An interesting history of the development of mud cleaners

The first mud cleaner was a combination of two 12-in and 20 40-in hydrocyclones installed on a specially manufactured 5 ft diameter double-plate circular stainless steel drilling fluid shaker. Although the mud cleaner was invented to handle heavy drilling fluids, it was first applied in 1971 on a well that processed potassium chloride non-heavy drilling fluids. The well was 2200 ft deep and was located on a shoal near Houston, Texas. An API80 screen was installed on the unbalanced elliptical linkbelt drilling fluid shaker to process fluid from the wellbore, which was then pumped into the cyclone of the mud cleaner. This well was initially used to evaluate the effect of injecting air into the riser to reduce the annulus pressure near the seafloor, and was later used for exploration wells.

Mud cleaner

Mud cleaner

The second mud cleaner is a group of 20 4in "pioneer" brand hydrocyclones, which are installed on another specially manufactured 4ft diameter double plate circular stainless steel drilling fluid shaker. These screens can be installed in parallel or in series to handle the underflow treated by the cyclone. The mud cleaner was installed on a development well in southern Louisiana. Gas-bearing formations have a pore pressure of 11.0 lb / gal at a depth of 11,000 ft. The gas-containing depth is 11300 ~ 16000ft, and the depleted pore pressure is as low as 2.2ppg. It is planned to use the 11.0 lb / gal water-based drilling fluid to drill through the upper section, then run the casing and drill through the development section. As you pass through the upper well section, the pressure difference between the wellbore fluid and formation pressure increases to 6000 psi. A drilling fluid centrifuge is used with a mud cleaner to dilute the drilling fluid to maintain a very low concentration of cuttings to form a compressible mud cake. There were no leaks or stuck during drilling. Drill string torque and drag are minimal. After drilling to a depth of 80 ft from the casing, the mud cleaner was turned off (in fact, company personnel advised researchers to go home for Christmas because they didn't really need new experimental equipment because they had no problems). When drilling the last 80 ft, the drill string friction and torque are quite large, the casing is actually not deep, 120 ft lower than the expected depth, the concentration of drill cuttings in the drilling fluid has increased sharply, and each well needs to pass through before logging. Because too much drill rod torque and friction were generated, the research team was asked to return to the site and reopen the mud cleaner. A large number of particles appeared on the screen of the mud cleaner after being abandoned by the desilter. The API200 screen cannot handle all the fluid. The API150 screen is installed on the mud cleaner to reduce the drill cuttings generated in two cycles. Then, use API200 mesh screen for two weeks for final cleaning. The cuttings concentration is higher than the previous cuttings concentration, but sufficient to remove enough cuttings to allow the casing to smoothly descend to the predetermined position and cement the well.
Please note that this lucky event of shutting down the mud cleaner was the reason for the commercialization of drilling fluid mud cleaners. There are no plans to drill stuck. No one is studying here. The research plan should include a process to verify the performance of the mud cleaner. Because no problems were anticipated (although stuck and cyclic losses are common in wells with a differential pressure of 6000 psi), there is no comparable data to confirm that the mud cleaner is working well before the machine is fortunately shut down. This is also a huge lesson for your own process. The research team focused on keeping drilling fluids in good condition and minimizing the impact of cuttings. Unfortunately, not all drilling experts at the time believed that cuttings were harmful.
The drilling fluid centrifuge developed by Jk, heilhecker and LHrobinson of EXXon Production and Research Center was granted US Patent No. 3766997 on October 23, 1973, but this patent is invalid because there is one in the British invention patent A similar invention, and earlier than it was invented. A German inventor had developed a similar device in the late 18th century. Although his invention never became an application, it was not used in petroleum, and it was not widely used in actual production. The drilling fluid vibrating screen was also a coarse mesh at that time, but the existence of no copyright information indicates that the above invention does not require a usage fee (interestingly, all companies that provide mud cleaners are required to pay a US $ 5 daily fee as a technology transfer fee It is said that to help develop new products, service companies were told that after the request was rejected, after the patent was issued, they were required to pay more royalties. Due to the invalidity of the patent, all service companies never paid the so-called Royalties and technology transfer fees).
Less than a year after the original patent was issued, the mud cleaner was first commercially applied to two wells in the Pecan Island oil field in Louisiana, one of which was a production well and the other was a exploration well. Due to the first use of a mud cleaner in this area, coupled with the low concentration of cuttings in the drilling fluid, it is possible to move up and down the middle length casing during cementing operations. These wells have significantly less torque and friction than wells that previously did not use mud cleaners.
When mud cleaners appeared, many people considered whether to use a mud cleaner or a drilling fluid centrifuge. The reason is simple. The ability of a mud cleaner to remove solid phases is not comparable to a drilling fluid centrifuge. In heavy drilling fluids, mud cleaners are used to remove debris that is larger than barite (greater than 74 μm), while drilling fluid centrifuges are used to remove debris that is smaller than most barite (5 smaller than barite) ~ 7μm).