Black goop attack: special report on horizontal wells

Reducing the problems of declining performance as wells become plugged with deposits of materials such as asphaltenes and paraffins is the job of well maintenance, a segment of the oil field servicing industry that has seen relatively few advances in recent years. A new technique, ultrasonic irradiation, under development at Dalhousie University 's new petroleum engineering program, that promises to deal with this problem, is discussed, Coupled with in-situ foam treatment, the technique can be used to clean solid deposits from asphaltene-clogged sections of horizontal wellbores without expensive workovers. The process involves high frequency waves that break up the sandy tar into small particles which are then flushed out with surfactant. Currently being designed is a small ultrasonic device that can be inserted into producing wells via wireline. The device can be left in place and operated every four or five weeks as part of the regular well maintenance schedule. A prototype device is expected to be available later in the year 2000. Based on laboratory experiments, the device reduces plugging by reducing oil viscosity especially in the presence of asphaltic crudes, and through its ability to keep particles in suspension, probably through the generation of microbubbles. Another series of experiments by Droycon Bioconcepts Inc in Regina discovered various types of microbial debris within the paraffin and anthracene deposits, suggesting the potential for the formation of the deposits to involve microbial activity. This hypothesis is supported by the fact that the paraffin/anthracene deposit could be removed by the application of heat and the surfactant CB4