Effects of soaking, stirring, and milling were investigated to standardize the washing method used for drill cutting samples. Drill cuttings are fragments of solid material ground by a drill bit at the bottom of a hole. They are recovered on the ship in riser drilling as a component of the circulating drilling mud. Removal of drilling mud from the surface of cutting samples must be done before cutting samples are analyzed. Cutting samples from IODP Expedition 337 were used in test experiments. The samples were analyzed before and after soaking, stirring, and milling with XRD, XRF, an elemental analyzer and a carbonate analyzer. Results show that Na and K contents are reduced by the removal of drilling mud. However, changes that occur after 6 h of soaking are rather minor. These results suggest that stirring of cuttings in heated seawater at 40°C for 6 h after quick washing is effective for XRF and TOC analyses. On the other hand, it was pointed out that the data from core samples and cuttings samples show differences; e.g., inorganic carbon content of cuttings was higher than those The sample preparation flow is presented in Fig. 1.A batch of 120 cc of cutting samples was quickly washed at once in seawater and was sieved with 0.25 mm mesh.The samples of >0.25 mm were sieved again in seawater for separation of 1-4 mm and >4 mm size fractions. The second sieving duration was 30 s. Iron grains, which were regarded as broken pieces of drill bit and drilling equipment, were removed using a hand magnet. Next, the sample batches were washed and sieved until the required volume of samples was obtained. To minimize variation in lithology, fragments of similar lithology were picked from the >4 mm size fraction. When the collected volume was insufficient, the 1-4 mm fraction was also used. In all, 160 cc of dark grayish- Table 2. Analysis of drilling mud sample 373-LMW (from Table T12, Expedition 337 Scientists, 2013a). From 385SMW, 40 cc of grayish brown to dark grayish brown silty shale, and another 40 cc of bluish gray to dark bluish gray sandstone were selected. Those were divided into four 10 cc samples respectively and were mixed to prepare four 20 cc samples: Samples C1-C4 in Table 1.Each sample set A-C was divided into four subsamples. Subsample 1 was vacuum-dried immediately without further washing. Subsample 2 was soaked in 200 cc of seawater for fixed periods; then they were vacuum dried. The soaking time was 6 h for sample series A, 24h for sample series B, and 3 h for sample series C. After Fig. 1. Four washing methods were used for this study: washing during sieving, soaking in seawater, soaking milled sample in seawater, and stirring in seawater. All samples were dried and milled for measurements. EA, elemental analyzer; CA, carbonate analyzer.JAMSTEC Rep. Res. Dev., Volume 22, March 2016, 39-48
41Experiments on method for washing drill cuttings: evaluation of soaking, stirring, and milling effects soaking, samples were filtered and vacuum-dried for 24 h.Then they were milled using a ball mill at 200 ...
