Drilling is about connecting the subsurface geoscientist’s dream to the surface engineer’s reality. A well is “drilled” by creating a borehole 3.5 to 36 inches in diameter into the earth using a drilling rig. After drilling the hole, steel pipe (casing) is placed in the hole, and secured with cement outside. This casing provides structural integrity to the newly drilled wellbore in addition to isolating various zones from each other and from the surface. With these zones safely isolated and the formation protected by the casing, the well can be drilled deeper with a smaller bit, and also cased with a smaller size casing. Modern wells often have 4-7 sets of subsequently smaller-hole sizes drilled inside one another, each cemented with casing. To drill the well, the drill bit, aided by rotary torque and the 
compressive weight of drill collars above it, breaks up the formation. The drillstring, to which the bit is attached, is gradually lengthened as the well gets deeper by adding 30-foot joints of drill pipe at surface. Usually joints are made up into stands of three. Drilling fluid (mud) is pumped down the inside of the drillstring and exits at the drill bit and aids to break up the rock, keeping pressure on top of the bit, as well as cleaning, cooling and lubricating the bit. The cuttings generated by this drilling action are brought to surface by the drilling fluid as it circulates back to surface outside the drill pipe. The mud is directed over shale shakers which separate out the cuttings over screens allowing the clean mud to return back into the mud pits or storage tanks for recirculation. Analyzing the returning cuttings and monitoring various drilling mechanics data (e.g., pit level) are imperative to identify the potential inflow of formation fluids (a “kick”) so that that it can be mitigated with well control measures to prevent a blowout. This entire process is managed using a drilling rig, which contains the necessary packages to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations.
compressive weight of drill collars above it, breaks up the formation. The drillstring, to which the bit is attached, is gradually lengthened as the well gets deeper by adding 30-foot joints of drill pipe at surface. Usually joints are made up into stands of three. Drilling fluid (mud) is pumped down the inside of the drillstring and exits at the drill bit and aids to break up the rock, keeping pressure on top of the bit, as well as cleaning, cooling and lubricating the bit. The cuttings generated by this drilling action are brought to surface by the drilling fluid as it circulates back to surface outside the drill pipe. The mud is directed over shale shakers which separate out the cuttings over screens allowing the clean mud to return back into the mud pits or storage tanks for recirculation. Analyzing the returning cuttings and monitoring various drilling mechanics data (e.g., pit level) are imperative to identify the potential inflow of formation fluids (a “kick”) so that that it can be mitigated with well control measures to prevent a blowout. This entire process is managed using a drilling rig, which contains the necessary packages to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations.
A drill bit is the cutting or pulverising tool used during the drilling of a well to bore a hole through subterranean formations. The drill bit is attached to the lower end of the drill string, which provides mechanical energy in the form of weight on bit and torque, and hydraulic energy via the circulating drilling fluid. There are two broad classes of drill bits: fixed cutter bits and rolling cutter bits.
There are many types of fixed cutter bits: Polycrystalline Diamond Compact (PDC) Bits, Diamond Impregated Matrix Bits, Natural Diamond Bits, TSP Bits, Core-Ejector Bits, Bi-Center Bits, Casing/Liner Shoe Bits, Hammer Bits.
There are also many types of rolling cutter bits: Tungsten Carbide Insert (TCI) Bits, Milltooth Bits, Monocone Bits, Two Cone Bits
Drilling fluid or drilling mud, as it is commonly called, refers to mud or similar fluids that are a critical component of the well drilling process. While a well is being drilled, drilling fluid is continuously circulated from tanks at the surface, pumped by the mud pumps down the center of the drillstring. It exits the drill string through nozzles in the bit and returns to surface in the annulus between the outside of the drillstring and the hole that has already been made. At the surface it is processed to remove cuttings so that it can be pumped down the drill string again.
During this cycle, the drilling fluid serves many puposes, such as:
- Provides primary well control via the pressure created by the fluid gradient throughout the wellbore. If the fluid gradient is greater than the pressure of the oil or gas in the formation, hydrocarbons are prevented from unexpectedly entering the wellbore and coming to surface (a blowout).
- To provide support for the formation being drilled through so it doesn’t cave into the wellbore during the drilling operations.
- Lubricates and cools the bit and drillstring to reduce the amount of torque required to drill, as well as reducing wear on these components.
- Transports formation cuttings (drill cuttings) from the bit on the bottom of the wellbore up to the surface. This both removes the cuttings from the hole and allows them to be collected and used for formation evaluation analyses.
- Powers downhole equipment such as mud motors or MWDs, which convert the fluid’s pressure into other forms of energy such as rotation or electricity.
- Removes partially-fractured cuttings from the bottom of the wellbore, helping the bit cut through the formation faster.
- It must have gelation property so that it must support cuttings in case of no-circulation condition. Otherwise drill bit may get stuck.
- It should be environment friendly.
- It should be non-toxic and should not harm the working personnels.
Drilling fluid have evolved and continue to evolve within the E&P industry. In 1901, the discovery well of the Spindletop field on the Texas Gulf Coast marked the first use of the rotary drilling method still in use today. The Spindletop discovery well also introduced the use of drilling fluids. The first “modern” drilling fluid was created by running a herwas d of cattle through an earthen slush pit. Drillers used the resulting muddy water to control a potentially catastrophic quicksand problem. This unusual event gave drilling fluids their well-known nickname: “drilling mud”, or more simply “mud”. The new-found capability of drilling soft and unconsolidated formations rapidly helped spread the use of rotary drilling. Hole stability was achieved by plastering the hole walls with clay materials contained in formation cuttings or added to the mud at surface. Generally overlooked until years later, however, was the contribution of mud weight (density) to hole stability and, more importantly, to subsurface pressure control. In the early 1920s, barite (ground barium sulphate ore) was selected as the best mud-weight additive for use in pressurised formations. Barite was inert in water, not too abrasive, and readily available. Other important mud additives followed. Bentonite clay was recognised for its superior mud-making properties and became the primary additive for viscosity, solids suspension and filtration control. Increasing demands for hydrocarbons promoted new drilling challenges. Drilling-fluids technology kept pace. Considerable resources were allocated to improve the understanding of mud chemistry, to apply new testing methods, to refine field procedures, and to develop special additives to prevent and correct mud-related problems. Innovative mud systems, some radically different, emerged to satisfy ever-expanding technical requirements and lower costs. Air and natural gas were exploited to increase drilling rates in hard, dry formations. Natural and synthetic polymers became the foundation for entire families f drilling fluids. Mudss based on (synthetic) oil instead of water, originally introduced to minimise formation damage, later evolved into high-performance systems suitable for use in the most hostile drilling environments. High-performance, environmentally friendly synthetic-based mud systems, introduced in the early 1990s, have arguably made the biggest impact in this respect. Despite unit costs two to eight times higher than conventional fluids, impressive performance/cost ratios and environmental acceptability helped establish synthetic-based fluids as the best choice for some critical wells. Today’s rapidly changing technical and business climates have further intensified the focus on drilling and completion fluids and their role in well construction. Currently, the performance of non-conventional wells, including horizontal, multilateral, extended-reach, deepwater, slimhole and smart designer wells depends, more than ever, on the overall effectiveness and efficiency of the drilling fluid. Special alliances involving operators, rig contractors, mud companies, and chemical suppliers continue to open new avenues for cooperative research. The steer lies with operators, specifically the well fluids engineers, and it is here that the fundamental understanding of mud and completion systems must be sought.
Any requirements, please contact with us freely!
Tangshan Aojie Petroleum Machinery Equipment Make Co., Ltd (Short for: OGEM Solids Control)
Address: NO.2 Jingxi Road,Lunan District,Tangshan city,Hebei province,China
Tel: 86-315-8676484
Fax: 86-315-2648099
Zip Code: 063000
Email: ogem2@ogemsolidscontrol.com
Website: http://www.ogemsolidscontrol.com/
Need any lateast news about the Hydrocyclone desender or other oilfield equipment,please enter in our website. WELCOME!!!
没有评论:
发表评论