苏5-15-17AH井超3000m水平段的钻井技术

Drilling techniques for an ultra-long horizontal interval (>3000m) in Well Su 5-15-17AH in the Sulige Gas Field,Ordos Basin

苏5-15-17AH井是部署在鄂尔多斯盆地苏里格气田的一口超长水平段水平井,设计水平段长度3 000m,长水平段水平井的摩阻及扭矩大、井眼清洁困难及完井方式有限等成为该井的主要技术难点。为此,开展了以下试验研究:①通过优化井身结构,利用套管内摩擦系数小的特点来降低水平段钻进的摩阻与扭矩,选择在φ215.9mm井段钻进水平段1 200m,下入φ177.8mm套管固井,然后在φ152.4mm井段钻进水平段1 800m;②无土相复合盐钻井液体系及强封堵油基钻井液的应用,有效地解决了超长水平段井壁稳定性差、井眼清洁难度大及摩阻大的难题,确保了长水平段的顺利施工;③应用漂浮接箍工具使其下部套管入井后受到钻井液的浮力作用,降低了井壁对套管柱的摩擦阻力,确保了φ177.8mm套管顺利下入井底。该井完钻井深6 706m,实际完成水平段长度达3 056m,创目前国内陆上天然气水平井最长水平段纪录,对今后苏里格气田以及类似地区施工长水平段水平井有借鉴和指导作用。

Deployed in the Sulige Gas Field, Ordos Basin, Well Su 5-15-17AH is a horizontal well with an ultralong horizontal interval, a design length of which is 3,000 m. There are great challenges for such a long horizontal well such as large friction and torque, difficult borehole cleaning, limited completion methods, etc. In view of this, the following tests and studies were performed. First, through the optimization of wellbore configuration, the friction and torque were reduced by the small friction coefficient inside the casing during drilling in horizontal intervals. A horizontal interval of 1,200 m was drilled in the φ215.9 mm well section, a φ177.8 mm casing was run for cementing, and another 1,800 m horizontal interval was drilled in theφ152.4 mm well section. Second, by use of the clayfree compound salt drilling fluid system and oil base mud, such difficulties were effectively solved as poor wellbore stability, difficult wellbore cleaning and large friction, which ensured the smooth construction of long horizontal intervals. Third, with a float collar, the casing below the collar was supported by the buoyancy of the drilling fluid; therefore, the friction between the wellbore and casing string was reduced, so the φ177.8 mm casing was smoothly run down to the well bottom. The total depth of the well was 6,706 m, and the actual completed length of the horizontal interval was 3,056 m, recording the longest horizontal interval of onshore gas horizontal wells in China. This case study provides reference and guidance for horizontal wells with ultralong horizontal intervals in the Sulige Gas Field and other similar fields.