Modernization of the API Recommended Practice on Rheology and Hydraulics: Creating Easy Access to Integrated Wellbore Fluids Engineering

Abstract

Abstract Tailoring drilling fluid hydraulics is one important key to the success of a drilling operation. Failure to do so can result in costly problems, negatively impact equipment longevity and performance, and ultimately jeopardize overall well objectives. In recent years the industry methods have deviated from API RP13D Standard Practice. This departure has been driven primarily by the increasingly onerous demands of critical wells, coupled with readily accessible computer power. In 2003 a Task Group was formed to modernize the existing API Recommended Practice Bulletin on Rheology and Hydraulics. It comprised a cross-functional team of operators, suppliers and academics which set an aggressive target to modernize the existing standard within two years. The focus was to develop simple, yet accurate methods, which could be readily implemented with basic spread-sheeting skills. This paper describes improvements made to the existing procedures and provides an illustration of how these methods can be applied to complex well designs. The paper also serves to introduce the industry to a modernized API Standard which offers an ideal foundation to inform new engineers of the fundamental concepts of hydraulic design and optimization. Introduction Rheology and hydraulics are central to successful well planning and execution of drilling operations, and there has been an API Recommended Practice (RP) in place since the mid 1980's. API RP13D1 has served the industry well as a guide to support these important issues. However it was widely recognised that the most recent version of this recommended practice required modernization. The primary drivers for this included:Increased well complexity beyond the scope of the current documentExtensive use of drilling fluids with physical properties sensitive to high pressure / high temperature (HP/HT) environmentsThe need to integrate wellbore engineering technologies to give a holistic approach. In addition a recently published paper2 concluded that the timing was right to effectively bridge the widening gap between field practices and the technology being introduced into advanced hydraulics software. By incorporating the basic fundamentals it is believed that the revised standard will serve both as a practical reference and a training guide. The intended target audience includes the office-based planning engineer and the wellsite operational staff (drilling engineer and drilling fluids engineer). A review of the existing RP13D identified the following areas as the primary focus for attention in enhancing the document: downhole behavior (rheology and density); pressure-loss modeling; hole cleaning; drilling optimization; swab-surge pressures; wellsite monitoring and rheological testing. A full listing of the revised sections is shown in Table 1. This paper introduces the modernized recommended practice which is currently undergoing final editing by the API. Also presented are revision improvements and their application to complex well designs, together with the project planning and management methods employed to complete the new document to meet an aggressive timeline.