Test Research of Online Identification of Cuttings Lithology by LIBS Technology

With the development and application of new drilling technologies, the drilling time efficiency has effectively improved while producing increasingly small particle sizes of cuttings, which presents challenges to conventional mud logging technologies. In recent years, laser induced breakdown spectroscopy (LIBS) has achieved good application effect in cuttings lithology identification technology, but this technology still needs the manual collection and flushing of cuttings samples, and it faces the problems such as hard to collect the representative cutting samples for the encountered formation. Further, there have been challenges in resolving the difference between the identification results of cuttings lithology and the actual lithology of encountered formation. In order to solve the problems, the idea of using LIBS to identify cuttings lithology was proposed, and an indoor test platform was built, so as to explore the influence of laser source power on LIBS message. Through optimizing the laser source power, the acquisition accuracy of LIBS information was improved, and conducted LIBS measurement for the dry/wet cuttings samples and loose/compacted cuttings samples, respectively. The test found that the LIBS characteristics of cutting samples were stable under different states, and were in essence irrelevant to their states. The test results showed that the cuttings samples could be directly detected without any pre-treatment in the course of mud logging. Therefore, it is feasible to apply LIBS technology to realize the on-line identification of cutting lithology.