The Challenges and Way Forward of Horizontal Dual Lateral Wells in Fahud Matrix Reservoir

摘要

The Fahud field, on stream since 1967, is being the largestrnfield in Oman in term of STOIIP 1x10(9) m3. This greatrncarbonate field, initially produced by natural depletion,rnfollowed by gas injection in 1968, water flooding drive inrn1972 and is now being produced by gas- oil gravity drainagernprocess (GOGD) since 1984. The field once thought to berncompletely covered with fractured reservoir, hence onlyrnGOGD development with crestal gas injection for voidagernreplacement has recently being also developed by waterrnflooding in Shuiaba and Natih matrix reservoir.rnThe dual lateral completion aims to maximize the productivityrnfrom relatively low permeability matrix units. The two lateralsrnare normally completed barefoot (Level 2 multilateral) with arnsingle selective 3 ?” gas lift completion. As completion staysrnsimple and cost effective, lateral re-entry remains one of thernmain challenge. Different technologies have been applied tornaddress various completion challenges in these dual laterals,rnwith various degrees of success. For instance a pre-milledrnsecure window at the junction to allow upper lateral re-entryrnhas been applied with technical success but hindered 7” linerrncementation. Other areas that have been atried in dual lateralsrnare improving acid stimulation techniques, liftingrnoptimization, improving well design to overcome holernproblem, improve liner cementation, producing andrnmonitoring each lateral, etc. at different degrees of success.rnThis paper is intended to cover all these major challengesrnfacing Fahud horizontal dual lateral wells matrix reservoirs,rntechnologies applied and their outcomes (success and failures),rnand foreseen future completion issues in term of subsurfacerncharacteristics uncertainties and way forward. Given such arnlarge STOOIP, and the fact that GOGD process has slow andrnlow recovery factor, maximizing these low permeabilityrnmatrix units is essential for the field production.