Drilling Hazard Mitigation-Utilizing Solid Expandable Liners to Address Trouble Zoneswith Zero Hole Size Loss

摘要

Mitigating drilling hazards has been challenging cost-effectivernwell construction for decades. Balancing drilling risks againstrnthe optimum well design while preparing for unplannedrndrilling events combine to be a never-ending set ofrnfrustrations. The operator’s authorization for expendituresrn(AFE) can be significantly impacted when he is fighting porernpressure/formation fracture gradient challenges or unexpectedrnshallow flows, unstable formations, overpressure formationsrnor depleted formations are encountered.rnExcessive use of lost-circulation pills, and traditionalrncontingency liners drive well costs up and jeopardizesrnreaching total depth (TD) with an effective completion. Arndrilling hazard mitigation solution could be as simple as usingrnthat contingency liner that was planned into the well, or thernuse of drill-in casing to fight an unstable wellbore. However,rnthe use of conventional solid expandable drilling liners canrndrive excessive risks into the well and even cause a costlyrnsidetracking of the well.rnOperators in the former Soviet Union (FSU) have beenrnsuccessfully using short expandable openhole clad-thru-cladrnliners for decades to cost-effectively mitigate expected, andrnunexpected, well construction challenges. These systems arernused only when necessary and cover only the trouble zone,rnallowing the well construction to continue without the loss ofrnany hole size. Operators have used these solid, expandablernsystems as “Steel MudcakeTM,” minimizing the risk of usingrnsolid, expandable liners.rnThis paper describes applications where this alternativernsolid expandable liner system has been used over the yearsrnand how a wide variety of well construction challenges havernbeen addressed without the need for downsizing a wellrnsection.rnShort, low-risk, openhole, expandable liners have beenrnused to address drilling hazards during the well constructionrnprocess, allowing continued, post-remediation drilling of thernwell with the same size bit. Because there is no loss of holernsize through the use of these openhole “clad” liners,rnsubsequent drilling hazards in the same-size hole section canrnbe remediated without downsizing the wellbore.rnInstalling field-proven, short, solid, expandable, openholernclad liners minimizes operational risks and reduces the cost ofrnthese expandable systems. Minimizing the “flat” time on therndrilling curve has allowed operators to continue the wellrnconstruction process quicker, reducing rig time and cuttingrnwell construction costs.rnDiscussion of how risks have been driven out of thernexpandable drilling hazard mitigation product and casernhistories will be reviewed for several applications. We willrnalso discuss how this and other conventional and nonconventionalrnhazard mitigation “tools” can be used separatelyrnand in conjunction with one another to significantly reducernwell construction risks and reduce well costs.