Petroleum Engineering 405 Drilling Engineering * Well Drilling Engineering Drilling Cost & Drilling Rate Dr DO QUANG KHANH * Contents The AFE Drilling Cost and Bit Change Factors Affecting Drilling Ra[.]
Well Drilling Engineering Drilling Cost & Drilling Rate Dr DO QUANG KHANH Contents The AFE Drilling Cost and Bit Change Factors Affecting Drilling Rate Bit Weight, Rotary Speed Bottom-hole Cleaning Mud Properties, Solids Content HW # ADE 1.12, 1.13, 1.14 Before getting approval to drill a well the Drilling Engineer must prepare an AFE - a detailed cost estimate for the well DRY HOLE COMPLETED INTANGIBLE COSTS $ $ TANGIBLE COSTS $ $ TOTAL COST $ $ AUTHORIZATION FOR EXPENDITURE (AFE) EXPENDITURE DRY HOLE COMPLETED (24.5 DAYS) (32.5 DAYS) INTANGIBLE COSTS LOCATION PREPARATION DRILLING RIG AND TOOLS DRILLING FLUIDS RENTAL EQUIPMENT CEMENTING SUPPORT SERVICES TRANSPORTATION SUPERVISION AND ADMIN SUB-TOTAL 30,000 298,185 113,543 77,896 49,535 152,285 70,200 23,282 814,928 65,000 366,613 116,976 133,785 54,369 275,648 83,400 30,791 1,126,581 TANGIBLE COSTS TUBULAR EQUIPMENT WELL HEAD EQUIPMENT COMPLETION EQUIPMENT SUB-TOTAL 406,101 16,864 422,965 846,529 156,201 15,717 1,018,447 1,237,893 1,423,577 2,145,028 2,466,782 SUB-TOTAL + CONTINGENCY (15% ??) Drilling Cost vs Time DEPTH ft TD DAYS or DOLLARS Drilling Cost Analysis The Drilling Engineer: Recommends drilling procedures that will safely drill and complete the well at the lowest cost possible Makes recommendations concerning routine rig operations: The Drilling Engineer Examples of routine rig operations drilling fluid treatment pump operation bit selection handling problems during the drilling process The Drilling Cost Equation: Cb Cr( tb tc tt ) Cf D Cf = drilling cost, $/ft Cb= cost of bit, $/bit $ ft Eq 1.16 D = footage drilled with bit, ft/bit Cr = fixed operating cost of rig, $/hr tb = total rotating time, hrs tc = total non-rotating time, hrs tt = total trip time (round trip), hrs Example 1.5 A recommended bit program is being prepared for a new well using bit performance records from nearby wells Drilling performance records for three bits are shown for a thick limestone formation at 9,000 ft Determine which bit gives the lowest drilling cost if the operating cost of the rig is $400/hr, the trip time is hours, and connection time is minute per connection Example 1.5 cont’d Assume that each of the bits was operated at near the minimum cost per foot attainable for that bit Bit Bit Cost ($) Rotating Time (hours) A B C 800 4,900 4,500 14.8 57.7 95.8 Connection Time (hours) 0.1 0.4 0.5 Mean Penetration Rate (ft/hr) 13.8 12.6 10.2 Which bit would you select? 10 Economic Procedure in above Table Can pull bit after about 25 hr ($42.50/ft) - the precise pulling time is not critical Note that the cost in dollars per foot was $43.00 after 30 hr Primarily applicable to tooth-type bits where wear rate is predictable 19 Economic Procedure in above Table Also used with tungsten carbide insert bits when inserts are broken or pulled out of the matrix Unfortunately, wear rate with insert bits is unpredictable Economically, the insert bit should be pulled when the cost in $/ft begins to increase 20