Intensive Evaluation of a Rig's Fluid Handling System Shown to Dramatically Improve Efficiency, Lower Costs

Abstract

A comprehensive and quantitative evaluation of the mud mixing, solids control and waste management systems on rigs prior to the commencement of a drilling operation has been shown to dramatically improve operational efficiency and ultimate fluid-related costs. This paper discusses the evaluation process, which includes an audit of the total fluids system, aimed at assuring that the solids control, fluids handling and mixing systems are functioning to specifications and configured properly for the well objectives. The authors will examine in detail the various components of an intensive rig evaluation, which include everything from the condition and configuration of the shakers to the dimension of the mud pits and their fittingness for treating and processing the specific mud volumes required for a given project. In addition, the evaluation includes a safety audit of all areas where fluid engineers will be working, such as the pit room and shaker house. In demonstrating the effectiveness of such an evaluation, the authors will consider specific examples, including audits conducted on newbuilds, rigs undergoing refurbishment and even to improve the solids control and waste management efficiency of units while a well was in progress. The authors will discuss the results of an evaluation of an entire fleet of deepwater rigs with emphasis on the subsequent recommendations. On one deepwater rig in the Gulf of Mexico, the operator saved $48,000 in fluid-related costs when the evaluation revealed that the solids control equipment was not operating at peak efficiencies. Many existing rigs are found to require only a minimum amount of repair or adjustments to show improvements. On most occasions, the evaluation can be used to construct more efficient solids processing and waste management plans. Introduction Be it a drilling rig or platform, an efficient fluids handling system produces a number of economic and operational advantages.1,2,3,4,5 If operating at peak efficiency and properly configured for the well objectives, the fluid processing arrangement, especially the solids control system, can increase penetration rates, reduce drilling fluid costs, minimize abrasion and wear and lower disposal costs. The environmental benefits of a proficient solids control system is illustrated by a reduction in the total volume of waste generated by the drilling operation. Critical to the effective performance of a total fluids handling network is having equipment that is properly sized, installed and operated as per the objectives of the well. For instance, just as the composition of drilling fluids employed in the deepwater environment differ significantly from those used onshore and in shallower water, the makeup of fluids handling systems likewise vary dramatically with specific well objectives. The application must be considered carefully when selecting and configuring the mud handling, solids control and waste management system. The equipment may be new and functioning superbly, but if not matched up correctly it is of little value. For example, the ability to circulate at high flow rates, thereby increasing penetration rates, can be restrained if the removal of cuttings from the drilling fluid cannot match the circulating rates.2 Furthermore, ever-tightening environmental regulations, especially those concerned with oil-on-cuttings retention, and the economic ramifications of using expensive synthetic-based and other expensive and exotic drilling fluids, mandate a handling system that will optimize fluid recovery. In addition, with total containment and cuttings slurrification becoming more popular, any existing fluid and cuttings handling system must be flexible enough to meet the requirements of those techniques.