Make Money in the Recycling Business
Recycling these fluids is inexpensive and can save a large amount of fluid. Preplanning was an integral part of the Louisiana project. Thinking about the operation and developing a plan to handle the waste streams always pays off. If you are going to dump the sand trap, then where will that waste stream go (especially if your pits are aboveground) How will you handle the low-contaminant but large volume associated with surface hole and keep it separated from the oil-based fluid or highly treated fluid later Once the location is built, it is usually too late to consider these things.
The drilling-fluid program should address environmental issues concerned with the discharge of drilling fluid, products, and removed solids. Personnel managing the solids-separation equipment must be very familiar with this part of the drilling-fluid program and have a good understanding of governmental regulations and operator requirements. Many drilling operations have strategies in place for drilling-fluid recovery and will have established some general guidelines for the disposal of materials classified as waste. However, situations can arise that present the engineer managing the solids-control equipment with the issue of whether to discard or recycle some types of waste and how to do it. If disposal costs are not a factor, then all waste can be disposed of and treated, if necessary, onsite or sent to a processor offsite. However, if it is possible to recycle some of the products to the mud system, it may prove economical to do so Hollier et al . Table 2.4 contains some general...
The Water Resources Division of the U.S. Geological Survey sometimes contracts for air-rotary coring in possibly contaminated or known contaminated lithologic environments. Special coring procedures are used, such as grouted insurface casing using drive-core or other samplers for obtaining cores of unconsolidated interbedded sediments and using only wire-line-coring methods, to prevent smearing or downward contamination of the hole that could occur if conventional coring (tripping in and out of the hole) methods were used. For discussions of these precautionary methods, see Hydrology of the Solid-Waste Burial Ground, as Related to the Potential Migration of Radionuclides, (Burgus and Maestas, 1975).
Because of the information available on drilling fluid toxicity in the marine environment, one can infer that disposal of drilling fluids and solids offshore is environmentally safe if approved by the EPA. Some EPA regions do not allow any discharges overboard, others require bioassay information for the drilling fluid prior to discharge, and some allow almost any discharge into state or federal waters. Many industry experts expect that sooner or later, the Federal EPA and related agencies will require all discharges to be non-toxic or hauled to shore for disposal. Moreover, it appears that state waters will follow suit. Thus, the ultimate fate of waste material generated in offshore drilling operations will need to be handled according to onshore disposal regulations.
There are several methods used to determine economic performance. This appendix describes a method to compare the cost of dilution versus mechanical removal. It utilizes the concept of a dilution factor (the amount of mud required to maintain a given solids concentration for every barrel of solids that remain in the mud) to determine dilution requirements. This method may be used to determine economic efficiency of any type of solids control equipment. Note Effluent is defined as the process stream returned to the active mud system. The underflow is defined as the waste stream removed from the mud system and discarded.
Another seemingly promising technology has been conversion of the waste material into bricks or other construction slabs or blocks. Again, the technology has not proven reliable or economical if leachate standards are met. Salt readily leaches out of bricks and concrete, as can be seen in any tropical climate (salt is used to speed up setting time in building construction). In Venezuela, a wall was built of concrete blocks as part of an encapsulation solidification process. Years later oil could be seen and smelled at considerable distance from the wall. Unfortunately, this result is the rule rather than the exception.
Treatment techniques differ from disposal techniques in that they modify or separate the properties of the waste, but the waste must still be placed somewhere. In burial, discharge, land application, and injection, the waste is placed on the land, in the sea, or deep in the earth. Treatment techniques are aimed at removing oil, reducing the mobility of contaminants, or otherwise modifying the properties of the waste material.
Shown below is a cutaway view of the A-24. Mud from the sump or from the return circulation is introduced into the A-24 either lull strength, or diluted with water if this is desirable. It enters the Concentrator at (A) here it is suhjected to high centrifugal force which separates the heavier solids from the lighter liquid in separation chamher (B). The concentrated solid underflow occurs at (C) waste material leaves machine through overflow port (D).
Each level of the food chain contributes waste products, and every organism that is not eaten eventually dies. In recycling this organic material, an important role is played by a diversity of bacteria. The two principal types are those that live in aerobic (oxygenated) environments and derive their energy by oxidizing organic matter and those that live in anaerobic (reducing) environments by taking the oxygen from dissolved sulfates and organic fatty acids to produce sulfides (such as hydrogen sulfide) and hydrocarbons. Although aerobic decay liberates certain hydrocarbons that some small organisms accumulate within their bodies, the anaerobics are more important in the formation of oil. If the process of aerobic decomposition continues indefinitely, all organic matter, including hydrocarbons, is converted into heat, water, and carbon dioxide - the raw materials that photosynthetic plants use to make their carbohydrate food. For an accumulation of petroleum to be formed, the supply...
If injection is to be used, then slurry must be made from the fluid and cuttings. The fluid and waste fluids are collected into slurry tanks to make the slurry. These slurry tanks are circulated with special slurry pumps designed to break up particles into natural grain sizes. If more fluid is needed because the slurry is too thick, then seawater can be added. The fluid may be too thin if excessive amounts of water are collected in the waste stream or if the mixing is insufficient. Frequently a shaker is used prior to the slurry tanks to prevent large particles or junk from entering the slurry tanks. In addition, there is a suction line screen to protect the pumps. There are usually two or three slurry tanks of 100-to 150-bbl capacity. This large volumetric capacity may be needed to handle large hole drilling.
Selecting a drill rig with an adequate fluid capacity is a key factor for supporting the production rate and avoiding stuck drill-pipe conditions. It is also important to properly match the fluid mixing and cleaning equipment with the drill-rig fluid capacity. If the mixing and cleaning equipment is undersized, the drill rig cannot reach optimum production rates because the drilled solids cannot be pumped out of the bore hole and cleaned as fast as the drill is capable of advancing. Likewise, a smaller drill rig can be used for rock drilling with a down-hole motor if an auxiliary pump and recycling system is used to enhance the fluid handling capability.
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