| 摘要 |
<p>A pig delivery and transport system shown schematically in FIG. 1 has a looped line generally indicated at (10) divided into three sections (10A), (10B) and (10C). Line section (10A) is a low pressure non-product line section extending from a product receiving facility (PF) or host to an upstream shut-off valve (20). Line section (10B) is a high pressure product line section extending from downstream shut-off valve (22) to host facility (PF) and receives product from wells (W1) and (W2). Intermediate line section (10C) is a connecting line section between shut-off valves (20) and (22) to connect the non-product line section (10A) to the product line section (10B). A pig inserted at host (PF) is transported along low pressure non-product line section (10A) into connecting line section (10C) while upstream shut-off valve (20) is open and vent valve (28) is open in vent line 26. For transfer of the pig to the product line section (10B), shut-off valve (20) and vent valve 28 are closed and shut-off valve (22) is opened with a boost fluid obtained from a pressurized fluid source (32) through boost line (30) pushing the pig past branch lines (12) and (14) from wells (W1) and (W2). In this position, the pressurized product in product line section (10B) from wells (W1) and (W2) returns the pig to the product receiving facility (PF).</p> |
