Test Analysis of a 2D Seismic Survey With Finer CMP Interval

Finer bin size or CMP interval normally means higher cost for a seismic survey, which makes sense for 3D projects because of very large equipment investment and difficulties of recording crew organization. However, the increase of active channels seems not to increase much cost for a conventional 2D seismic project in Indonesian jungle where the large portion of the cost is from line clearance, bridging, drilling and damage compensation. A test 2D line with 10 m receiver interval (RI), 60 m source interval (SI), 720 active channels and bunched geophone was acquired versus the production parameters of RI 30 m, SI 60 m, active channels 240 and arrayed geophone. The results demonstrate that flexible indoor arrays produce better effects than infield arrays where surface inconsistences exits. Data sets with RI of 20 m and 30 m with nominal full fold of 60 extracted respectively by picking one trace every two and one every three were processed. The comparisons of brute stacks with CMP interval 5 m, 10 m and 15 m demonstrate finer CMP interval can mitigate spatial aliasing and hence, improve denoising and S/N ratio. Instead of geophone array, the test data were also processed with nominal full folds of 120 and 180 by enlarging CMP intervals to be 10 m and 15 m. The comparisons indicate higher fold coverage can significantly improve seismic imaging with no negative impacts from geophone array. A trial with RI 10 m, CMP interval 15 m and SI 120 m was processed with nominal full fold 90. The purpose of such test is to seek a possible alternative of 2D geometry with dense receiver but sparse source for areas where the number of source holes is desired to be less. This paper intends to discuss ways for 2D seismic surveys cost-efficient and environmentally-friendly.