Abstract

Conoco acquired two 3D seismic surveys over three small oil fields in South Natuna Sea Block B (SNSB) during 1991. These small oil fields might not have economically supported stand alone 3D seismic surveys without the cost savings realized by shooting them in tandem with the large Belida Field 3D seismic program. The subsequent processing and interpretation of these data have provided valuable information on reservoir geometry and faulting. In addition the 3D seismic data are now beginning to yield stratigraphic information that may provide predictive models of reservoir quality and quantity to further guide the development drilling plan. The results of these 3D surveys have influenced Conoco Indonesia's philosophy on the value of 3D seismic over small fields.

Cost differences between these small field 3D seismic surveys and conventional 2D appraisal infill seismic surveys are insignificant when the benefits of a more efficient appraisal and development program are considered. In many small fields, an extensive appraisal well program is unacceptable within the overall project economics. The 3D surveys allow more confidence in predicting reservoir performance with a limited appraisal well program. Development of small fields in SNSB is done with floating production facilities and sub sea completions. These floating production systems necessitate pre-drilling the production wells before the facilities are floated in and the flow lines are tied back. There is no second chance or "learning curve" from the production wells. The 3D survey increases the opportunity that these wells are optimally located for drainage and result in maximum net present value.