The importance of data accuracy cannot be overstated, especially in the oilfield where every second counts. It is important to know exactly what is happening down the hole and act quickly in case of emergencies. However, the importance of data accuracy goes far beyond just decision making as it improves productivity. A pioneering project in the middle east has utilized a new acoustic monitoring technology to improve data accuracy in open hole multi-stage frac operations.

An innovative acoustic monitoring system has been developed in order to have an additional layer of acoustic and pressure data to detect and confirm events in real time. This technology utilizes sounds and pressure data to verify what is happening downhole. The system is very compact and can typically be rigged up and ready to acquire data in less than two hours. Pressure transducers installed in the treatment line and the ball injector line collect and display data in real time. The system collects data at a very high rate as data shows pressure in 10,000 samples per second compared to the conventional pressure sensor which shows pressure in 3 samples per second.

The new acoustic monitoring system proved to be a success as it shows clear indications of balls launching from the surface, balls landing on the seat and shifting of sleeves. The trial test well included five stages, only three of which were stimulated. Each stage utilized a single-entry port and was flanked by two open hole packers, one on each side in 5.875in open hole. In the first stage, the acoustic monitoring system successfully showed the pressure drop and captured an acoustic signature during rupturing the disc of the hydraulic valve. In the second and third stages, the system showed clear acoustic signatures during ball launching, ball landing on seats and sleeves shifting. In addition, the system also captured clear pressure indications during shifting of sleeves. This data cleared any doubts that could have occurred during the frac operation in multi-stage fracturing and saved a lot of time that could have been wasted reaching a decision on whether sleeves have been shifted or not. The new acoustic monitoring system improved the overall efficiency of the operation by capturing all events and hence increases the confidence of the operator in the downhole tools.

The successful completion of these trial tests shows how critical having reliable data on a timely basis. It includes a number of multi-stage frac technologies with an additional layer of acoustic monitoring which allowed operator to see in real-time downhole operation changes within equipment. This new acoustic monitoring technology proves to be beneficial especially in cases where pressure signatures are not clear. Having reliable data that explains the situation downhole would improve the visibility and help decision makers to act or react quickly.

You can access this article if you purchase or spend a download.