Centrealoil-- Non-bentonite oil-based drilling fluid

With the development of oil and gas industry in China, more and more special operations were encountered,  for example ,large displacement horizontal wells, narrow window wells, shale gas wells, high temperature and high pressure wells and ultra deep wells, slim hole wells, ocean deep water wells and so on. Therefore, the technical requirements of drilling fluid is becoming more and more strict.Previous water-based drilling fluid has been difficult to meet the technical requirements to a certain extent. Oil-based drilling fluid has great advantages in many aspects compared with water-based drilling fluid, it reflects in four aspects:

①Cost: The cost of the initial single well is high, but because of oil-based drilling fluid can be repeated use, when used in large scale, the cost is lower than the water-based mud. This is also why the foreign mature oilfield development mostly using oil-based drilling fluid.

②Down hole security: The main reason of the downhole unsafe by using water-based drilling fluid is that lithologic substratum easily dispersed in water. But most of the lithology is not dispersed in oil, downhole safety. The down hole security has the safeguard.

③Lubricity: oil-based drilling fluid itself provides excellent lubrication performance, provide the conditions for large displacement well drilling.

④Performance and Maintenance: oil-based drilling fluid composition is simple, highly targeted, simple maintenance. Further provides guarantee for downhole safety.

But traditional oil-based drilling fluid has the following shortcomings:

①The use of organic soil materials as shearing potentiator has high solid content, is not conducive to improve the rate of penetration, static shear force is too large, easy to damage the reservoir

②The use of organic lignite materials as fluid loss agent reduce the rate of penetration, and has bad wettability with oil phase, increase plastic viscosity and thixotropy of the drilling fluid,limited high temperature resistance, is unfavorable to reservoir protection.

③Sensitive to water pollution and solid pollution.

④It has higher viscosity at low temperature (0-20 degrees Celsius), is not conducive to development of Marine deep water wells.

⑤The structural strength is too big, suction pressure is big, and easy cause downhole pressure instability.

⑥Go against the narrow window well development

⑦Treating agent dosage is large, complicated field maintenance

Aiming at the problems above, our company researchers developed non-bentonite oil-based drilling fluid system, has the following characteristics.

The technical characteristics of non-bentonite oil-based drilling fluid:

a.  Complex emulsifier instead of a variety of emulsifier:

①Below 150℃, use only an emulsifier;

②The density is lower than 1.8 SG can not use the wetting agent.

b.   Liquid synthetic polymer adhesive instead of organic soil as viscosity enhancer:

①Reduce the drilling fluid solid content, improve the rate of penetration;

②Take effect immediately after adding, don't need long shear;

③Dosage is less, only for organic soil content of 10-15%;

④Provide excellent suspension and hole cleaning ability.

c.  New synthetic fluid loss agent instead of organic lignite as fluid loss agent :

①To reduce drilling fluid solid content, and improve the rate of penetration;

②Oil soluble materials, reduce the wetting agent content;
③Improve drilling fluid rheological property;
④Low reservoir damage and can be used for reservoir drilling;
⑤The dosage is low, only about 15-30% of organic lignite.

                                          Centrealoil