Operator-requirements for cost effective technical solutions to borehole stability problems have historically been the impetus for new product and mud system development by the industry. Oil-based drilling fluids have long been recognized as a sound technical answer to problems encountered in deep-hot holes and, more recently, to stabilize boreholes with thick intervals of reactive clay formations. However, oil-based mud product development was slowing down until the introduction of low toxicity base oils in the late seventies created a need for new investigations. This innovation sparked a resurgence of oil mud research and development which has resulted in oil-based mud (OBM) systems being used routinely in many active drilling areas worldwide.
Concerns for conservation, both economic and environmental, persist even after low toxicity oils have been accepted, based on field performance, as a suitable diesel replacement. These concerns are important to both the operator and contractor alike. Control of intangible costs related to mud expenditures is important to the operator, but rig modification and installation of auxiliary equipment to process the oil-based drilling fluid are equally important to both companies.
This paper discusses a variety of equipment that is currently available for both onshore and offshore locations to improve oil-based drilling fluid conditioning, to aid oil recovery, to reduce pollution, and to maintain a safe working pollution, and to maintain a safe working environment. Minor modification of most of these techniques will allow their utilization on land, inland barge, platform, jack-up, semi or floating drilling units.
Field development of drilling fluid research efforts has always been oriented toward improving the financial and, more recently, environmental objectives of drilling mad production operations. New product and total system development combined with improved application of mud engineering technology will continue to have a positive impact on this cost containment effort well into the late eighties.
Future drilling activity in harsh environments will require improved drilling and logistics support equipment, better performance from consumables, and rigorous application of engineering principles to reduce the trouble time cost of each project. Selective application of oil-based muds has already contributed to this cost improvement on several recent projects in both the North Sea and the Gulf of projects in both the North Sea and the Gulf of Mexico.
Replacement of diesel with low toxicity oils as a babe in these mud systems has provided an unexpected benefit of increased rates of penetration with no appreciable increase in total mud cost. This benefit would be lost very quickly if efforts to reduce surface losses, to eliminate contamination to improve treating methods and to ensure a safe work site are not successful.
The following discussion will itemize various pi of equipment and techniques that can be utilized to handle these oil-based drilling fluids. Item selection for a specific application should be based upon the size and scope of that project.
Most drilling rigs require only slight modification of their rig floor equipment to be able to operate with oil-based muds WBML Mud buckets and pipe rack drains that can be directed back to the active system and textured (non-skid) metal surfaces around the rotary table are generally standard equipment on most land and offshore drilling units.
Potable water wash-down systems have replaced high Potable water wash-down systems have replaced high pressure washers and the steam hose system on some pressure washers and the steam hose system on some rigs operating with low toxicity oil muds (LTOM), even in cold weather environments. This is due to the improved surface tension characteristics of the base oil.