ENVIRONMENTALAND GEOPHYSICAL IMPLICATIONS OF DRILLING TECHNIQUESEMPLOYED IN ONSHORE SEISMIC DATA ACQUISITION

Abstract

Seismic survey which primarily involves using artificially generated seismic energy to examine the subsurface is a common exploration practice in Nigeria. The manner which seismic exploration is carried out affects not only the expected outcome but also the environment, the flora and fauna. In this study, implications of employing the following drilling techniques, the single deep hole technique and the pattern drilling technique were x-rayed as it affects the expected sampling of the subsurface and the human environment in line with the united nations sustainable development goals on sustainable environment and energy.To achieve this assessment, a 3D seismic acquisition design was employed within the study area, having a survey block consisting of 30 receiver lines oriented northeast to southwest, and 47 source lines running northwest to southeast. Safe shooting distances for acquisition were stipulated as a guide to preserve the environment and as well achieve the desired result. Linear acquisition was not consistently carried out due to some obstacles seen within the lines; hence, different types of point movement or offset were employed depending on the type of obstacle encountered. The following offset types - point shift, smooth curve and laminar flow were employed when obstacles were encountered on line. In this research, different drilling techniques, Single Deep Hole (SDH) and Pattern Drilling techniques were considered to ascertain the one with most desirable output, having the least negative impact on personnel, equipments, environment etc. SDH was adjudged to give a better result and with least or no environmental implications as compared to pattern drilling technique. Challenges of drilling operations which include drilling on wrong positions, drilling substandard depths, inaccurate measurement of hole spacing and stuck drilling stems were encountered minimally, and measures were taken to effect correction