Handing of influx-leakage coexisting complication in asphalt formation of Well F13 at the Yadavaran Oilfield

Well kick induced serious asphalt invasion and infux-leakage coexisting encountered on F13 well at Yadavaran Oilfeld in Iran during drilling at the long open-hole section in the formation of Kazhdumi. It's the frst time to deal with this kind of invasion and infux-leakage coexisting and the referred literature and treatment method was limited. After trying many times tough and exploratory treatment but failed, such as 9 times conventional plugging and killing by different mud weight and LCM recipe and two times reverse-squeezing plugging and killing, the strategy that F13 well frstly be sealed by cement plug and then sidetracked into a horizontal well by switching the geology target zone from Fahliyan into Sarvak formation was forced to be applied. It detailedly presents the occurrence and treating process of the invasion and infux-leakage coexisting, the reasons for failure of treatments and consideration for selecting sodium silicate accelerating agent of cement. On the basis of lab experiments, the sodium silicate with spacer to accelerate cement thickening was used in cement plugging operation with asphalt pollution existing. Field application shows that this method was effective and feasible to conduct cement plugging operation with asphalt pollution. The experience and lesson learnt from this well and the innovated method that sodium silicate with spacer to accelerate cement thickening provide valuable reference for smooth drilling at Kazhdumi formation of follow-up operations in Yadavaran Oilfeld.