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MULTIBUR - accident free way to Devonian oil
27.08.2012

In August 2012 during well construction No. 19452G of Pavlovskoe field Republic Tatarstan drilling of interval 1,791-1,958 m was conducted with flushing using water based gel-emulsive mud MULTIBUR. This interval represented directional section with inclination angle 75-78 degrees composed mainly of problem argillites of Kuynovsk clays.

During horizontal well construction through Kuynovsk clays, usually, it can be seen the range of problems connected with troubles of wellbore, sloughing, failures and caving as a result of which because of slant borehole dome collapse the ring channel is surpassed by formation inducing sticking and also it can lead to multiple redrilling.

This complicated engineering problem was successfully solved by using water based gel-emulsive mud MULTIBUR including passing the section of inclination angle increase and outcome to horizon and drilling horizontal wellbore.

The following moments were noted during drilling:

  • Mud is exceptionally stable (does not exfoliate and foam).
  • Provides wellbore walls stability.
  • Perfectly prevents clay dispersion.
  • Round trip operations are run without overpulls and landings.
  • Expenses decreased because of volume reduction of prepared mud.

Parameter

Actual value

Density, kg/m3

1,300

Relative viscosity, s

51

Plastic viscosity, cP

18

Yield point, lbs/100ft2

25

Gel strength, lbs/100ft2

8 / 15

Filtration rate, ml/30min

1.8

Colloidal phase content, kg/m3 (not more than)

17

Hydrocarbons content, %

10

pH

8.5


All operations were made in customary mode without overpulls and landings, average ROP was 9 m/h, 168 mm casing running and cementing ware made in normal mode.

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