Abstract
Drilling operations require use of drilling fluid and solids control equipment to remove cuttings from the well. To maintain the drilling fluid at its desired properties it is essential to have efficient solids removal, which requires good solids control equipment in addition to good routines and practice for inspection of the shale shakers. Solids removal takes place in the shaker room, where the return fluid from the well is processed by shale shakers. Chemical emission of volatile compounds occur as the warm drilling fluid passes through the screens in the shaker and cuttings are discharged, and despite the use of ventilation system the emissions highly effect the working environment and point out the shaker room as a hot spot for occupational exposure.
During an onshore test of various shakers, factors expected to effect the chemical working environment while using oil based drilling fluid was examined. The factors were traditional open versus enclosed shaker design / front hood, and high and low ventilation rate. The evaporation level was monitored with a real time instrument for measurement of volatile organic compounds, while the level of oil vapour and oil mist were captured with filter and adsorbent tube sampling. The test methodology has been evolved from prior offshore and onshore tests (Bråtveit et al. 2009; Peikli et al. 2010; Steinsvåg et al. 2011; Aase et al. 2012).
The results from the chemical emission measurements showed that the separation system with highest degree of enclosure, i.e. fully enclosed, gave the lowest values, thus, provided the best chemical working environment. For semi-enclosed solutions, it was possible to reduce the emissions through optimizing the ventilation rate. However, the chemical emissions were still above the tests acceptance criteria. For a fully open system it was not possible to apply ventilation only in order to control chemical emissions to an acceptable level. As a result of the test all participating shaker suppliers have initiated design improvements to achieve a better chemical working environment in the shaker room.
