Implications of Fold Monitoring in Seismic Data Acquisition: Case Study of Niger Delta

Abstract

Fold calculation and monitoring are an integral and important aspect of seismic data acquisition. Before an acquisition is carried out, so many factors must be put into consideration. These factors include grid orientation, source point (SP) and receiver point (RP) spacing, source line (SL) and receiver line (RL) spacing, source points (SP) number in each Salvo, receiver lines (RL) number in each swath, end taper, number of swaths, receiver line overlap between swaths and acquisition polygon limits. In this work, the study area was divided into 7 swaths of 12 receiver lines each, with the fold of each swath calculated in three phases which include near offset fold coverage (0 – 3650m), mid offset fold coverage (3650 – 7300m) and far offset fold coverage (7300 – 10950m). These phases of fold calculations were later merged to ascertain the full fold coverage of each swath and in turn the full fold coverage of the entire study area. The maximum fold coverage for each of the swaths within the study area ranges from 358 – 446, with average maximum fold coverage of 393.3 which is more than twice the minimum fold coverage expectancy (180) for the study area. Fold calculations were carried out, while the lateral extent where full fold coverage is experienced within each swath was noted. It was also observed that where the full fold coverage of one swath ends, the full fold of another swath begins. This implies that when all the swaths are merged, no fold drop will be experienced, unless at the tapering ends of the entire study area.