Planning Technique-Key to Drilling Efficiency (includes associated papers 14971 and 15044 )
Authors: Remson D. 
Published: December 2007

Drilling efficiency is a function of three variables:technology, equipment, and performance. Drillingcontractors can improve the performance of their rigs by applyingsound management principles to repetitive tasks. A wellcan be drilled on paper, so to speak, before it is drilled in practice. This type of planning helps to positioneveryone involved on the learning curve and permits problems and potential bottlenecks to be identified in time to take alternative action. Mutual expectations are developed between the operator and drilling contractor; therefore, thecompany man and the toolpusher have a common wellplan and schedule that define these expectations. Their performance is measured so that deviations from expected performance can be identified on a real-time basis and dealt with effectively. On the basis of contemporary tests. we anticipate abouta 10% reduction in time required to drill a given well, if the program described in this paper is fully implemented.

Introduction

Before drilling a well, the drilling contractor receives awell prognosis from the operator. This prognosis, or plan, outlines the various parameters under which the well willbe drilled, But even if the plan uses the latest drilling technology and if the contractor selected has the latest equipment, its ultimate success depends on the rig crew's ability to perform the drilling tasks in sequence. This paper describes a program in which the operator's well prognosis is reviewed thoroughly andsystematically. The analyses undertaken are not academic, but are entirely benefit-related. Time- and pressure-related aspectsof the plan are identified and quantified. The drilling schedule and related functions, such as rig maintenance and logistics, are separated into component parts, and planned, scheduled, and executed according to apredetermined, timed sequence. Benefits include these items:time savings,increased safety,increased control over wellprogress,creation of a data base for performancemeasurement and problem solving,application ofteaming-curve technology, andenhanced crew moraleand proficiency through goal setting and recognition.

Program Drilling efficiency is a function of three variables:technology, equipment, and performance.

DE=P(T+E).............................................(1)

where

DE = drilling efficiency, T = technology, E = equipment, andP = performance.

The proposed five-step program considers thecontribution of "performance"to drilling efficiency. A basic premise provides that success depends on the rig crew'sability to understand the drilling plan. They must know and understand the duties and obligations of everyone involved and carry out the plan according to mutual expectations.

Step 1. Review the operator's well prognosis and quantify pressure-and time-related aspects.The pressure profile is reviewed, and additional dataare gathered if requested by the operator. Also, someonemay add information because he has had previous experience in the area. The pressure profile is studied toidentify the existence and location of transition zones, toselect casing seats, and to define the difference between required wellbore pressure at any depth and the fracturepressure at the last casing seat. This information is veryimportant in circumstances in which a narrow band ofwellbore pressure is critical. Fig. I is a sample pressure profile.The depth-vs. -time curve (historical rig time curve)is the operator's statement of acceptable rig performance. It must be studied in detail. In addition to time expectations, the information it contains, such as hole sizes, casing sizes, setting depths, mud weights, logging intervals, etc., is the basis for the contractor's planning and scheduling.The remainder of the forecast is reviewed toprovide familiarity with special requirements and features ofthe well. Operators differ as to how much information they furnish. Ideally, the prognosis contains sufficient information on the directional program, cementing program, possible problem areas, service companies to use, mudand bit records of previous wells, and other useful proprietary information.

By taking these review steps, the contractor becomesfamiliar with the well program and ascertains theoperator's expectations and the contractor's corresponding obligations. A degree of proficiency in understanding well plans isrequired to review the drilling prognosis adequately. Inthis regard, the program is prefaced by a training seminar for contractor rig management and supervisory personnel.

JPT

P. 1613^