A Case History Of The Scintrex Helicopterborne Pds3M Pipeline Detection System To Aid In The Safety And Planning Of 3D Seismic Surveys

Abstract

The Scintrex PDS-3M Pipeline Detection System was engineered to detect steel pipelines as small as 2 inches in diameter under favourable conditions. Using three Scintrex CS-2 cesium vapour magnetometer sensors arranged in a triangular fashion in a helicopter towed bird, the PDS-3 system measures all three components of the magnetic gradient and the total magnetic intensity. The data is interpreted to yield the location, likely layout of the magnetic responses. The combination of high sensitivity gradient measurements and data collection from an airborne platform allows for rapid surveying over areas which are difficult to access, such as over swamps. The PDS-3M survey yields a good infrastructure maps for the 3D seismic acquisition companies to plan their survey. The presented case history is taken from a PDS-3M survey over an oil field in Mexico. It shows that the existing infrastructure maps are often grossly simplified creating uncertainty in the “safe areas” for seismic shot point locations. With the increased confidence of the pipeline locations due to a PDS-3M survey, the safe areas for shotpoints were identified and gaps in the seismic coverage were tilled in. BACKGROUND There is an increased practice of shooting high resolution 3-D seismic surveys over mature and previously abandoned oil and gas fields. In many instances, the infrastructure in both abandoned and producing oil and gas fields is poorly documented and the locations are inaccurate. For safety reasons, seismic shot holes must be situated at least 100 metres from pipelines. Data quality and coverage also suffers if inaccurate knowledge of the pipeline network leads to an insufficient number of shot holes in a particular location. Therefore, the need to accurately locate pipelines and other cultural features is of paramount importance to the safety, planning and quality of 3D seismic data. In many of the areas that 3D seismic is shot, such as in swampy or watery locations, the traditional hazards survey often takes prohibitively long to conduct properly. The high operating costs of a 3D seismic crew means that any down time caused by waiting for a hazards survey to be finished is expensive. Due to the large area1 extent of oil and gas fields and the magnetic nature of the targets, airborne magnetic methods were an obvious, but challenging, choice. Scintrex’ PDS 3M Pipeline Detection was developed in conjunction with oil pipeline companies to have the ability, under favourable conditions, to detect pipelines as small as two inches in diameter.