Resolving the Problem of Atmospheric Statics Interference on Seismic Data during Seismic Recording Operation in Niger Delta, NigeriaJournal: International Journal of Scientific Engineering and Research (IJSER) (Vol.4, No. 2)
Publication Date: 2016-02-05
Authors : Madu Anthony Joseph Chinenyeze;
Page : 39-47
Keywords : Atmospheric statics; interference; seismic data; chargeable downtime;
The problem of atmospheric statics interference on seismic data during recording operation has remained a challenge that the cost implication on contemporary Seismic exploration budget in Nigeria, staggers up and down seeking for solution and subsequent harmony between the seismic contractors and their clients. Atmospheric statics interferes with seismic data when there is statics build up which tears apart to form separate positive and negative charges that travel in opposite directions as electric current, neutralizing the original accumulation of charges. The discharge superheats the surrounding air giving rise to ?bright flash?. The air in the discharge channel is heated to such a high temperature (T) that it emits light by incandescence. The clap of thunder results from the shock wave generated when the superheated air expands explosively. The discharged bright flash cuts into the seismic data, interrupting the data flow transported along Receiver Line telemetry cables or at line box LAUX at the time of ?bright-flash?. The release of the bright flash within the first 7 seconds after detonation of a shot or daily test shot, will strike the seismic data of that shot at a time within the 7 seconds record length of the shot. Rejection of shots affected by ?statics interference period? gives rise to delay or waiting or suspension of recording operation for some minutes sometimes ranging from 30 minutes to hour(s). It is tracked by the field Engineers by use of Skyscan statics tracking device, or checking on the pulsation until the statics cleared off the air to allow for normal recording operation without interference or line-breaks. Every hour of such a delay waiting for statics to clear in the atmosphere was regarded as ?Chargeable Downtime? due to statics at a contractual rate of about $10, 000 per Hour. Atmospheric statics discharge was a common cause of ?Line-breaks? as excess charge was neutralized by the flow of charges to the surroundings, which cuts across the seismic data on its linear-transfer to instrument truck. A seismic data from a shot can successfully be transferred to the Recording Instrument/Truck and saved to memory without statics interference, while data from the next shot may be caught up with statics interference causing line-break midway in the course of transfer, being pre-mature to full-record-length delivery to the Sercel Instrument memory storage. The Recording Instrument over the years has advanced in functions and capabilities. The France-based seismic recording Sercel Instrument has developed from one version to a higher version with time. Thus, Sercel SN 338 of 1971 gave birth to SN348 (1981-1986), to Sercel SN408UL (2000-2009), to Sercel 428XL (2007 - 2012). Each latest version has a higher level capabilities and sensitivity, and the atmospheric statics build up gives rise to interference strikes on the seismic data and line-breaks on one or more Receiver Lines, spoiling production recording. There tends to be a predominance of statics Interference on seismic data occurring in the ?Afternoons? of high air temperature changes (??), compared to the paucity of statics cases in the early morning hours.
Other Latest Articles
Last modified: 2021-07-08 15:34:14