In order to meet the requirements of drilling process technical measures and drilling construction quality, the solid control system during complex drilling construction operations was optimized. Solve the problems of drilling solid control system, high quality drilling fluid solid control system, improve the performance of solid control equipment, reduce the solid phase content in drilling fluid, improve the quality of cementing construction, and ensure that drilling construction meets the design quality standards.
Solid control system
Solid control system in complex drilling operations
For oil drilling operations, straight wells are the simplest drilling construction task. The directional and horizontal wells are difficult to drill and belong to complex drilling operations. For horizontal well drilling operations, vertical well sections, inclined well sections, stable inclined well sections, and horizontal well sections need to be drilled. Each well section needs to be matched to form a reasonable borehole trajectory and achieve the quality of horizontal well drilling construction. .
The solid control system for drilling construction is to meet the technical requirements for solid control of drilling fluids. Through solid control equipment, the solid phase content in drilling fluids can be reasonably controlled, and the purification of drilling fluids can be strengthened so that its performance can meet the technical requirements of complex drilling constructions. Reduce the cost of drilling construction as much as possible, improve the quality of oil drilling construction, and meet the needs of oil and gas field exploration and development.
The solid control system in the oil drilling process mainly realizes the control and separation of the solid phase and the liquid phase of the drilling fluid, and recycles the drilling fluid, which also belongs to the mud purification system. The solid control system is composed of several modular combined tanks to avoid the occurrence of sediment at the bottom of the mud tank . A mixing device is designed on the mud tank . Each tank of the entire circulation system is independent and connected to each other to form Certain technological processes meet the requirements of mud purification and meet the technical requirements of petroleum drilling construction.
Multiple purification equipment is designed in the system, and the supporting equipment includes vibrating screen, agitator and desilter, etc. to reduce the discharge of waste cement slurry, avoid environmental pollution accidents, improve the safety and environmental protection of oil drilling construction, and achieve need.
Analysis of complex drilling procedures
The screw propeller is a major component of the drilling fluid centrifuge. Its structure, materials and parameters are directly related to the separation effect, production capacity and service life of the drilling fluid centrifuge . As long as the function of the spiral is to push sediment, its requirements are different in the settlement area and the drying area. The solid particles in the suspension in the sedimentation zone gradually form a sedimentation zone toward the drum wall. The spiral should be conducive to moving the sedimentation without violently stirring up the sedimentation, causing the separated sedimentation and liquid phase to mix. In the drying zone, the spiral should not only continue to move the sediment, but also create favorable conditions for sediment and water separation.
The screw propeller is generally composed of a screw blade, an inner cylinder and a feeding chamber.
Spiral blades are components that directly contact the sediment to transport it. The common forms are:
A: Connected to the whole spiral blade, commonly used and easy to manufacture
B: Continuous ribbon-shaped spiral blades. The blades have poor rigidity and are not used much. They are mainly used for sedimentation and separation.
C: disconnected spiral blade
D: spiral blade with additional blades
Spiral is divided into single-headed and double-headed. Because double-headed spirals are easy to process and balance, they are mostly double-headed spirals.
There are two types of spiral blades. One is that the spiral blades are perpendicular to the drum busbar. This is convenient for welding and calibration. It is often used in design. One is that the blade is perpendicular to the axis of rotation.
Because the blade of the propeller directly contacts the sediment, the blade has high requirements on the material, and the blade needs to have high abrasion resistance. Generally, the surface of the blade is surfacing or spray-welded with cemented carbide, which is difficult to process. At present, a new process for manufacturing wear-resistant blades has appeared, which is characterized in that the wear-resistant sheet is fixed to the tile-shaped workpiece by brazing, welding or bonding, and then the two assembly is welded to the spiral blade, so that The centrifuge maintains a high production capacity.
"Green drilling" refers to drilling that focuses on pollution prevention, minimizes consumption of raw materials and energy, reduces production costs, and reduces and prevents damage to the ecological environment during the drilling process.
In order to carry the broken cuttings of the bottom drill bit to the surface in time to continue drilling, and at the same time to cool the drill bit to protect the well wall and prevent drilling accidents such as well collapse, the rotary drilling rig is equipped with a circulation system. The circulation system includes drilling pumps, ground manifolds, mud tanks, mud purification equipment, etc. Among them, ground manifolds include high-pressure manifolds, risers, and water hoses, and mud purification equipment includes drilling fluid shakers , sand removers, desilter, Centrifuge, etc.
The drilling pump sucks the mud from the mud tank, and the mud pressurized by the drilling pump passes through the high-pressure manifold, riser, and water hose, enters the faucet, goes down to the bottom of the well through the hollow drilling tool, and is ejected from the water hole of the drill bit. Through the circular space between the wellbore and the drilling tool, rock debris is carried back to the ground, and the mud returned from the bottom of the well is passed through various levels of mud purification equipment to remove the solid content and then reused.
Drilling engineering is a field operation project in oil and gas exploration and development activities. The "waste slurry, waste water, waste oil" and the debris such as rock cuttings and production garbage during the drilling production process inevitably cause pollution and damage to the surrounding environment. Especially in sensitive ecologically fragile areas, the damage will be severe and difficult to repair once it occurs. Therefore, vigorously promoting clean production and actively realizing sustainable development "establish green awareness of environmental protection, control pollution from the source, and achieve green environmental protection of oil and gas exploration and development, has become the incumbent responsibility and obligation of today's oil and gas exploration and development enterprises.
Four-level solid control equipment drilling fluid circulation system can strengthen the solid phase control of drilling fluid; through rational use of solid control equipment such as vibrating screen, sand remover, desilter, swirl separator and drilling fluid cleaner, drilling fluid can be reduced Dilution and dosage of treatment agent; Closed drilling fluid circulation system can prevent drilling fluid from falling to the ground and avoid seepage pollution.
Circulating fluid is indispensable in modern drilling. Except for a small amount of circulating fluid using gas and foam, most circulating fluids for drilling are liquids, so the circulating fluid used in drilling is called drilling fluid. Because the early drilling fluid was only a mixed liquid of clay and water and had almost no other chemical components, it was customarily called "mud" on the field. Drilling fluids play an important role in the drilling process. Its main functions are:
- Cleaning the bottom of the well
During the drilling process, the drill bit breaks the rock and generates a large amount of cuttings. These cuttings are removed by the circulating drilling fluid. If the cuttings cannot be removed in time, it will be repeatedly broken, which will affect the drill bit to continue drilling into the rock.
- Cooling and lubricating drill bits and drill strings
During the drilling process, due to the severe weight-on-bit load on the drill bit, the drill bit bearing and the working face of the drill bit became hot. At the same time, because the drill string constantly rubs against the borehole wall during the rotation process, not only heat is generated, but also the drill string is worn away and power consumption is increased, while the drilling fluid can take away the heat in time through the circulation to cool the drilling tool. It also acts as a lubricant, thereby reducing the side effects of friction.
- Form mud cakes to protect the well wall
Rocks deep in the formation are in a three-dimensional compression state due to pressure from the top and surrounding rocks. When the wellbore is drilled, the rocks around the wellbore must undergo compression from various directions to produce a stress increment value, that is, stress concentration. In this case, if the strength of the rock at the wellbore is not strong enough, it may cause the well wall to collapse. However, if a drilling fluid containing a weighting agent and low filtration loss is applied to the surrounding borehole wall, the stress on the rock will be reduced, thereby reducing the chance of "compressive collapse". However, the density of the drilling fluid must not be too large, otherwise it will cause "fracture fracture" of the rock, and then cause the leakage of the drilling fluid. In addition, the drilling fluid added with various additives will form a layer of mud cake on the well wall during the circulation process. The high-quality mud cake can not only protect the well wall from being washed away by the drilling fluid, but also reduce the leakage of drilling fluid to the formation.
- Controlling and balancing formation pressure
When drilling into a high-pressure oil (gas) layer, if the formation's oil (gas) layer pressure is higher than the pressure of the drilling fluid column, a “blowout” will occur and a drilling accident will occur. To this end, a drilling fluid of suitable density should be prepared so that the pressure of the drilling fluid column is equal to (usually slightly greater than) the formation pressure to ensure safe and rapid drilling. But the density must not be too large, otherwise the oil (gas) layer may be blocked.
- Suspended rock cuttings and weighting agents
During the drilling process, the velocity of the drilling fluid in the annulus of the wellbore cannot be too high, and the clear water has a poor suspension capacity due to its low density. To circulate the cuttings and weighting agents to the ground, various other additives must be added to the drilling fluid To increase its suspension capacity.
- Provide relevant geological data for the formation being drilled
By sampling and analyzing the drilling fluid flowing out of the ground, the lithology and oil and gas content of the drilled formation can be obtained.
- Pass water power to the drill
When drilling fluid flows from the water hole of the bit to the bottom of the well, it not only cleans the bottom cuttings, but also reduces the energy to the bottom of the auxiliary mechanical rock breaking. Jet drilling is a drilling process that uses the water power of the bit. Drilling practices at home and abroad have proven that jet drilling processes improve drilling speed and reduce drilling costs.
- Separation of drill cuttings on the ground
The solid phase particles dispersed in the drilling fluid are called solid phases in the drilling fluid. The solid phase in the drilling fluid is derived from drilling cuttings and artificially added to meet the drilling process requirements.
According to the role of solid phase in drilling fluid, it can be divided into two categories: one is useful solid phase, such as bentonite, chemical treatment agent, barite, etc .; the other is harmful solid phase, such as drill cuttings, inferior bentonite , Grit, etc. The solid control system of drilling fluid is to remove harmful solid phases, retain useful solid phases, or control the total solid phase content and particle size level in the drilling fluid within the range required by the drilling process to meet the drilling fluid performance. Requirements. It is also customarily referred to as mud purification on the field.Read More »
Keywords: deep well rig; solid control system; process flow; solid control equipment
In recent years, the development of medium and shallow wells in China has reached the middle and late stages. At present, the development of deep and ultra-deep well drilling rigs is concentrated, and higher requirements are imposed on the drilling fluid solid control system. The solid control system is from solid control equipment to drilling fluid circulation tank. Although the technology has been greatly improved and the process flow is becoming more reasonable, there are still many problems in the supporting of the solid control system, especially for the solid control of deep well and ultra-deep well rigs. The system is not mature enough. The author analyzes the advanced technology and development direction of the solid control system used in modern drilling, and combines the current status of the drilling fluid solid control system and the technical development status of the solid control equipment. Based on the actual process requirements of the drilling rig site, a set of research that can meet the production needs , And can produce better economic benefits of the 7000m deep well drilling control system.
1 Status and development of solid control equipment at home and abroad
1.1 Status of domestic solid control equipment
Domestic solid control technology was developed in the 1980s. In the past two decades, with the comprehensive implementation of jet drilling, optimized drilling, high-quality drilling fluids, and oil and gas layer protection technologies, the theoretical research and manufacturing processes of domestic drilling fluid solid-phase control equipment have been rapidly developed, promoted, and popularized. In terms of performance and life, domestic solid control equipment still has a certain gap compared with foreign countries in terms of materials, processing technology, processing accuracy and quality of supporting general-purpose equipment. At present, the mainstream configuration of domestic solid control is mainly based on 5-level solid phase control (screening-degassing-sand removal-mud removal-centrifugation).
1.2 Status of foreign solid control equipment
Foreign solid control equipment is represented by American companies such as BRANDT, SWACO, DERRICK, etc. The solid control equipment produced by them not only has good performance, stable work and long life, but also realizes equipment standardization, serialization and specialization. Quality and performance are first in the world. Foreign countries are equipped with solid control system equipment, focusing on optimized configuration and efficiency evaluation, and thus developed a drilling fluid solid phase control expert system. For example, a solid control system composed of 4 drilling fluid shakers and 2 dryers in the United States increases the processing capacity by 70% and is not easy to block. The separated solid particles are dehydrated by a dryer, and the dried particles are discharged. Dropped and recovered liquid is effective.
1.3 Development Direction of Solid Control Equipment
At present, foreign solid control equipment has matured, and standardized, serialized and specialized equipment types have been formed. Compared with foreign countries, the overall technical level of domestic solid control equipment still has a certain gap, and it is necessary to focus on the development of solid control equipment types, solid control equipment performance, life, and efficiency evaluation of the entire solid control system. In the future, the development requirements of international solid control equipment: energy saving, consumption reduction, safety and environmental protection. It mainly develops from the following six aspects: simplification and optimization of the solid control system; degassing and then screening; changing part of the processing to full processing; selective solid phase control technology; on-line drilling cuttings processing technology; drilling fluid repetition Use technology.
2 Design of deep well rig solid control system
With the deepening of oil and gas resources exploration and development, the definition of deep wells is also constantly changing. The current well depth of 6000 to 9000 meters is the category of deep wells. Here, a deep-well drilling rig for the exploration and development of oil and gas wells within a depth of 7000 meters of land drilling is developed from the main technical parameters of the solid control system, the configuration of the solid control equipment, and the process flow of the solid control system. Meter rig's solid control system.
2.1 Main technical parameters
(1) Determination of effective volume of drilling fluid circulation tank.
The effective volume of the drilling fluid circulation tank is the main technical parameter of the solid control system of the drilling rig. The finished drilling volume method is based on the volume of drilling fluid required to fill the borehole after completion of drilling as the minimum volume required for the drilling fluid system. This method assumes that no mud collection device is used and all drilling fluid is lost in the drill.
The nominal drilling depth capacity is 7000m, and the volume of the drilling fluid system supported by the drilling rig combined with Ф127mm (5in) drill pipe and 36T drill bit to reach the bottom of the well.
7000m × O.O127m3 / m = 88.9m³
36000kg ÷ 7754kg / m3 = 4.6m3
88.9m³ + 4.6m3 = 93.5m3
In the formula:
7754kg / m³—Density of drilling tool
O.O127m3 / m—Ф127mm (5in) drill pipe per meter of external volume fills the minimum volume of drilling fluid required for the wellbore to be 93.5m3, and an additional 50% is used as a safe volume, that is, 46.75m3, which is the minimum in use The volume is about 140m3, plus the reserve volume, usually the reserve volume is similar to the in-use volume, so the effective volume of the entire drilling fluid system is about 280m3, plus a 20m3 weighting bin, the total effective volume is 300m³. Requirement in "SYT6223-2005 Drilling fluid purification equipment supporting installation and use and maintenance"
The volume of drilling fluid circulation tank of 7000m rig is not less than 270m³, which fully meets the requirements.
(2) Main technical parameters:
Total volume: 353m3
Effective volume: 300m3 (excluding sand silo, etc.)
Mud tank body size (length × width × height): 11000 × 2800 × 2300mm (including skid height 300mm)
Transport size of mud tank (length × width × height): 13500 × 3000 × 2800mm
Number of mud tanks: 6 (inclined bottom structure)
Medicine tank: 1
Total installed power: ~ 650kw
2.2 Process flow of solid control system
2.2.1 Flow chart of drilling fluid purification process.
During the drilling process, the drilling fluid purification treatment is a solid-liquid separation of the drilling fluid by the purification equipment. It is currently divided into five levels, usually called five-level purification: vibrating screen → sand remover → desilter → mud centrifuge Machine → deaerator. For deep well drilling rigs, drilling fluids are all purified in five stages. After the mud returned from the wellhead is purified by a five-stage purification equipment, it is repeatedly pumped into the well for recycling by a drilling pump. The following is a typical process flow chart of a 7000m drilling rig solid control system (wherein from left to right, and from top to bottom are 5, 6, 1, 2, 3, and 4 tanks).
2.2.2 Main supporting solid control equipment.
The main supporting solid control equipment is shown in Table 1.
|Vacuum deaerator||1 set||null|
|Drilling fluid shaker||3 sets||null|
|Drilling fluid centrifuge||1||LW450 × 1000N2|
|Sand pump||6 units||55Kw|
|Shear pump||1 set||55Kw|
|No pump||1 set||11Kw|
|Jet mixing funnel||3 sets||Barite feeding: 300kg / min|
|Swirl mixing funnel||1 set||Bentonite feed: 150KG / min|
|Mud Mixer||11 units||15Kw|
|Mud Mixer||3 sets||7.5Kw|
|Mud Mixer||1 set||5.5Kw|
|Mud gun||14 only||Pressure: 6.4Mpa|
2.2.3 Composition of drilling fluid purification cycle process.
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