As exploration and production operations move into deeper waters, producers are faced with new flow assurance challenges. One problem associated with deepwater production is the deposition of paraffin, asphaltene, hydrate, and scale within flowlines/pipelines. These depositions form partial pipeline blockages that reduce flow capacity and may ultimately put subsea flowlines at risk for complete plugging. Chemical inhibition, pigging, and other intervention techniques can be used to deal with this problem.; This dissertation presents a study of detection and location of partial blockages in flowlines/pipelines. New methods for estimating the sizes of partial blockages and locating them have been developed. This provides important information for monitoring the effectiveness of chemical inhibition programs, scheduling pigging, assessing risk for pigging, and planning other intervention procedures.; Recently, a steady-state analysis method based on backpressure analysis was developed to detect partial pipeline blockages using only routine production data or multirate test data. This study extends the backpressure method to subsea flowline/riser systems by considering elevation change.; While the steady-state backpressure method provides an indication of blockage size, location of the partial blockage was not possible. This study considers the application of the average pressure method as a new means of locating partial blockages in flowlines. When a blockage develops in a flowline, it changes the steady-state pressure profile and reduces the average pressure in the flowline. The average pressure is related to the blockage size (represented by a blockage factor) and blockage location, and can be determined through a simultaneous shut-in test (SSIT).; The pressure transient analysis is proposed as a general method for blockage location. For different blockage sizes and locations in a flowline, the transient pressure responses at the outlet (or inlet) are different. By a SSIT and the corresponding analysis model, this study developed type curves for blockage location/detection of gas flowlines.; The new partial blockage detection and location models were successfully used for analysis of available single-phase experimental data. In addition, the commercial software OLGA provided an important tool for verification of the proposed models. The OLGA simulation results demonstrated the correctness and validity of these models.
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