碳酸盐岩薄储层水平井随钻录井评价方法

四川盆地广泛分布着低孔隙度、低渗透率的碳酸盐岩薄储层，采用水平井钻井工艺能最大限度地揭示储层、提高单井产能，但如何才能主导水平井轨迹在薄储层中钻进却一直是地质导向工作的难点。在川渝地区第一口地质导向井（M-24井，其目标储层为中三叠统雷口坡组T₂l₁¹针孔状白云岩段）的钻进过程中，鉴于随钻测井仅能提供随钻伽马数据，储层的判别须以录井参数为主导，而目前录井储层评价方法欠缺，故有必要对此开展研究。首先对能作为储层有效判别依据的录井参数进行了综合研究，优选出岩屑、钻时、气测值、自然伽马等参数作为储层有效判别的依据；在准确识别出正钻地层岩性的基础上，结合实钻资料（钻时和气测值），进一步对储层进行识别与划分，并在随钻评价过程中，及时利用录井解释结果提供导向决策，引导水平井在储层中钻进。最后，将随钻录井评价结论与钻后测井解释结论进行了对比，结果表明，二者结论基本一致，仅在储层段顶底深度略有差异，证实了随钻录井评价方法的实用性和准确性。

MWD analysis of thin carbonate reservoirs in horizontal wells

Thin carbonate reservoirs with low permeability and porosity are widely distributed in the Sichuan Basin. Horizontal drilling can maximize the volume of these thin reservoirs in contact with wellbore, thus improve single well productivity. However, how to keep the horizontal well trajectory going within the thin reservoirs is a big challenge to geosteering. During the drilling of the first geosteering well M-24 targeting the payzone of the needle like dolomite reservoir T₂ l₁¹ in the Middle Triassic Fm, Sichuan Basin, reservoir discrimination had to mainly rely on logging parameters and the logging while drilling (LWD) could only provide Gamma ray data, so it is necessary to perform studies on the mud logging while drilling (MWD) evaluation method. Composite logging parameters were studied first to select multiple parameters including cutting logging, drilling time logging, mud logging and Gamma ray as effective basis of reservoir identification. Based on the real time accurate identification of the lithologies of strata as well as the real drilling data (drilling time and gas logging value), reservoirs can be identified and divided. During evaluation while drilling, the logging interpretation can be used to guide real time geosteering and help keep the horizontal well trajectory going within the thin reservoirs. A comparison of the results of evaluation while drilling with the post drilling logging interpretation reveals that they are basically the same, verifying the practicality and accuracy of the MWD evaluation methods.