Storm water can be reused for fluid makeup water, although the drilling personnel may not like it much. It can also be used for rig wash water. Rig wash water (which falls into the same ditches as the storm water) should be reused until it is too dirty to be used as wash water. It is surprising how many times wash water can be used effectively.
The recommended design stress levels and verification testing procedures contained herein deal with structural failure. Structural failure is defined as fracture or excessive material yielding. Design stress levels and testing procedures are independent of coupling design or method of makeup.
In addition to the stress distribution verification test prescribed in Section 3.6 above, three types of full-scale design qualification tests are recommended a load rating test to establish classification of the particular coupling design, a makeup test to demonstrate the ability of the coupling to be correctly made up in the field and the repeatability of proper make-up, and an internal pressure test to check pressure integrity and seal effectiveness. Standard makeup tools should be used to apply preload to the coupling. Strain gage readings from selected points on the coupling should corroborate the values used in the analysis. Measured preload stresses should meet or exceed the minimum required preload stresses over at least ten successive make-up sequences.
Non-inhibitive fluids are simple and inexpensive. Their composition will vary depending on the requirements of the local lithology, type of makeup water, hole size, and anticipated contaminants. These muds have definite limitations which become evident when drilling dispersive formations, encountering contaminants and high temperatures, or increasing fluid density. Each of these situations may require converting to another type of fluid which is more adaptable to these conditions.
BEN-EX muds are generally not converted from an existing fluid, but prepared from scratch. First, clean the pits and build volume with fresh water. The makeup water should be treated with soda ash to remove hardness. Add 0.25 lb bbl soda ash to remove calcium from makeup water. The sodium polyacrylate is added to reduce fluid loss. The pH of the water should be adjusted with either soda ash or caustic soda. To obtain proper viscosity bentonite and BEN-EX through hopper at the rate of one 2-lb bag BEN-EX for each 5 100-lb bags bentonite until reaching a sufficient bentonite concentration of 10-14 lb bbl. Barite can be used to increase density however, BEN-EX must be added along with barite additions. One 2-lb bag of BEN-EX must be added only with each 40 100-lb bags of barite when increasing density. Also, add 0.7 gallons of water for each sack of barite. The upper limit for mud weight for this type of mud is usually 14.0-14.5 lb gal.
The calcium ion is a major contaminant of water-based drilling fluids. Calcium can enter the mud as part of the makeup water or formation while drilling cement, anhydrite or gypsum. Calcium contamination drastically changes the nature of freshwater, clay-based systems. The calcium ion tends to replace sodium ions on the clay surface through a base exchange. The bound layer of water on the clay platelets is reduced, resulting in diminished hydration or swelling characteristics. The effects of calcium contamination on deflocculated muds are increased fluid loss, yield point and gel strengths. Calcium contamination originating in makeup water or formation water is usually treated with soda ash. Approximately 100 mg L of Ca++ should be left in the system to react with carbonate ions.
Conversion - Lignite Lignosulfonate (Deflocculated) Muds are quite flexible in their makeup, conversion, and maintenance. Care should always be taken so that conversion to a lignite lignosulfonate mud is not initiated before hole and mud conditions dictate. When converting to a lignite lignosulfonate mud, the volume of solids should be lowered by dilution with water or by mechanical removal prior to the conversion. Calcium ion hardness should not exceed 200 mg L. If hardness is greater than 200 mg L, treat with soda ash prior to making the conversion. Bentonite treatments, if needed, should be added prior to adding the lignosulfonate otherwise, it will require more bentonite to achieve desired flow and filtration properties. The pH should be in the range of 9.5-10.5 and the PF should be 0.2-0.8 cm3. Pilot test results will determine the correct caustic soda or caustic potash treatment. Lignite and or lignosul-fonate and caustic soda treatments should be added gradually and...
There are several methods commonly used or available to determine the presence of H2S in drilling fluids. Gas detectors or monitors are used on drilling rigs to detect unreacted H2S gas at the surface. The Hach test is used to detect H2S in the acid form, or as soluble sulfides in the makeup water, filtrate or mud. The Garrett Gas Train also analyzes the soluble sulfides in the filtrate of the mud. In addition, both tests can also determine the total sulfides, both soluble and insoluble, in a mud. It is important that the engineer have a complete understanding of the testing procedures and of the test results being reported.
Although additives and concentrations are essentially the same as for Saltwater Muds, Brackish-Water Muds generally are not as difficult to maintain because of their lower makeup water salinity. However, because of the nature of brackish water environments, both organics and bacteria may cause increased consumption of additives. Lignite - Lignite is added to improve HTHP filtration control, but may not be an effective deflocculant, depending on makeup water quality.
Hydrogen sulfide is sometimes associated with a gas kick or bleed-in. Other sources are makeup waters and microorganisms. Although hydrogen sulfide is relatively noncorrosive in the absence of moisture, the gas becomes corrosive if moisture is present. In the presence of CO2 or O2 and water, hydrogen sulfide becomes severely corrosive due to the driving voltage increase of the corrosion cell. Normally, when H2S corrosion is a severe problem, one of these other gases is present. The chemical mechanism of this type of corrosion can be simply, though not completely, stated as
A polymer is a large molecule composed of a relatively small molecules called monomers (8 units) bonded together. The molecular weight of polymers range from a few thousand to several million molecular weight units. Polymers can have thousands of repeating units. The lower molecular weight polymers serve as deflocculants whereas, the high molecular weight molecules serve as viscosifiers and flocculants. The two major mechanisms for manufacturing polymers are condensation, which alters the makeup of the repeating units, and addition which utilizes the presence of a double bond in the reacting unit to form a long chain. The addition process will generally yield higher molecular weight polymers than will condensation. The condensation process produces a polymer in which the repeating units contain fewer atoms than the monomers from which they were formed. Frequently, water is formed as a by-product of the process. The process requires two or more compounds which react chemically and does...
This recommended practice pertains to the design, rating, and testing of marine drilling riser couplings. Its purpose is to serve as a reference for designers and those responsible for the selection of marine riser couplings. Capacity ratings are delineated to facilitate the grouping of coupling models according to their maximum stresses developed under specific levels of loading these capacity ratings enable grouping of coupling models independent of manufacturer or method of makeup. This recommended practice relates directly to API RP 2Q, which pertains to the design, selection, and operation of the marine riser system as a whole.
In thermal desorption, oily cuttings are fed to a heating unit. Many types of heating units exist, but the purpose is to efficiently transfer heat to the drilled cuttings to where oil and water are driven off. The water and oil are separated. Depending on quality, the recovered oil is used to further fuel the thermal desorption process, as makeup fluid for the fluid system or it can be sold to industries needing boiler fuel (cement kilns and power plants).
Tool joints Connectors for the bit, drill stem, etc. These consist of tapered, coarse threaded connectors machined on the ends of the tools. The thread design allows easy makeup, and the necessary tightness is obtained from the metal-to-metal fit at the flat shoulders of the joint. Proper tightness of these joints is essential to prevent the severe drilling vibrations from unscrewing the tools.
Salt, NaCl, contamination may be a result of salty makeup water, drilling salt stringers, or saltwater flows. Saltwater-based drilling fluids are used when salt is drilled in large quantities or where salty makeup water is used. In saltwater muds, salt is not a problem however, in freshwater muds salt becomes a contaminant.
Water quality is important in formulating a bentonite-water mud. Chlorides (Cl-) and hardness (Ca++ and Mg++) in the makeup water interfere with the hydration of the bentonite. Calcium ion concentration should not exceed 150 mg L. If greater than 150 mg L, it should be treated out with soda ash. Treatment with 0.1 lb of soda ash per barrel of water will remove approximately 100 mg L of calcium ion. Magnesium hardness, on the other hand, is treated out with sodium hydroxide. At pH of 9.7 magnesium ions will have all been reacted with sodium hydroxide to precipitate Mg(OH)2. Chlorides, however, cannot be treated out of the makeup water. Less than 5000 mg L chlorides will not seriously hamper hydration of commercial bentonite. When there is more than 20,000 mg L chlorides, bentonite hydration is essentially prevented. Adding fresh water to reduce the chloride concentration becomes necessary to allow hydration.
Clear water varies in salinity from fresh to saturated brines. Water selection and salinity will depend upon available makeup water or salinity required to drill specific formations. Clear water fluids are Newtonian and thus, require high annular velocities for hole cleaning. Occasional viscous sweeps (small batches of high viscosity mud) are pumped around to clear the hole of cuttings as needed. Caustic soda or lime is usually added for corrosion control.
Quick-connect couplers simplify the task of connecting and disconnecting down-hole tools, speeding the process and reducing the risk of accidents during tool change. Drill pipe links the drill rig to down-hole tools, transmitting engine horsepower to them for thrust, pullback, and rotational torque. Drilling fluid is delivered to down-hole tools through the string of the drill pipe guidance-system components are attached to the drill string behind the drill bit. When the pilot hole is finished, the pipe pulls reamer and product through the hole to complete the installation. HDD pipe must withstand tremendous forces generated during the drilling and pullback. Each length of pipe must be flexible enough to be steered effectively, yet have enough rigidity not to break or become permanently bent. Connections must be durable to resist wear from repeated makeup and breakout.
Electrolyte makeup will have a similar effect on the water associated with a clay platelet. This water layer, also called the electric double layer, will be forced to shrink if the clay is immersed in a fluid with a high cation concentration. While this effect is greater with divalent cations such as calcium or magnesium, high concentrations of sodium will have the same effect. This shrinking of the electric double layer will allow the clay particles to approach each other more closely. They may reach the point when the physical attraction between the clay particles exceeds the repulsive force of the electric double layer at which time the clays will flocculate or clump together. It is difficult sometimes to understand why cations added to a bentonite water slurry will cause an increase in viscosity, while bentonite added to an electrolyte solution will provide little if any viscosity. In a freshwater bentonite slurry the clay platelets are dispersed and kept apart by the electric...
Saltwater Muds Muds ordinarily are classified as saltwater muds when they contain more than 10,000 mg L of chloride. They may be further classified according to the amount of salt present and or the source of makeup water (see Table 1.3) Saltwater muds may be purposely prepared, or they may result from the use of salty makeup water, from drilling into salt domes or stringers, or when saltwater flows are encountered. Saltwater muds include the following types. Seawater or Brackish Water Muds These muds are prepared with available makeup water, both commercial and formation clay solids, caustic soda, and lignite and or a lignosulfonate. CMC is usually used for fluid loss control, although concentration of lignites and lignosulfonates are also often used for this purpose. Viscosity and gel strength are controlled with caustic soda, lignosulfonate, and or lignites. Soda ash is frequently used to lower the calcium concentration. CMC or lignosulfonates are used for water loss control, and...
Saltwater muds are often prepared from fresh water or bentonite-water muds. These muds normally contain low solids concentrations, have low densities, have minimal chemical treatment, and possess low viscosities and high fluid losses. Saltwater muds may be prepared intentionally with salt to drill troublesome shale sections. They are used as an inhibitive mud to decrease dispersion and viscosity build-up from drilled solids. These muds may range from approximately 25,000 mg L salt up to nearly saturation. Produced brines are commonly used in workover and completion operations. Swelling of formation clays or shales are reduced. They are also used as low solids fluids to control pressures that are normally encountered in workover and well completion operations. Seawater can also be used to formulate a saltwater mud. Frequently in offshore drilling, seawater is used as the makeup water to avoid the expense and problems of transporting fresh water to the wellsite. Typical seawater...
The shank seal and shoulder provide the fluid seal between the bit and the drillslring, The threads will not form a pressure-tight seal and will result in a washout if the bit is not made up properly. It is important, therefore, to ensure that the seat and shoulder are clean and not scarred prior to bit makeup.
While the coupling design load provides a means of grouping coupling models independent of manufacturer or method of makeup, it does not include all loads affecting coupling design. Appropriate auxiliary loads as defined in Section 3.2 should also be included in the evaluation of coupling designs.
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