## 3 Method and Experiment  
### Material Selection  
In order to measure the actual fracture pressure of the weathered clay layer, it is necessary to accurately divide the unconformity three-layer structure, find the location of the weathered clay layer, and collect the core. The unconformable structure is generally divided into rocks on the unconformable surface (upper layer: mainly bottom conglomerate or sandstone, which is formed by deposition after transportation from different places under the action of running water), weathered clay layer (middle layer: located in the upper part of the ancient weathering crust, the lower part of the rock after the formation of sedimentary uplift, the product of leaching deposition), and semi-weathered rock (lower layer: weathering leaching zone) (Figure 2a). According to the causes of unconformity, the unconformity structure has great differences in radioactivity, electricity, and elasticity. Compared with normal deposition, GR and SP logging curves should show an increasing trend because of the increase in clay composition and radioactivity. Because of fluid loss and weak conductivity, the R logging curve shows a decreasing trend; the leaching effect of the weathering crust reduces the elastic wave velocity of the rock, and the AC curve shows an increasing trend [7,10]. Therefore, the upper, middle, and lower layers of the unconformity structure show different logging response characteristics. The upper layer: the GR and SP logging curves exhibit an equal-amplitude cross type, the AC and DEN logging curves are of the zigzag box type, the R logging curves show a wide range of regular increases and decreases, CNL shows more regular increases and decreases; the middle layer: compared with the upper SP curve, the GR and AC curves increase markedly, the DEN logging curve decreases significantly, the R logging curve changes significantly and tends to stabilize, CNL increases and decreases slightly in the lower layer: the SP curve increases gradually, the GR curve changes significantly, the AC and DEN logging curves tend to coincide, the R logging curve increases and decreases in a zigzag shape, and CNL increases and decreases more than the middle layer (Figure 2b). Figure 1: The geographical location map of Mahu Sag and Ma131 well area (**a**) and the division map of tectonic units (**b**) in the Junggar Basin. In order to accurately divide the three-layer structure of unconformity, five basic curves of \(AC\), \(DEN\), \(SP\), \(RT\), and \(GR\) are selected based on the response characteristics of different logging curves. Due to the different dimensions of each curve, it is normalized to avoid too large numerical differences and affect the accuracy of the results. Using the Max-Min normalization method, the \(GR\) and \(AC\) curves increase in the weathered clay layer, with the minimum value of the curve selected as the reference. Conversely, the \(DEN\), \(SP\), \(RT\), and \(GR\) are selected based on the response characteristics of different logging curves. Figure 2: Types of micromigration channels of unconformity structures (**a**) and logging response characteristics (**b**). \(SP\), and \(RT\) curves decrease in the weathered clay layer, with the maximum value of the curve chosen as the reference, as shown in Equation (1). \[\left\{ \begin{array}{l}\Delta AC=\frac{AC-AC_{\min}}{AC_{\max}-AC_{\min}}\\ \Delta DEN=\frac{|DEN-DEN_{\max}|}{DEN_{\max}-DEN_{\min}}\\ \Delta SP=\frac{|SP-SP_{\max}|}{S\hat{P}_{\max}-SP_{\min}}\\ \Delta RT=\frac{|RT-RT_{\max}|}{RT_{\max}-RT_{\min}}\\ \Delta GR=\frac{GR-GR_{\min}}{GR_{\max}-GR_{\min}}\end{array} \right. \tag{1}\]  
In the formula, \(\Delta AC\), \(\Delta DEN\), \(\Delta SP\), \(\Delta RT\), \(\Delta GR\) are the results after the normalization process of five curves of acoustic wave time difference, density, \(SP\), resistivity, and natural gamma, respectively.