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A New Cementing System to Improve the Interlayer Isolation of Horizontal Wells (Part 2)
  1. 01. Result of acoustic well cementation quality measurement

The CBL measurement results of oil wells using ICSare encouraging, and the cementing quality is greatly improved. In the first five well experiments, ICSwas added to the tail mud. In one well, the additive was only applied in the horizontal section, and ICSwas added in the other four wells and the whole cement section. The cement roof of all the wells is designed according to the industry standard, 500 feet above the pipe shoe.


By comparing the CBL well logs of five test wells with the datum maps, the beneficial effect of ICSis immediately shown. In laboratory tests, the forces required to displace high yield materials were measured. Therefore, CBL logging results can be interpreted more confidently to provide isolation for additives than to improve CBL response. These results will be discussed in the full text.

  1. 02. ICS  concept

ICSis a stimulus responsive cement platform with simple design rules. For wells drilled with oil-based mud, poor interlayer isolation can be avoided in cementing. ICS

 contains polymer material which is dry mixed with cement before pumping. When the cement is replaced in place, the interaction between ICSand residual oil-based mud will cause obvious rheological changes, which will increase the yield value of oil-based mud in the channeling by 20 times. Maintain a pressure difference of 1000 psi every 10 feet according to the shape of the channeling. This rheological change occurs before the cement slurry reaches the ultimate compressive strength, so that the oil-based slurry channeling can withstand high pressure difference. This additive can be added to the existing slurry without any significant change in the initial target performance of the slurry and can be pumped without reducing the displacement.


In the process of increasing production, ICSis applied to improve the maximum pressure of cement sheath and channeling after reconstruction, which proves that channeling after reconstruction can bear the pressure difference between different fracture sections. This enhanced hydraulic isolation will help to avoid fractures only in the direction of low ground stress, reduce the curvature and fracture initiation pressure, and avoid the connection between well sections.


Considering the challenges of horizontal cementing, ICSis a good mitigation measure for the remaining mud. However, it cannot be regarded as a substitute for mud removal. Therefore, even if the technology is applied, the basic mud removal best process should be followed.

03. Conclusion

With the use of more field tests and other evaluation methods, including ultrasonic imaging tools, early results show that the cement system has a positive impact on cementing quality. Combined with the laboratory test, it is confirmed that the new ICScan change the oil-based mud in the channeling channel, and it is possible to improve the hydraulic sealing ability of the oil well. The effect is far better than that achieved only by removing the mud.