珠江口盆地XJ油田薄油层水平井三维地质导向技术

针对XJ油田薄油层厚度小、砂体展布特征不确定、岩性变化快和井眼轨迹出层风险大等问题，开展了薄油层水平井三维地质导向技术研究。通过沉积微相精细描述明确砂体展布特征，深入研究储层岩性特征，建立精细地质模型，并充分应用地层边界探测仪、结合其他测录井资料，准确判断井眼轨迹在目的层中的位置，预测地层变化情况。研究表明，XJ油田薄油层中浊积砂体多呈条带状分布，厚度大于前缘席状砂体，是水平井部署的有利相带；沉积微相分布对储层岩性有重要影响，沉积微相约束下建立的岩相模型能准确预测水平井所钻遇地层岩性；地层边界探测仪能获得井眼轨迹周围较大范围内的地质特征，可有效指导油层中的水平井钻进。该技术在XJ油田油层厚度小于5.00 m的3口薄油层水平井进行了应用，储层钻遇率均高于90%。研究与应用表明，XJ油田薄油层水平井三维地质导向技术应用效果良好，对其他地区的薄油层地质导向钻井具有很好的借鉴作用。 

Three-Dimensional Geosteering Horizontal Drilling Technique in Thin Reservoirs in the XJ Oilfield,Pearl River Mouth Basin

Thin reservoirs in the XJ Oilfield are characterized by minor thicknesses, uncertainty in distribution, fast changes in lithologic features and a high risk of drilling out of the target formation. Accordingly, 3D geosteering horizontal drilling technique has been developed. Through in-depth study over lithologic features of the reservoir formations, a detailed geological model has been constructed. At the same time, by taking full advantage of a formation boundary detector and other logging and well logging data, positions of borehole trajectory in target formation could be predicted accurately to predict changes in formation properties. Research results showed that turbidite sand bodies were mostly distributed in strips with thicknesses higher than the frontal sheet sand. Consequently, these formations were favorable for deployment of horizontal wells. Since the distribution of sedimentary microfacies might greatly affect lithologic features of reservoir formations, the lithologic model constructed under the constraint of sedimentary microfacies could effectively predict lithologic features penetrated by horizontal drilling. At the same time, the formation boundary detector could be used to acquire geologic features over large areas around the borehole trajectory, and accordingly, could effectively guide the drilling of horizontal wells in pay zones. The newly developed technology was deployed in three horizontal wells drilled in thin reservoirs with thickness no more than 5.00 m in the XJ Oilfield. The average penetration rate achieved was 90%。Research results and application performances showed the 3D geosteering horizontal drilling technology of in thin reservoirs of XJ Oilfield had outstanding performances and might provide valuable guidance for geosteering drilling operations in thin reservoirs of other areas.