Innovative Application of Radio Detection System for
Detection of Crude Oil Theft from Cross-country Pipeline

The CAT Survey was employed for the first time to detect a point of pilferage other than its usual application of coating integrity survey techniques, emphasises Md. Sohrab Ali.

 

Introduction
Oil India Limited has a cross-country pipeline spanning over a length of 1157 km and traversing through all sorts of soil in three states of Assam, West Bengal and Bihar. It is almost a common phenomenon to have crude oil pilferage from the pipeline. Once it is sensed, there is no way but to detect it. In July 2001, drop of pumping pressure was observed in the Central Control Room through a particular period of time in the night and after certain time it came back to normal. It occurred due to pilferage by the miscreants at a very controlled rate as the pressure used to drop by about 2 Kg/cm2. This occurred mostly from 1 a.m. to 5 a.m. In view of above, it was decided to conduct Current Attenuation Test Survey (CAT) and undertake Pipeline Location Survey as an attempt to locate any foreign pipe leading out of the ROW. This is essentially, illuminating the pipe by injecting current and detecting the same through a capable receiver.

Aim
To detect foreign pipe connected to the main pipeline
i) Current Attenuation Test Survey (CAT).
ii) Pipe Location Survey on both edges of the ROW.
Equipment used
i) Radio Detection Receiver Unit – RD 432 PDL – 2 Nos.
ii) Transmitter Unit - RD 433 HCXT – 2AT 512 Hz mode – 1 No.
Basic Theory of CAT Survey
CAT Survey is very useful in identifying segments of poor coating. These high loss segments could either have holidays or are of poor insulating properties. In either case, the coating needs to be repaired. However, while conducting CAT surveys, there are numerous pit falls, about which the operator and analyst have to be well experienced to be able to analyse the data accurately. CAT Survey was conducted to detect the location, knowing fully well that the thief must have left the pipeline at a place of pilferage an electrical short circuit, cathodically speaking. If the pipeline is electrically consistent along the length, then rate of current attenuation will be uniform. Sudden change of rate of attenuation indicates change of electrical properties of the coating. Hence, it indicates coating fault. This technique injects a high power frequency of 512 Hz on to the P/L, through the Test Lead Points (TLP), using a high-power A.C. Transmitter. Using a hand held microprocessor based twin coil receiver placed over ground, exactly over the pipe, the signals strength flowing in the pipe at any two points can be measured. From the rate of decline ...

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