The project goal is to develop a sonic well performance-enhancement technology that focuses on near-wellbore formations.

Program
This project was selected in response to DOE's Oil Exploration and Production solicitation DE-PS26-01NT41048, focus area Effective Environmental Protection.

Pennsylvania State University
University Park, PA

The overall strategy is to develop, evaluate, and characterize an acoustic excitation technique that can be used to stimulate oil wells by effecting flow improvement in the near-wellbore region. To this end, the investigators have identified the following tasks:

• Design and performance of a suite of laboratory-scale experiments that will examine and quantify the mechanisms associated with the cleanup of the wellbore and near-wellbore regions.,
• Development of a model that will incorporate the mechanisms identified in the laboratory-scale experiments into a model that can be used to scale up for field applications.
• Continued development of variable-frequency acoustic transducers that are designed to be integrated with the production string for continuous service in the wellbore environment.
• Field testing of the transducer in existing oil wells that will determine the effectiveness of the technology in enhancing productivity.

The following are the salient scientific and technical bases for the proposed work:

• The slim tube experiments are designed to help delineate the principal mechanisms governing the interaction of sonic energy and the wellbore environment that cause stimulation
• With a good understanding of the physics, a fundamental model with descriptive and predictive capability will be developed for the process. This model will be used for designing and implementing the sonic oil well stimulation technology in the field environment.
• The design and deployment of variable frequency transducers will help to delineate and apply the appropriate frequency and energy levels for formation penetration.
• Field implementation will help to enhance optimal configuration of the device for effectiveness and efficiency.
• The planned configuration will be such as to integrate seamlessly and easily with the existing production string without a need for significant modification. This will ensure reasonable deployment cost of the technology.
• Successful application of this technology will provide an effective, cheaper, and environmentally benign alternative to conventional oil well stimulation technologies.

Project Results
The successful development and deployment of sonic well stimulation technology will significantly enhance well deliverability and solve one of the perennial problems of oil and gas productivity, namely the impact of skin damage on oil well productivity. The principal focus of the proposed work is the development of this technology. The scope of the project is designed to cover laboratory experiments, mathematical modeling, transducer design and testing, and field-scale testing regimes. The successful completion of these tasks will produce a good understanding of the performance capability of sonication as a means to stimulate and remediate damaged wellbore zones, the mechanisms governing such processes, and the possible configuration for field deployment.

Benefits
The successful completion of this project and the deployment of the resulting sonic oil well stimulation technology (OWST) would provide the operator with a cost-effective and environmentally benign alternative to conventional well stimulation technology. The sonic technology will help independent oil and gas operators achieve breakthrough technology needed to extend the life of their wells and thereby increase ultimate production. This eventually could add significant reserves to the Nation's energy resources.

Project Summary
The slim tube experimental apparatus was designed, built, and tested. Using the slim tube set-up, one-dimensional flow data under the influence of acoustic stimulation were collected for a range of flow and acoustic parameters as well as various porous media characteristics.

A one-dimensional acoustic stimulation model was developed and tested. Specialization was done to isolate different phenomena, including cavitation and thermal effects. Due to limited time, researchers did not investigate the effects of interfacial phenomena. Students are in the process of extending this model to include some of these phenomena.

An attempt was made to develop the source function arising from cavitation, which turns out to play a significant role, at least under laboratory conditions. The next step is to incorporate this source term in a reservoir model that could shed light on the impact of acoustic stimulation of near-wellbore flow.

Field testing commenced with the drilling of four new wells, designed specifically for the testing of this sonic tool. In addition, one existing well was recompleted to accommodate the testing regime planned for this work. Log data as well as core data were acquired in order to form the baseline for the field deployment and testing of the tool. Appropriate metering and associated instrumentation were acquired in preparation for the field testing of the tool. This task has now been halted for lack of budgetary support.

(August 2005)
The project is in the third year of four-year funding.

$3,000,000

$752,924 (20% of total)

NETL - Jesse Garcia (jesse.garcia@netl.doe.gov or 918-699-2036)
Penn State - Michael Adewumi (michael@pnge.psu.edu or 814-863-2816)