Calibration is an often-overlooked aspect of hydraulic modeling, but the impact of ignoring this potentially crucial step can be immense. It is not uncommon for significant pressure losses to be incurred in relatively small facilities that can often be glossed over as mere minutia when constructing a model. This paper will provide insight into the challenges faced while calibrating Access Midstream's Barnett hydraulic model and some of the solutions that arose during that process.
There are a number of areas that can cause a model's hydraulic behavior to differ from that of the system it is attempting to represent. These areas include the following:
Measurement Data Integrity
Flow Loop Handling
Access Midstream is a publicly-traded Master Limited Partnership (MLP) that was spun off from Chesapeake Energy's midstream division in 2013. It has operations in 7 regions spread across 9 states with an average throughput of 3.8 billion cubic feet per day (bcf/d) and more than 6,700 miles of natural gas gathering pipelines.
Access's Barnett assets include approximately 860 miles of gathering pipeline with a throughput of over 1 bcf/d. The system includes 24 compression facilities using more than 154,000 horsepower. The Barnett hydraulic model includes 615 receipt points (including Chesapeake well pads and interconnects with third parties) and 59 delivery points. For calibration purposes, data from over 2,500 meter stations are used, with most stations providing flow, pressure, temperature, and composition data.