水平井多段水力压裂技术在伊拉克哈勒法耶油田的应用

Application of multi-stage hydraulic fracturing of horizontal well in Halfaya Oilfield, Iraq

伊拉克哈勒法耶油田Sadi油藏是中孔、特低—超低渗石灰岩油藏,因储层物性较差几乎未动用,借鉴国内外开发此类油藏的成熟经验,应用水平井多段水力压裂技术部署了S5H1井开展先导试验。在S5H1井的设计过程中,形成了“双甜点”评价技术:地质甜点评价技术主要通过开展岩石分类研究,综合地质成因相和岩石物理相的研究认识,优选出储层物性最好的地质甜点区域;工程甜点评价技术通过综合考虑脆性指数、杨氏模量、泊松比、最小水平主应力及断裂韧度,确定油藏不同区域易压裂程度,进而确定工程甜点。地质甜点和工程甜点紧密结合,对油藏进行分级评价,优选有利区域,确保了先导试验井的成功实施。S5H1井投产后初期日产油和1年累计产油分别是同油藏压裂直井的4倍和2.3倍,为Sadi油藏的整体开发打下了基础,也为中东地区同类型油藏的有效动用提供了参考。

Sadi oil reservoir, an ultra-low to super-low permeability limestone oil reservoir in Halfaya Oilfield, has barely been developed due to the poor reservoir property. Based on mature experience, pilot Well S5H1 has been deployed to test the feasibility of developing this type of oil reservoir by multi-stage hydraulic fracturing in horizontal well, and the evaluation technology of double sweet spots(geological and engineering) has been researched. The combination of rock type classification and the comprehensive understanding of geological genesis facies and petrophysical facies enables to establish the evaluation technology for geological sweet spot, so as to optimally select the favorable area with the best reservoir property. While the brittleness index, Poisson’s ratio, Young’s modulus, minimum horizontal principal stress and fault toughness are comprehensively analyzed to identify the reservoir fracability in various zones, so as to determine the engineering sweet spot. The close integration of geological and engineering sweet spots supports to evaluate the oil reservoir in different levels and select the favorable exploration area, which ensures the successful implementation of the pilot well. The initial production and cumulative production in the first year from Well S5H1 were 4 and 2.3 times of those in vertical well after fracturing, which laid a foundation for the overall development of Sadi oil reservoir and provided a reference for the benefit utilization of the same type of reservoirs in the Middle East.