Pipeline Pigging Assessment

Project Background

The client operates a gas plant in a remote location in the Kurdistan Region of Iraq, producing Natural Gas (NG), Liquid Petroleum Gas (LPG) and Natural Gas Liquids (NGL). Sales gas is distributed to the local users (power plants) using the main pipeline of 24” diameter and 176 km length.

Penspen were contracted to assess and report on the piggability of the pipeline through a piggability study, liquid estimations and a scope of work for pigging operations, ensuring the resume of regular pigging for the client’s asset.

Services

The project’s scope involved overall assessments of the piggability of the sales gas pipeline, using pigging velocity and liquid estimations as inputs. This was achieved by:

• Defining the worst-case and most-likely operating scenarios for the estimation of liquid expected in the pipeline based on the pipeline operating history
• Carrying out steady-state simulations for a range of compositions, to estimate the amount of liquids produced during the pigging operation
• Determining suitable flowing conditions with Inline inspection, utilizing intelligent pigs with velocity restriction

Result

Through the pigging analysis and reporting, Penspen were able to offer the client:

• A comprehensive strategy for the most optimal time for pigging, alongside simulation results
• Recommendations for maximum pigging velocities, with a breakdown of sample flow rates and velocities for different seasons of asset’s life cycle
• A breakdown of the differences in upstream and downstream pressures for power plants and a further review of caution in respect to liquids and how the different pig methods could affect them

Additionally, Penspen provided alternative strategies which contained information for direct assessment methodologies and a scope of work for investigatory pigs and liquid handling equipment to ensure accurate pigging assessments.