Understand The Influence of Formation Stress on Verticality And Prevent Skew by Using Preformed Hole Technology

During the operation of rotary drilling RIGS, formation stress often "exerts force quietly", affecting the verticality of the borehole. And the pre-formed hole technology is an effective means to counter this kind of interference. Now I'll elaborate on the specific points for you.

1. Understanding the interference of formation stress: Uneven distribution of formation stress, such as in formations at the junction of soft and hard strata, when the drilling rig is under inconsistent force during drilling, can easily lead to the deviation of the drill bit and damage the verticality.

2. Principle of pre-drilled hole technology: Pre-drilled hole technology is similar to "taking the lead in advance". First, a small-diameter drill bit is used to drill a pilot hole to release formation stress and create a stable environment for subsequent normal drilling.

3. Select the parameters of the pilot hole properly: The diameter and depth of the pilot hole should be chosen based on the actual stratum. Generally, the diameter is 60% to 70% of the designed hole diameter, and the depth slightly exceeds the expected section prone to deviation.

4. Precise control of drilling direction: When drilling the pilot hole, rely on the high-precision guidance system of the drilling rig to monitor and fine-tune the direction in real time, setting a "benchmark" for subsequent drilling.

5. Arrange the drilling sequence reasonably: After completing the pilot hole, expand the hole layer by layer and stage by stage according to the design plan. The expansion amplitude of each layer should not be too large, and gradually reach the designed hole diameter.

6. Dynamic monitoring and adjustment: Throughout the entire pre-drilled hole and subsequent drilling process, the verticality of the borehole is continuously monitored. Any deviation is promptly adjusted to ensure that the deviation remains within the allowable range.

Conclusion: The influence of formation stress on the verticality of drilling by rotary drilling RIGS cannot be underestimated. The pre-hole-forming technology can effectively prevent skew through methods such as early stress release and precise guidance. Mastering these six key points can make drilling operations more precise and efficient, and smoothly advance the project construction.