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A New Cementing System to Improve the Interlayer Isolation of Horizontal Wells (Part 1)

The new ICS can change the oil-based mud in the channeling channel and may improve the hydraulic sealing ability of the oil well, which is much better than that achieved only by removing the mud.

At present, most horizontal wells in the United States adopt multi-stage stimulation measures. In order to effectively increase production, it is necessary to isolate each well section inside and outside the production casing. In casing, although bridge plugs can be used between well sections to form effective isolation, cement must be able to form external isolation. Cementing operation in horizontal section is carried out according to the design, however, it is difficult to fully optimize all design parameters to achieve the best cementing operation. Moreover, few operators carry out cementing quality logging in horizontal section, and channeling in annulus is often considered as the root cause of low production increase efficiency. As well completion efficiency and well productivity depend on good interlayer isolation, it is generally believed that the profitability of oil wells has also been affected.

Mud removal is still an integral part of cementing operations. A new cement formula has been developed in the industry, which can improve the isolation effect between layers under the condition of poor mud removal. ICS can react with hydrocarbons in oil-based drilling fluid to reduce the permeability and fluidity of channeling, thus significantly improving the possibility of hydraulic isolation. In addition, a special test protocol has been developed to demonstrate the functions of the new system. In addition, the testing methods and analytical techniques of the American Petroleum Institute (API) were used to optimize the cement slurry.

For decades, the industry has been trying to improve cementing quality by optimizing the design standards discussed above, but a new idea needs to be changed. ICS was developed according to the idea of converting the residual oil-based drilling fluid into plugging material. This system has enhanced the interlayer isolation effect of residual well section of oil-based drilling fluid after cementing operation. The development of new cement system focuses on optimizing the concentration of active components to provide interaction with oil-based drilling fluid, while ensuring no impact on the rheological and mechanical properties of cement slurry. The internally developed program shows that the new system effectively reduces the hydraulic conductivity of micro annulus and 0.1 inch channeling.

Laboratory tests are designed to measure the ability of ICS to change oil-based drilling fluids. During conventional stimulation operations, this measurement can be used to estimate the pressure bearing capacity, and preliminary results show that the additive can completely isolate the external wellbore between different well sections. An oil and gas company in the Permian Basin agreed to test the new additive in five 10000 foot horizontal wells. The cement bond log (CBL) is used to identify the top of the cement and evaluate some sections of the cementing operation from the top to hundreds of feet above the kickoff point. Review the logging results to determine whether the conversion of oil-based drilling fluid can be measured. There is no doubt that fluid conversion does exist, and this result complements the laboratory tests.
The most exciting thing is that ICS can play a more important role in the wellbore drilled with oil-based drilling fluid. In addition to isolation of the fracturing section, there are many other reasons for wells to use isolation. For other possible applications, there are plans to conduct additional tests.