Enhanced The Effectiveness Of Workover Program And Well Integrity By Combining Accoustic Ultrasound Leak Detection And Pressure Thermal Log In Depleted Mature Field South Sumatera - Indonesia

Abstrak

The evaluation of flow profile in the wellbore system is an important part of mature oil and gas field development. It is often complicated by life cycle of wells such as well design, completion strategy and production or injection phase. The high cost and tight economic margins require that the chosen well surveillance technique not only provides more effective workover program but also carries an acceptable risk in term of the project cost and safety. One of many well-known technologies is acoustic ultrasound leak detection and pressure thermal log. The objective of this paper is to show how a new approach of ultrasound leak detection surveillance technique combining pressure thermal log can be used to enhance the effectiveness of workover program in mature oil wells.

Accoustic ultrasound data acquisition is basicly passive acoustic measurement. Various sound waves generated by fluid movement in dynamic condition will be captured by accoustic sensor. It is separated into two different frequencies : a. Ultra low frequency or narrowband spectrum (8 to 4,000 Hz), b. Wideband spectrum (8 to 60,000 Hz). High resolution of pressure temperature data surveillance is also acquired to provide a comprehensive pressure temperature behaviour in the area of interest and surrounding formation.

As the result, This paper includes two case studies that demonstrate the integration of accoustic ultrasound and pressure temperature surveillance can identify undesired flow behind casing caused by well integrity problem that is not detectable with conventional method such as cement bond log and production logging tools. The first case is an artificial lift well that was challenging in data acquisition technique and operation. Another case is a gas well with high undesired water production. The data interpretation and comprehensive study provides unpredictable source of water production precisely. The source of water production was coming from non perforated zone through behind casing, squeezed zone and the casing liner.

This study should be a valuable analysis to guide the remediation plan. The well production performance can be restored through proper remediation job. Moreover, this paper should be beneficial to help all engineers currently working in brown oilfield not only to identify the source of production problem precisely but also develop a comprehensive and effective workover program.