There is an absence of industry-wide, globally accepted standards that provide comprehensive inspection procedures and acceptance criteria for inspection and maintenance of drilling bits, including: wear, cracking, and mechanical damage criteria for bit bodies and cutting elements. Nevertheless, bits are routinely inspected and evaluated to determine their usability for both land and offshore drilling operations. This creates significant risk for all drilling operators because the lack of clear inspection criteria can lead to the use of bits with flaws causing downhole failures. In addition, the lack of an industrywide bit inspection specification has challenged bit suppliers since the decision to use a bit with indications and damage can be subjective and the potential risk severity can be high. Industry standards like API, ISO and DS-1 for inspection of other drill stem components do exist. However, the application of these standards to bits, particularly those with matrix bodies, is inappropriate. Using acceptance criteria adopted from existing standards for other drill stem components creates significant risk by accepting minor damage and rejecting major damage without an industry accepted standard. To overcome these limitations, a technical committee consisting of operators, drilling contractors, service providers, manufacturers, and inspection companies, worked together to develop specific procedures and acceptance criteria for the inspection of bit bodies as well as cutting elements. This paper presents the procedures and acceptance criteria developed by the technical committee that address the inspection of cracks and porosity in matrix and steel bit bodies, wear and erosion of bit bodies, cracks in PDC cutters, and other damage to cutters. The information included in this paper was considered for development of the DS-1 Bit Inspection Technical Standard (BITS) to address the necessity of a globally accepted standard for the inspection of bits.

C0Py119m 1987. SPE/lAOC 19S7 Dnllmg Gwlererwe Tlw~~r .8s grep.med tot presen!alton al the WS7 SPEilADC Drdlmg Comefswe fw!d m Wsw Orleans. LA. March 15-1!3, 19S7 Ths papw was sslscwd b presonwnon by an SPE/lADC Program lhnmmss IoUowng rsmsw 01 nWwIIIWmn contm!wd m an abstract subm!twd 8Y the 8uWX(S) Contents 01 the p2pRr as pre30nwfJ have not bssn rewewsd by the SOCSIIVof Pwmvwm Engmsem of ln!srnatmnal ASSCC,W.W of o@!. q Canhctws and am .9Ubfsctto Cormmon by the author(s) rb mawfw. as pm20nwd. doss 1101 nOcss.2ar,by&le.x any poslwm d ma IAK m SPE. Its OfEIcers.01 msmb.we PWS?S LWW.tsd at SPEIIADC msetmgs w s@pd m PUIXIIXUW by EIMOW1 COIMWWM L+ ,IW IAOC .IVJ SPE pm. nwsmm 10 copy IS rewiwea to an abstmcl o! no! more than 3X) words IIlu$lfa!we may no! w copted TIW abwr2c4 shoIJld c.amam C.Or@UJUOIJ$ w knowisdgmem cdwhere and by whom me papw,8 prewnwd Wme Publ$cahons Manager. SPE, P O Sox SSS8SS. Rfchardaon. TX 7S4S3.SS32 Twex. 730989 SPEDAL AesTItU3 the Wel 1 deca9anted cuttiagaction of HEC 1,2,3, 4,s.In the northern North Sea long This paper detai1s the results of a project to homogeneous clayatone sections proved ided PDC extend the range of POC bit application to fometions leading to ratee of penetration up to harder non-unifom foraations. These fomet ions three ti~a those obtainable by roller cone bits had previously proved difficult to drill with m.with greatly extended bit life. In these mass huge aavinga to the operntor were possible. The resulting design concept is out 1ined and the Teday over 70Z of the foetage of soae North Sea targeted fomat ions, field opereting paraeetem ,wIIs is drilled by PDC, with the percentage and perfomancea are illustrated with~phaaia rising year by year. Hmver, PM bits have on North Sea bit runs. renained foraation sensitive, perfoming beat tcuarde the softer end of the foraationa drilled The success of the project is shown In the 1,2,6+ To extend the econcmic range of PDC economic analysis.~e in the North Sea it was necessary to The result iaprove the performmce in harder and/or more is a new range of bits which have abrasive formations. exceeded their deaiSEE apecificat iona and significantly increased drilling efficiency During the firat half of 19SS a new bit design waa teatad in these harder foraations. This bit INTIKtDUm~w conaiated of a main PDC rotting structure with aaaecicated dimend impregnated back up studs. With the oil industry and particularly the North 'fheconcept wee teraed 'hybrid' to mhaaise the Sea facing SEEuncertain future, the advent of a duality of the cutting structure. 'ihiadual new high coat specialist drilling predh,.taey cutting atructure woo derived frcm SODS of the not sees an attractive propwit ion. However, early POC bits 7,15. operatora are having to beta ever sore efficient to ride out the almp by reducing These early b,ta used dieaond and PDC on the overall drilling costa. To this end any increeae in am radiua to eneure a raapectable bit life drilling efficiency hoe to be while the reliability and performecaof PDCwaa Welcemed. first being ev...

Ordinary least squares regression analysis is used to develop a model to forecast the Permian Basin rig count. Comparative analyses of various independent variables in linear, logarithmic and rate-of-change form indicate that approximately ninety percent of the variation in rig count can be explained using four independent variables. These variables represent Windfall Profits Tax, the maximum marginal personal income tax rate, crude oil price, and hourly wages of production workers in oil and gas extraction.

Ordinary least squares regression analysis is used to develop a model to forecast the Permian Basin rig count. Comparative analyses of various independent variables in linear, logarithmic and rate-of-change form indicate that approximately ninety percent of the variation in rig count can be explained using four independent variables. These variables represent Windfall Profits Tax, the maximum marginal personal income tax rate, crude oil price, and hourly wages of production workers in oil and gas extraction.