(i) Direct method

In the oilfield, the simplest form of manual sampling is performed by using a plastic bottle. The bottle is connected to a bleed valve which is mounted on the production line. Further, the bottle should be connected to a gas treatment system (flaring, venting) that takes care of any associated gas. A schematic of the system is shown in Fig. 17. By careful opening of the valve, the liquids are bled off from the production pipeline into the bottle. A mixture of oil and water is normally collected by this method (Fig. 18).

(ii) Well head sampling method

Another somewhat more sophisticated manual sampling method involves the use of a phase separator that is connected to the well head (Fig. 19). The sampling procedure is as follows:

• The separator equipment is connected to the well head.

• The valve at the well head is opened and a mixture of oil and water flows through the main pipeline. A bypass is led into the separator.

• The oil phase is located in the upper part of the separator and is from there continuously transported back to the main pipeline.

• The water phase accumulates in the bottom of the separator.

• Water samples can be collected continuously from this equipment by opening the valve at the bottom of the separator.