Category Archives: Drilling Mud Cleaning System

07Sep 2012

Commonly used terms of drilling fluid

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1 Solid phase total

Solid phase refers to the solventless solid in drilling fluid. Usually the solventless solid in drilling fluid use percent by volume to express. The high density drilling fluid solid phase content consist of low density solid phase and high density solid phase, but the common drilling fluid solid phase content is all the low density solid phase.

2 Liquid phase

In drilling fluid, use liquid as dispersion solid phase continuity, it is called liquid phase. Usually, water, oil, soluble salt, thinner and other produce included.

3 Low density solid phase

The low density solid phase is including commercial clay and drilling cuttings. Usually, in the solid control work, assume that the density is 2.6/cm3 or 2.65g/cm3, the actual value in the 2.0-3.0cm3 fluctuation.

4 High density solid phase

The high density solid phase improves the density of the drilling fluid, make the annulus fluid column pressure is greater than the formation pressure. The barites is a kind of high density solid phase, the barites density is recommended by American petroleum institute is bigger than 4.2/cm3.

5 Aggravate drilling fluid

The commonly known as aggravate mud, the common aggravate materials is barites, according to requirements also can use other aggravate materials, in order to keep the minimum density.

6 Drilling cuttings

Drilling cutting belongs to solid phase, it is the main pollution source of drilling fluid. It is greatly affected the performance of drilling fluid, so must make the content is stably, so have the important issues, in the process of drilling should do regular treatment to keep the content is stably of drilling cuttings.

7 The clay

The clay is mainly made of clay minerals, the form is the super fine particles, most diameters is less than 2um, it has dispersibility in water, charged sexual, ion exchange, these performance is important to drilling fluid.

8 Colloid particles

The clay diameter of solid particles is less than 2um is called particles, the material of clay particles have a big surface area. Sodium montmorillonite can shape clay suspension in water, the dispersibility of the sodium montmorillonite is good, it can improve the viscosity of drilling fluid.

9 Oil base and water base drilling fluid

The oil base drilling fluid base on oil as continuous phase, the insoluble solid phase particles is scattered to the continuity liquid phase; Water base drilling fluid base on water as continuous phase.

10 saturated brine

saturated brine is allocated by sodium chloride, the density is 1.20/cm3

 

 

05Sep 2012

The process of mud purification

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Solid control system is mainly made of a group of store drilling fluid solid control tank and a group of equipment which rid of the solid phase in drilling fluid, solid control tanks which store drilling fluid are divided into circulating tanks and store tanks. Circulating tanks as a part of the ground cycle, there are shale shaker, vacuum degasser, deserter, desande and centrifugal on the surface of tank. The store tank is according to the need of drilling condition to allocated the different performance drilling fluid, or store drilling fluid which used for different drilling condition.

The purification process

1 level1 purification

The mud disposed in shale shaker. The allocation drilling fluid enter into the bottom well under the foundation of the drilling pump and carry drilling cuttings return the ground, through the elevated tubes enter into the shale shaker, the larger rock debris in drilling fluid are screened

2 level 2purification

When drilling fluid have gas cutting, we can use vacuum degasser remove the gas which in the drilling fluid and can recovery the density of drilling fluid, steady the drilling fluid viscosity.

3 level 3purification

The drilling fluid is disposed by the 2level purification enter into the desander through the desander feed liquid pump, the harmful sold phase which the diameter is above 40-60um is separated in desander.

4 level 4purification

The drilling fluid is disposed by the 3level purification enter into the desilter through the desilter feed liquid pump, the harmful sold phase which the diameter is above 15-40um is separated in desilter.

5level 5purification

The drilling is disposed by the 4level purification enter into the centrifugal through the centrifugal feed liquid pump, the small harmful sold phase particles are separated in centrifugal.

Usually, the 5purification is working at the same time. If it works one equipment or several equipments, the parameters of the drilling fluid can meet the work requirements, it can work one equipment or several equipments. After the purification, drilling fluid can enter into the next common drilling cycle.

28Aug 2012

How do we processing the gas invasion?

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When drilling the air layer, because the rocks are destroyed, the gap of the rock have a large of gas to immersion the drilling fluid reach the big crack or cave gas reservoir. It is maybe appear the large of gas of replacement immerse the drilling fluid.

1 Characteristics

(1)The density of the different of depth of the gas invasion is different .

(2)The density of the gas invasion drilling fluid will be very small when it is close to the ground, even if the drilling fluid gas invasion of the ground is very serious, the density is reduced, but the decrease of the pressure of the drilling fluid column is not very big, this time we can’t use the density of the ground gas invasion multiplied by the depth of the well to calculation the liquid column pressure.

(3)Because of long time to stop cycle (change the rig head, maintain the pump or electrical logging and so on), there is a large of gas column which is formed by nature gas under the well, when it rise to expansion, maybe led to the drilling fluid overflow.\

(4)After the drilling fluid gas invasion and closed, because the density difference, the nature gas will slip up, finally accumulate on the well month.

(5)In the case of the gas rise but it is not expansion , the pressure of the ground unequal to the pressure of the well month plus to the pressure of drilling fluid column, so we can’t use this pressure to calculate the required drilling fluid density.

2The damage of the gas invasion

(1)Reduce the density of the drilling fluid, after the drilling fluid density reduced, if the liquid column pressure is inferior to the ground pressure, it is maybe led to the well kick or blowout

(2)Make the absorption of the desander pump, priming pump and the drilling pump is bad, even can’t work normally, cause the device vibrate.

(3)Part of the toxic gas overflow from the drilling fluid, the operating personnel maybe poisoning.

(4)It can lead to fire.

(5)After the gas invasion, drilling fluid density will be increased, make the mechanical drilling rate decreased.

So how do we processing the gas invasion ?

The common methods of disposed the gas invasion

1 Circulation drilling fluid degassing method

It use the mechanical equipment continuously circulation drilling fluid on the ground, make the bubbles emersion the liquid level and overflow, the method only rid of the bid bubbles. The bubbles of diameter of less than 1mm, especially the bubbles of high viscosity, the foundation of cycle degassing is small. When use the methods to degassing, in order to reach the degassing effect, required long times, the drilling industrial is not allowed.

2 Chemical degassing method

Adding chemical gas degassing to the drilling fluid gas invasion, the method adopt to rid of the own bubbles. Use the chemical degassing method, need to mix and the time of reaction, so need long time, the high cost. The foundation is small to the gas of external invasion.

3mechanical degassing metood

Using all kinds of mechanical equipment, according the degasser clear the gas which immersing the drilling fluid. The methods apply to all kinds of the drilling fluid degassing. The mechanical degassing divided into ordinary pressure, vacuum type and the centrifugal.