowly, and test it with low speed and light drilling pressure. After smooth operation and drilling of 0.3~0.5 meters, gradually adjust to the normal centering drilling parameters.
5. Get into
(1) Drilling pressure
The drilling pressure during centering drilling shall be determined according to the hardness and drilling ability of rock, drill type and structure and strength of drilling tools. The drilling pressure must be greater than the compressive strength of the formation, otherwise, there is no footage. If the drilling pressure is too small, the teeth of the drill eat less into the formation, although there are footage, the drilling speed is slow, the drill wear is also fast: the greater the drilling pressure, the deeper the drill eats into the formation: the higher the drilling speed
At present, the cutting effect of the diamond drill mainly determines the stable contact degree between the dry diamond and the drilling formation, the same speed, the increase of the drilling pressure, observe the change of the drilling speed is no longer increased or increases quite slowly, or the torque increases greatly, then the drilling pressure at this time is the optimal drilling pressure. If a satisfactory drilling rate has been achieved, the drilling pressure should be kept constant and delivered uniform
2) RPM
Theoretically speaking, under a certain limit, if the depth of the drill bit into the formation remains unchanged, the speed is increased, the drilling speed will be increased, and the time of the core into the barrel will be shortened, which is conducive to improving the harvest rate of the core. However, the higher speed will swing the drill bit to increase the transverse force and the centrifugal force of the drill column, which is bad for protecting the core and the drill bit. In fact, the drill bit working at the bottom of the well is also affected by many other factors. Therefore, in order to protect the core, a low speed should be used to reduce the centrifugal force
(3) displacement of the core cylinder
The size of the displacement is properly selected on the premise of cleaning the well bottom and cooling the drill bit. The discharge is too large, and the drilling fluid from the drill hole is of a large impact force. Although it is not directly impacted on the whole core, it is also a destructive force to the core root for the soft formation or not hard enough formation. To protect the core, the displacement should be smaller.
6. Receive a single root
In the process of centering the medium and long tube, the single root operation should be carried out. The method of connecting the single root of the self-locking centering tool is to stop drilling, stop the pump, and then lift the drilling tool until the core is cut. If lift pull to a certain value and the core also cut constantly, can keep under the pull open pump cycle, until the core cut, after the core cut, keep drilling rotation, smooth ground 2~3 meters and then slowly down to 0.3 meters from the bottom, observation refers to the change of the weight table, confirm no core in the bottom, can be single root. After receiving a single root, enter the drilling tool and apply the drilling pressure core claw which is 50% larger than the core drilling pressure. After the lifting tool recovers the original suspension weight, the drilling is carried out according to the method of starting the heart.
7. Cut the heart
(1) Heart cutting under normal conditions
The position of the core can be determined according to the length of the inner core in the medium hard or hard formation with good rock homogeneity and column formation. When the core is taken in the strata with uneven rocks and complex changes, try to choose the position of the inner core in the relatively hard strata, and do not force more footage. After cutting the core, pick up the drilling tools at different heights, and slowly lower the drilling tools in different directions to explore the center. If there are more residual parts at the bottom of the well, in order to get all the accurate data, "set".
(2) Heart cutting under abnormal conditions
In the centering drilling, if the drill mud package, the drill circulation channel is blocked, and the abnormal core grinding "," core jamming "," core "blocking", "and" heartburn " cannot be excluded, the heart must be cut immediately.
8. Drill
The drilling operation should be smooth, to light lift, light release, slow unloading, to prevent the drilling tool from swinging violently, prohibit the rotary table unloading.
9. Rock core out of the tube
No matter in the drilling platform or in the site, attention should be strictly paid attention to the simple sequence of the core to prevent core dislocation. The operation method is to first remove the safety joint, put forward the inner cylinder, rinse clean, unload the inner shoe 2~3 buckle, pull the inner cylinder to the place where the driller is easy to see, plug the inner cylinder with a rope, remove the inner shoe, install the core pliers, and then the driller operation, one up and down, release the core,
If it is aluminum alloy and glass fiber reinforced plastic tube center, remove the safety joint, above 0.2 meters, with dial stuck inner cylinder, and sit on the outer cylinder, with chain clamp open safety joint, lift the cylinder and core lift drilling platform, flat on the site, water rinse clean, according to the geological requirements, with chainsaw section cut, and the core cap seal, with a good card.