深井高密度盐水钻井液流变性控制技术

肯基亚克盐下油田属高压油气藏,石炭系灰岩油层孔隙压力系数高达1. 90~1. 94,裂缝发育,漏喷同层,钻井液安全密度窗口窄,极易出现先漏后喷的复杂局面,钻井液流变性成为影响井下压力平衡的重要因素。高密度盐水钻井液因固相含量高、固相容量限低,流变参数总体上偏高,调整和控制较为困难。在分析各种影响因素的基础上,建立了一套以控制劣质固相、维持化学抑制性和等浓度维护为核心的高密度盐水钻井液流变性控制技术。经肯基亚克盐下油田20多口井的现场应用,取得了流变参数大幅度下降,流变性显著优化的效果。

RHEOLOG ICAL PROPERTY CONTRAL TECHNOLOGY FOR H IGH DENSITY SALT DRILLING FLUID

Reservoirs in“КенКияк”oilfield are high pressured reservoirswith oil formation pore pressure coefficients between 1. 90 -1. 94. Because carbonate rock in Carboniferous system which wasmain reservoirs develop many cracks that caused not only mud loss but alsowell kick, and had narrow safety densitywindow of drilling fluid, first lost circulation then well blowout is easily to happened, so drilling fluid rheological property became as the important factor of affecting pressure balance in wel.l But high density saltdrilling fluid with high solid phase content and low solid capacity limitgenerally possess high rheologicalparameter, therefore itwas difficult to contro.l Based on analyzing the influence factor, a setofsystematic technologies for control rheological property of high density salt drilling fluid were proposedthat included: elimination of solid pollution; maintenance of chemical inhibitive characteristic; stabilization of salt content and low pH. By adopting these technologies in three well drillcal propertywas obviously improved.