In the operation of hydrocarbon liquid pipelines, Computational Pipeline Monitoring (CPM) systems are used for software based leak detection. When installed, CPM systems must meet the regulatory requirements such as API 1130 in the USA and CSA Z662 in Canada. API RP 1130 provides several methods that can be used to test a CPM system: forced parameter testing, simulated leak test (SLT), and fluid withdrawal testing (FWT).

Leak tests are performed to establish and verify the leak detection capabilities of the installed CPM system and in some cases test the response of the personnel. One of the primary interests in leak testing is the realism or hydraulic accuracy of the leak signature, in order that the reported leak sensitivity results of the test are reflective of the real performance of the CPM system.

Simulated leak tests (SLT’s) use an offline pipeline model to generate hydraulically accurate data which can be fed into the CPM model. SLT’s provide the most flexible and hydraulically accurate solution to simulating leaks, compared to some of the other API RP 1130 compliant test methods. SLT’s do not have leak location restrictions and also correctly models the flow and pressure hydraulic signature of a leak.

The paper outlines a novel approach and method to leak simulation, based on its size and shape of the leak hole. This method can be used to represent various sizes of a leak, ranging from a pin hole to a large rupture along the seam. Implementation of the method in a simulator developed with commercial software is discussed. The results of the simulation, namely the hydraulic signatures from the simulated leak and the CPM response, are compared with the widely used leak simulation method using a constant leak rate. Finally, possible applications of this method are considered.

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