Category Archives: Drilling fluid

Type of drilling fluid and the additives used in oilfield

Fluids play an integral role in oil and gas exploration and production. When a new well is drilled, some form of fluid is needed. The base of this drilling fluid, or mud, can be freshwater or saltwater (brine) or it may be an oil- or synthetic-based liquid.

The type of fluid and the additives used are determined in part based on the composition of the rock being drilled into.

drilling fluid

Cost and environmental impact are also considerations. The mud may also be modified as drilling progresses and the underground environment changes.

Ideally and increasingly, this fluid is recycled during drilling. To facilitate reuse, cuttings are allowed to settle out in a pit and the resulting liquid is pumped back to the wellbore.

Water is often a natural byproduct of the drilling and production process. Water may be trapped underground along with the oil and gas. Sometimes this produced water is incorporated and used in the drilling process.

Assortment of solids phase in oil drilling fluid

According to the different characteristics, there are different classification methods of the solid phase in drilling fluid.

  1. According to the role of solid phase in the drilling fluid, it is divided into useful solid and harmful solid phase.
  2. The solid phase is divided into high density solid phase and low density solid phase according to the density of the solid phase. High density phase is the weighted materials based on the drilling process requirements to increase the density of the drilling fluid, low density phase including the bentonite and treatment agent that required by configuration of the drilling fluid, and there are cuttings.drilling fluid7
  3. By whether solid phase and liquid phase is reacted, the solid phase in drilling fluid is divided into active solid phase and inert solid phase. The solid phase that can react with liquid is called active solid phase, and can not react with liquid is called inert solid phase. The former such as bentonite, clay and shale, etc, or such as limestone, granite, barite etc.

Drilling waste water treatment technology

For offshore drillings, one of the biggest drilling waste is sewage which grows out of drilling fluids, rain, water used to wash bits and cooling water. Usually, the under-treated sewage weighs 30 times the well-bore volume. Therefore, sewage minimization is a very vital part in the whole waste treatment.

However, as the easiest waste resource to be reduced, water can be reduced in such ways as below:

One-way cooling system can save water and seal it inside the system while eliminating cooling water, braking water and sealing water to achieve water recycling. It is proved that it is not pricey to recycle the water and is able to save a large amount of liquids.

The reason that rain can be recycled is the correlation between drilling fluids and water. Rain is applicable in washing drilling equipment. The water used to wash drilling equipment can flow into water tank just like rain and should be recycled till it cannot function any more. It will be surprising to see how many times they can be reused.

The dirtiest water ( such as, deserted drilling fluids ) can be applied to wash the panel. Desander and filter can produce massive deserted drilling fluids( usually there is one portion of solid phase in 2 or 3 portions of fluid phase ). They can be used to wash drilling mud tank. And shale shaker and decanter centrifuge also need washing water. Water used to clean panel do not need purifying since it is not necessary to wash away solid phase and liquid phase with clean water. It will be very difficult to separate them during treatment procedure.

It is necessary to produce sewage. It is quite expensive to treat sewage, so vacuum device is preferable to washing water here. A gun-shaped controller with tube is a good idea. The tube falls and automatically closes the connection to disconnect the controller. Drilling operators prefer high-pressure, small-volume washer due to the less labor intensity, better washing effects and reduced sewage volume. Generally speaking, both the vacuum device and washer are put into use when treatment is not costly. However, the gun-shaped controller will offset the cost.

Different approaches can be conducted to separate and treat waste, for instance, water-based waste and oil-based waste can not blend until being managed together. During the operation, fluid from drilling mud pits should be reinjected so as to flow into spare drilling mud pits.

Advantages and disadvantages of oil based drilling fluid

Oil based drilling fluid is the drilling fluid which use oil as a continuous phase. It is divided into whole oil based drilling fluid and oil water emulsion drilling fluid. Water is a useless component in the whole oil based drilling fluid, and its water content should not exceed 10%, while the water in the oil – water – based drilling fluid is a necessary component to disperse in the diesel oil, the water content is generally 10%~60%.

drilling
Advantages and disadvantages of oil based drilling fluid:
1. Compared with water-based drilling fluid, oil based drilling fluid has the advantages of high temperature resistance, anti salt calcium influx, be conducive to wellbore stability, good lubrication and less damage to the oil and gas reservoirs.
2. At present, it has become an important method for drilling high temperature deep well, high angle directional well, horizontal well and complex formation, and it can be widely used as a solution for the reservoir, the perforation completion fluid, the well fluid and the coring fluid.
3. Allocation cost of oil based drilling fluid is much higher than the water-based drilling fluid, and it will often cause serious influence to the ecological environment near the well site when using the oil based drilling fluid.
4. In order to improve the drilling speed, from the mid twentieth Century to the beginning of the 70’s, low gum oil emulsion drilling fluid has been used in a wide range.
5. To protect the environment and adapt to the needs of marine drilling, from the beginning of the 80’s, it is gradually promoted to use the low toxicity oil emulsion drilling fluid of which mineral oil is the base oil.

Abbreviated description of oil based drilling fluid

Oil based drilling fluid is the drilling fluid which use oil as a continuous phase. It is divided into whole oil based drilling fluid and oil water emulsion drilling fluid. Water is a useless component in the whole oil based drilling fluid, and its water content should not exceed 10%, while the water in the oil – water – based drilling fluid is a necessary component to disperse in the diesel oil, the water content is generally 10%~60%.

DC Solids Control

Advantages and disadvantages of oil based drilling fluid:

  1. Compared with water-based drilling fluid, oil based drilling fluid has the advantages of high temperature resistance, anti salt calcium influx, be conducive to wellbore stability, good lubrication and less damage to the oil and gas reservoirs.
  2. At present, it has become an important method for drilling high temperature deep well, high angle directional well, horizontal well and complex formation, and it can be widely used as a solution for the reservoir, the perforation completion fluid, the well fluid and the coring fluid.
  3. Allocation cost of oil based drilling fluid is much higher than the water-based drilling fluid, and it will often cause serious influence to the ecological environment near the well site when using the oil based drilling fluid.
  4. In order to improve the drilling speed, from the mid twentieth Century to the beginning of the 70’s, low gum oil emulsion drilling fluid has been used in a wide range.
  5. To protect the environment and adapt to the needs of marine drilling, from the beginning of the 80’s, it is gradually promoted to use the low toxicity oil emulsion drilling fluid of which mineral oil is the base oil.

Pollution of surrounding environment by well drilling fluid

Good performance of the drilling fluid is one of the basic conditions of the success of drilling, but the drilling fluid is easy to be polluted by H2S, gypsum, salt and CO2 and other pollutions then deteriorate and lose efficacy, which will impact on the safety of drilling seriously and increase construction costs. Therefore, we should pay attention to the environmental protection problems, let us understand the causes of the drilling fluid pollution and the way to deal with it following:

How do drilling fluid pollute environment

1. The organic compounds in the drilling fluid can not be easily degraded in the soil, they form a layer of isolation film, which prevent soil and plant from water absorption, in addition, some organic compounds are toxic, and is harmful to the water.

2. The oil and diesel oil in the drilling fluid also do great harmful to soil, plants and water.

3. The salt and exchangeable sodium in the drilling fluid can cause soil compaction, make the plant difficult to absorb water from the soil, which is not only go against the growth of plants, but also have a considerable impact on the groundwater.

4. Cuttings in the drilling fluid can produce more or less influence on soil, plant, groundwater and water.

drilling fluid

How to reduce or eliminate the pollution of the surrounding environment of well drilling fluid

1. Add little or none inorganic salt, especially sodium salt and the organic polymer that not easy to degrade.

2. Use the solid free drilling fluid as far as possible, one is easy to clean the debris, the two is not need to discharge and exchange the slurry, three is the drilling fluid can be reused.

3. Use high quality drilling fluid, so that the debris can whole deposit down in maximum possible in the circular groove, which will be easy to clean cuttings.

4. Qualified teams use the mud machine to reduce solid content and prolong the service cycle of drilling fluid.

5. Use the drilling fluid of upper well to drill soil surface.

6. Digging pit, mat plastic film, the cuttings will be filling up.

7 . Add curing agent to the finishing drilling fluid to prevent the drilling fluid from being harden, so that prevent environmental pollution.