一种适合于川渝地区硬脆性地层的水基钻井液体系研究

A Kind of Water-Based Drilling Fluid System Suitable for Hard and Brittle Formation in Sichuan and Chongqing Area

摘要: 由于硬脆性地层具有较高的岩石硬度和脆性，钻井过程中易发生井壁坍塌、井眼不稳等问题，从而导致钻井效率低下，因此研究一种合适的钻井液配方来提高钻井液的抑制性和封堵能力，减少井壁坍塌和井眼不稳等问题是钻井过程中急需解决的难题。首先对川渝地区破碎性地层裂缝的特征进行分析，然后对该地层岩石初始的膨胀分散性能和加入不同流体之后的膨胀分散性能进行评价，室内配置了高性能水基钻井液的配方为：清水 + 3~5%膨润土 + 0.3~0.5% NaOH + 4~5% RSTF + 10%~15% JD-6 + 0.3~0.5% CaO + 5~7% KCl + 3~5% FRH (润滑剂) + 特级重晶石 + 1% HAR + 1% CJD-1 + 3% NFA-25 + 4% YRZ-1。并对所设计的钻井液配方进行性能测定，高温高压滤失量的测定和渗透性封堵实验两种评价方法都显示该配方的纳米封堵剂与微米级封堵剂之间共同作用，150℃下该配方的YP/PV值较高，钻井液有较好的流变性能和悬浮性能，该配方在120℃和160℃下的高温高压滤失量和滤失速率均有所降低，钻井液具有了良好的封堵性、抑制性和稳定性等性能。

Abstract: Due to the high rock hardness and brittleness of the hard and brittle formation, problems such as borehole collapse and borehole instability are prone to occur during the drilling process, resulting in low drilling efficiency. Therefore, it is an urgent problem to be solved in the drilling process to study a suitable drilling fluid formula to improve the inhibition and plugging ability of the drilling fluid and reduce problems such as wellbore collapse and wellbore instability. First, the characteristics of fractures in the broken formations in Sichuan and Chongqing were analyzed, and then the initial expansion and dispersion properties of the formation rock and the expansion and dispersion properties after adding different fluids were evaluated. The formula of high-performance water-based drilling fluid was developed as follows: clean water + 3~5% bentonite + 0.3~0.5% NaOH + 4~5% RSTF + 10%~15% JD-6 + 0.3~0.5% CaO + 5~7% KCl + 3~5% FRH (Lubricant) + premium barite + 1% HAR + 1% CJD-1 + 3% NFA-25 + 4% YRZ-1. The performance of the designed drilling fluid formula was measured, and the two evaluation methods of high temperature and high pressure filtration loss and permeability plugging experiment showed that the nano plugging agent of the formula and the micron-level plugging agent acted together, the YP/PV value of the formula was higher at 150˚C, the drilling fluid had good rheological properties and suspension properties, the filtration loss and filtration rate of the formula were reduced at high temperature and high pressure at 120˚C and 160˚C, and the drilling fluid had good plugging, inhibition and stability properties.