5. The functions of drilling mud, and how their properties are modified to suit downhole conditions Discussion of the problems the mud engineer has in selecting a mud for a HPHT well. Introduction The drilling mud plays a critical role in any successful drilling operation. It must be carefully optimised and managed to ensure the safety of the drilling operation and to minimise hole problems. A failure in the mud design can lead to significant losses in terms of time and cost as a result of problems such as stuckpipe, kicks and blowouts. Depending on the continuous phase, drilling mud can be classified into water-based and oil-based. Drilling mud has the following functions: i. The drilling mud is used in controlling the hydrostatic pressure by keeping it higher that the formation pressure. ii. The mud is used to extract cuttings from the hole. The effectiveness of this function is contingent on the yield point (YP) property of the mud. iii. A lot of heat is generated during drilling due to friction and the mud works to cool and also lubricate the drill bit and drillpipe iv. To keep the integrity of the hold by preventing caving. The drilling mud forms a mud cake on the walls of the formation which stabilises it. v. Helps to release the drilled cuttings at the surface vi. Help minimise formation damage by maintaining a low fluid loss into the formation vii. Assisting in formation evaluation viii. Keeps cuttings in suspension when circulation has stopped The properties of
Hydraulic fracturing is also known as “fracking” is a technique which involves drilling down, then horizontally as far as 10,000 feet below the surface to release natural gasses stored in the sedimentary rock known as Shale. The channel is then encased with concrete or occasionally steel to allow millions of gallons of water to be injected into the wellbore. Most water used in fracking comes from surface water sources such as rivers, lakes, or other accessible bodies of water nearby. Not only is there water being funneled into the wellbore, but also a mixture of sand and other chemicals. When the high-pressure mixture is injected underground it fractures the Shale around the wellbore and creates fissures. The fissures are then held open with
Once the well reaches the right depth, it turns right or left and becomes horizontal. This is called the kick off point. The horizontal section can span anywhere from 1,000 to 6,000 feet. The drill is removed but the surrounding steel casing remains. These steel casings are meant to protect the groundwater and the surrounding area from any potential leakage during the fracking process. Down at the horizontal section of the well, little holes are punctured through the steel in thousands of spots. Then, a water solution is pumped at a extremely high pressure down the well. This causes tons of cracks and fissures in the rock. Additives and sand in the water mixture hold the cracks open, allowing oil to escape and be brought up to the surface.
Additionally, drilling sites are always located in inaccessible areas that cannot provide a comfortable working condition. Therefore, it could contribute to a lower level of operational productivity.
drilling process also uses various chemicals to extract the oil and natural gasses. Since fracking
“For Angelica Gallegos, the worst part has been going without a shower for five months” (Source 2). “Juan de La Cruz works on this rig 12 hours a day, seven days a week, carefully guiding the drill bit. He’s standing in a little hut next to the drill hole that they call ‘the dog house.’ It’s where workers keep a log of the layers of sand and clay, they find, collecting samples every ten feet as the drill probes deeper” (Source 3).
With the age of constant industrial and technological growth has come the necessity for not only cost effective and efficient methods for industry, but also the need for obtaining fuel for the machines that make the modern world possible. Oil has become as precious a commodity as gold, if not more so; its attainments constantly driving the world's largest businesses and governments across the world into action. Naturally, a "quick-fix" solution to this problem is constantly sought after by oil companies wishing to provide oil on a massive scale. One of these drilling methods is known as induced hydraulic fracturing (also known as fracking).
Fracking is the nickname for Hydraulic fracturing and a type of drilling that has been used since 1950. Today, fracking is the United States most reliable source of natural gas and oils. Fracking consists of safely tapping shale rock and other tight-rock formations by drilling 1-2 kilometres or more below the surface before slowly turning horizontal and then continuing several thousand feet more. One fracking site can have a number of wells. Once the well is drilled, the drill is removed and the well hole is made solid.
After it has drilled a while deeper another casing is placed to further protect the groundwater from the natural gas and oil which is to be soon produced. Vertically the drill may dig as deep as 4,500 to 7,500 feet.
extending the cracks created by the perforating gun. The sand keeps the fractures open once
- Mudjacking uses a cement-based material to fill voids and lift the slab. Because of its thickness, the material creates a burden on loose soil and causes future settlement.
Fracking, is drilling over 5 thousand feet into the ground then turning it at a horizontal angle and continuing several thousand feet more. A single surface site can contain several wells. When the well is drilled, and cased then cemented.(1) small fissures are made in the horizontal part of the pipe where a mixture of 90% water and 9.5% sand and .5% additives is pumped at high pressure to creates cracks in the rock that are held open by the sand. Then the additives help create less friction, stop pipe corrosion and help break the rocks up better.
Class II is the selection given by the EPA for wells that inject below the Underground Source of Drinking Water (USDW) and are consider deep wells, unlike Class V, that are shallow disposal wells such as septic tanks that dispose non-hazardous fluids underground. These salt water disposal wells are used to dispose the produced water from oil and gas extraction activities permanently. The produced water is also called brine. This produced water is extremely saturated with salt, has a high number of total dissolve solids, contains residuals from crude oil, and may contain other chemicals used during the production process. There are other injection activities in this area that inject produce water in the Birds Nest aquifer, which is the enhance recovery activity. The enhance recovery activity injects produced water in the same formation that the oil companies are extracting the oil and gas. These enhance recovery wells will not be used in this study since the water injected will stay in the formation temporary. The produced water from salt water disposal wells will stay in a different formation permanently and can pose a threat to the area and nearby aquifers. The average depth of the injection zones in the Birds Nest average from 3,000 feet below surface level to 10,000 feet below surface level. The average depth of the USDW in this area is 300 feet below surface level. If there is an aquifer that is used or will be used in the future for the purpose of drinking water, then the constructions of these wells need to be rigorously engineered to protect this source of drinking water. These injection wells contain two to three layers of cement to make sure there is no migration of the injected fluid. The permits for these well state that extensive logs and test needs to be done regularly to ensure the mechanical integrity of
When the solution of water, chemicals, proppants, and sand leak into the ground, it can contaminate ground water (Fracking Fury). The mix of chemicals the workers use can be very toxic to any living thing. The mix does not only poison the water, but contaminate it so severe that it cannot even be cleaned in a water treatment plant (Fracking Explained). To further the chance of this happening the drillers, by law are required to leave a variable amount of the toxic liquid in the hole and seal it up (fracking good idea?). Leaving it miles deep in the earth to poison our ground water. The chemicals do not only pollute the water we drink, but also the air we
The issue of whether offshore oil drilling is a safe operation or not has been arguing for a long time in the United States. ( SPE International, N.D.) Drilling on water started in early 1930s in Louisiana by shallow-draft barges. Nevertheless, the first oil well on water was drilled in 9th of September, 1947 by Kerr-McGee’s unit Tender Assist Drilling (TAD) in the Gulf of Mexico (SPE International, N.D.). A year after year, oil companies used more and more sophisticated equipment to drill on water, but the number of spilled accidents has been rising since 1964 (Ivanovich, and Hays, 2008). After all, while
When steam is injected to the formation a steam chamber around the well is created [3]. The pressure of the steam should be lower than the fracture pressure of the rock mass to prevent the deflection of the rock [4]. Steam injection will go on for months during which the steam chamber expands and the viscosity of the bitumen decreases. This will cause the bitumen to flow down under gravity towards the production well. The produced oil is then pumped to the surface. Surface facilities are then used to separate the water