伊拉克H油田Sadi油藏鱼骨井井眼布置方案研究

Wellbore Arrangement Schemes for Fishbone Wells in the Sadi Reservoir of the H Oilfield in Iraq

为有效开发伊拉克H油田特低渗透油藏Sadi油藏,针对该油藏的特征和鱼骨井钻井条件,综合考虑地质、油藏及工程因素,进行了鱼骨井井眼布置方案优选方法研究,以获得既能满足开发要求又能在极限钻井条件下顺利钻井的鱼骨井井眼最优布置方案。以Sadi油藏地质条件和常规定向井钻井能力为基础,确定了鱼骨井主井眼及分支井眼的极限钻井深度;以累计产油量为目标,分析了鱼骨井主要参数(分支井眼数量、分支井眼长度、相邻分支井眼的间距、分支井眼与主井眼夹角)及不同鱼骨井井眼布置方案对累计产油量的影响,确定出累计产油量较高的井眼布置方案;以鱼骨井不同井段井眼轨道的钻井难度,建立相应模型评价了鱼骨井井眼不同布置方案的钻井风险,确定出钻井成本较低的井眼布置方案,最后优选出4分支井眼、分支井眼长730.00 m和3分支井眼、分支井眼长800.00 m的最优井眼布置方案。采用优化的井眼布置方案,累计产油量较高,钻井风险可控,钻井成本低。提出的鱼骨井井眼布置方案优选方法将钻井工程和地质油藏工程紧密结合,为油藏工程师优选鱼骨井井眼布置方案提供了思路,并为其他相似油藏进行鱼骨井井眼布置方案设计提供了借鉴。

In order to effectively develop the Sadi ultra-low permeability reservoir, the optimal method for arranging fishbone well schemes was studied in accordance with the characteristics of reservoir and the conditions of fishbone well drilling, by comprehensively considering the reservoir geology and engineering factors. as the goal was to obtain the optimal fishbone well arrangement scheme that can satisfy the need for both development and smooth drilling under extreme drilling conditions. First, the ultimate drilling depths of the main wellbore and branch hole of the fishbone well were determined based on the geological conditions of the Sadi reservoir and the drilling capacity of conventional directional wells. Then, by taking the cumulative oil production as the preferred target, the influences of main parameters(such as the number of branch hole, the length of branch wellbore, the spacing between adjacent branch holes, the included angle between the branch hole and main wellbore, and different fishbone wellbore deployment schemes) on the cumulative oil production were analyzed to determine the wellbore deployment scheme with higher cumulative oil production. Next, according to the drilling difficulty of different trajectories of the fishbone well, a corresponding model was established to evaluate the drilling risks of different wellbore deployment schemes and determine the scheme with lower drilling cost. Finally, the wellbore arrangement schemes for 4 branch hole length of730.00 m and 3 branch hole length of 800.00 m were selected as the best schemes for the fishbone well of the Sadi reservoir. The application of the optimal wellbore arrangement scheme has provided high cumulative oil production,with controllable drilling risk and lower drilling cost. The proposed optimal method of fishbone well arrangement schemes combined closely the drilling engineering and the reservoir engineering geology, so as to provide the reservoir engineer an idea of selecting a fishbone well arrangement scheme, and to give a reference for design of fishbone wellbore for similar oilfields.