Drilling Wastes Treatment and Management Practices for Reducing Impact on HSE: ENI/Agip Experiences

Abstract

Abstract A growing awareness and sensitivity of the environmental pressure on E&P industry activities has changed rapidly in world-wide. One of the major troublesome environment complications is the mud exhaust and cuttings disposal problem. This paper reveals the recent experiences of our Drilling Unit in approach to fluid wastes treatment and management exercises in drilling operations toward minimum impact on HSE. In particular, some innovative wastes treatment and re-using technology approaches are discussed together with case studies to affect how waste mud and cuttings are handled, treated, disposed, and reused. Apart from waste and cuttings treatment, management and disposal processes the presented paper illustrates also Agip policy, Italy regulatory limits on environment issues. The described new treatment processes can be carried out at well site for all types of operation fluids. After suitable treatment, the wastes can be turned out as useful materials favoring both in situ and for other producing industries. Good and properly treatment, management and disposal of drilling cuttings and exhaust mud can make oil & gas well drilling more compatible with natural environmental requirements. The reduction of environmental impact became a benefit due to less volume (40 %) of wastes generated, less transport (20-30%) used, less accident risks during the transportation witnessed, and zero or minimum wastes to disposal sites were brought. From different operation case histories of our unit, water (60 %) from dehydration of WBM and oil (10 %) recovered after clean up from oily cuttings are re-utilized for mud service company at rig site. The treated solids (cuttings and components of mud) are no longer wastes to be disposed but raw materials for 1) cement producing plants 2) bricks and expanded clay producing plants and 3) for land restoration. The experiences, obtained by Eni/Agip up to date provided the very encouraging results not only from cost saving point of view but also as a great contribution to improvement of environmental impact of our activities. The great contribution was derived from:reducing operation duration;less volume of wastes production;zero or minimum discharge drilling wastes;wastes materials as raw materials for re-use: treated liquid (water and oil) is reused for mud built up, dilution and rig cleaning; treated solids are reused as useful materials. Introduction Many E & P petroleum activity operations, such as emissions, discharges, unplanned accidents and duration of operating time, have adverse effects on health, safety and environments (HSE). Among these operations, managing drilling mud system and discharging wasted mud and produced cuttings are key source on HSE impacts. Agip has been carefully managing the environmental elements of its activity both in Italy and abroad since the 70's. Drilling activities were carried out mainly by using water-based mud (WBM) and exhaust fluid and cuttings were discharged at sea till the middle 80's. After the introduction of more tight environmental limitations and increasingly use of oil based mud (OBM) justified by technical needs, Agip took the voluntary guidelines that wastes (both exhausted WBM/OBM and cuttings) produced in Italian offshore operations are to be transported to onshore disposal sites - that mean zero discharge policy[1]. The wastes both transported from platforms and produced on onshore operation, have to undergo a series of treatment and consequently, must be disposed after satisfying the limits of the laws issued by the government.