The MacCulloch oilfieldliesinBlock 15/24b inthe UK CentralNorthSea.The fieldisproduced usinga floatingproduction storage andofftake facility from two sub-sea centresandhasbeenonproduction since 1997.The originalgeophysicalmappingofthe fieldwasbased on 3Dseismic dataacquired in1993. InApril2002,a repeat3Dsurveywasacquired overthe fieldwiththe aimofbetterunderstandingthe depletion ofthe fieldusing time-lapseseismic analysis.The MacCulloch Fieldreservoirs areturbiditesofthe UpperBalmoralSandstoneUnitinthe ListaFormation of the UpperPaleocene, which areconnected to alarge aquiferinthe underlyingLowerBalmoralSandstoneUnit. Connection to such alarge aquifermeans thatpressuresupport overfieldlife hasbeenvery good( , 100 psidrop overfieldlife). Thisfact,coupled withthe lack ofagascap,means thatfor the time-lapseanalysisany change shouldprimarily be dueto asubstitution ofwaterfor oil.The MacCulloch Fieldreservoirismade up offivediscreteturbiditesandstone-dominated sandbodies,which canbe distinguished on the seismic data.Examination ofthe time-lapseresponseinthesebodiesshows thatthey haveacted asaprimary control on the depletion ofthe field.The individualbodieshavebeenanalysed using3D visualization andi nterpretation techniques,a ndi ncorporated into the geologicalm odelw ithd ifferingrock propertiesassigned to each.Withinthe reservoirsimulation model,the assignment ofdirectionalpermeabilitiesto theseunits andthe placingoftransmissibility barriers attheirboundariessubstantially improved the history match ofthe field, therebyenhancingour ability to predictfutureperformance andi dentifyp ossiblei nfill drilling locations.
Hole enlargement while drilling (HEWD) is now widely used in deepwater applications. It provides reduced-clearance casing programs, improves drilling in swelling formations, and helps equivalent circulating density (ECD) management. HEWD applications commonly use an underreamer in a BHA with a rotary steerable system (RSS). Currently, traditional reamer placement results in a long portion of unenlarged hole—rathole—which requires an extra trip to enlarge. A new BHA design is being sought to eliminate the second trip requirement—the objective is to find a feasible solution. Placing the reamer closer to the bit would forgo the need for a second trip; however, the placement of a traditional reamer is limited by its design. In response to such limitation, a solution is proposed to design a rathole elimination (RHE) BHA which includes a lower reamer placed between MWD/LWD tools and the RSS. During HEWD, the lower reamer is in passive (off) mode while a traditional reamer is active. Upon reaching TD, the BHA is tripped back to position the lower reamer above the rathole and is then activated to enlarge the rathole. This RHE BHA design thereby eliminates the second trip requirement. This paper discusses the operational learnings and drilling performance of the proposed RHE BHA design. A field test in Texas is presented and documents the downhole dynamic performance of the single-trip BHA. Drilling dynamics measurement modules (DDMM) were positioned near the reamers to measure the downhole drilling dynamics. This run captured data for traditional HEWD operations and rathole elimination operations. To ensure stable drilling operations, a time-based dynamic simulation perfomed a prerun parametric sensitivity study to help identify the optimal parameters that could deliver high ROP, low vibration, and low stick-slip. A roadmap was made for operational guidelines based on simulation analysis. The test was successfully completed with stable HEWD and RHE operations observed. After completion of the run analysis of the DDMMs, measured downhole dynamic data showed stable downhole drilling dynamics during both HEWD and RHE operations. The RHE operation generated similar levels of vibration and stick-slip at the reamer and MWD/LWD tools compared with the HEWD operation. This field test shows that a single-BHA design can deliver stable drilling dynamics in both HEWD and RHE operations, and demonstrates the capability of the solution in eliminating the second trip requirement. This single-trip RHE BHA design will not only reduce operational costs, but will also lower HSE risk by enabling less BHA handling on the rig floor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.