A method of optimizing a geological model by scanning the hole angle

Abstract

This invention discloses a method for optimizing a geological model by scanning the well inclination angle. It aims to solve the problem of low efficiency and poor accuracy in directional drilling where the geological model inclination angle is constantly fitted to the actual drilling curve to correct the geological model. The core steps are as follows: Step 1: Establish a geological steering model for the current drilling based on the logging and structure of the completed well. Step 2: Set the actual logging curve of the drilling trajectory AB segment as the target curve, and extract the simulated curve from the geological steering model along this segment of the well trajectory. Step 3: Set the inclination scanning range 'a' and the scanning step size 'dlt', read the well inclination angle ∠A at point A, and perform an inclination scanning of the well inclination of segment AB with a step size of 'd1t' within the range of ∠A-a to ∠A+a, extracting the simulated curve from the model at each inclination angle. Step 4: Calculate the similarity between the simulated curve and the target curve using the similarity calculation formula within the range of ∠A-a to ∠A+a, and record the inclination angle difference when the similarity is the maximum. Step 5: Use the angle difference recorded in Step 4 to make the geological model angle after point A equal to the original angle plus the angle difference. Step 6: To ensure continuous model updates, calculate the inclination point forward from point A, thereby guiding directional drilling.

Description

I. Technical Field

[0001] In the energy industry, whether for saving land resources, rapid batch drilling, or the use of intensive offshore drilling and production platforms, directional drilling is undoubtedly the best drilling technology. In order to improve the reservoir encounter rate, reduce drilling risks, and improve economic benefits, geological steering technology is being increasingly used in the drilling process.

[0002] In order to better complete directional drilling in a region, pilot wells are often prioritized, or already completed wells are used as pilot wells to help study formation characteristics. The continuous characteristics of the formation within a certain area can be used to simulate the lateral formation distribution using pilot well logging sequences. The lateral formation distribution characteristics can be used to create a drilling geological model, and simulation curves can be extracted from the drilling geological model along the well trajectory. By comprehensively utilizing drilling-measured logging curves, simulation curves, and well trajectory factors, the dip angle of the formation can be studied to guide drilling operations. II. Background Technology

[0003] In addition to the drilling equipment being able to meet the drilling requirements of geological targets, directional well drilling also requires directional drilling technology to guide the drill bit to accurately locate geological targets in the underground space. Therefore, the geological model of the ongoing drilling can be studied using existing drilling data as a directional drilling model to guide directional well drilling.

[0004] The application of depth-domain seismic data largely eliminates the errors caused by variations in depth and thickness of formations along the longitudinal and transverse directions of the well trajectory. The steering model obtained by interpolating the square wave conversion of the guide well logging curves under the constraint of the depth phase axis can approximately represent the lateral distribution characteristics of the formations.

[0005] The calculation of the formation dip angle at each point in front of the drill bit, based on the well trajectory determined during the completed drilling section, is crucial to the success of the geological guidance in front of the drill bit. III. Summary of the Invention

[0006] The actual drilling logging curve is defined as the target curve, and the curve extracted from the directional model along this section of the well trajectory is called the simulated curve. In this well section, with the inclination angle at the starting point as the center angle, a well inclination angle scan is performed. At each scan step, the simulated curve is extracted from the directional model along the well trajectory. The simulated curve is then compared with the target curve, and the similarity between the simulated and target curves is calculated.

[0007]

[0008] x is the value of the simulated curve.

[0009] y is the target curve value

[0010] N is the number of sampling points for this trajectory segment.

[0011] cor represents similarity.

[0012] By analyzing the characteristic similarity between the target curve and the simulated curve, the well inclination angle with the highest degree of similarity is selected and recorded as the error angle of the model in that segment. This angle is used to correct the formation dip angle of the model.

[0013] Based on the principle that sedimentary rock strata are relatively stable within a certain range, the dip angle parameters of the strata in front of the drill bit can be inferred. IV. Description of the attached drawings

[0014] Figure 1 This is a schematic diagram of the well inclination angle scanning model.

[0015] Figure 2 These are the target well curve and the simulated curve.

[0016] Figure 3 It is the similarity curve within the tilt angle scanning range of point A.

[0017] (1) The completed section of the well being drilled; (2) Point A; (3) Point B; (4) The well inclination angle ∠A at point A; (5) The un-drilled section of the design well; (6) The maximum scanning angle a at point A; (7) The target well curve of section AB; (8) The extracted simulation curve; (9) The similarity curve between -a and a with point A as the center; (10) The maximum scanning angle; (11) The minimum scanning angle; V. Detailed Implementation Methods

[0018] A geological steering model for the ongoing drilling process is established based on logging and structural data from completed wells.

[0019] Set the actual drilling trajectory AB segment as the target according to the diagram in

[0009] , and read the actual drilling logging curve of segment AB.

[0020] Set the inclination scanning range a and the scanning step size dlt, read the well inclination angle ∠A at point A, and scan the well inclination of segment AB with dlt as the step size in the range from ∠Aa to ∠A+a with point A as the center. Extract the simulation curve from the model at each well inclination angle.

[0021] The simulated curve is resampled according to the sampling interval of the actual drilling curve to ensure that the target curve and the simulated curve have the same number of sampling points.

[0022] Within the range of ∠Aa to ∠A+a, the similarity between the simulated curve and the target curve is calculated using the formula

[0006] , and the difference in well inclination angle when the similarity is maximum is recorded.

[0023] The geological model after point A is corrected using the read well inclination angle difference.

[0024] To ensure the calculation results, the length of segment AB should not be too small, and is recommended to be more than 50 meters; the angle of dlt should not be too large, and is recommended to be 0.1 degrees.

[0025] To ensure the model is continuously updated, point A is calculated point by point forward according to the inclinometer points.

Claims

1. A method for optimizing a geological model by scanning well inclination angle, characterized in that: Step 1: Establish a geological steering model for the ongoing drilling based on the logging and structure of the completed wells; Step 2: Set the actual drilling logging curve of section AB of the drilling trajectory as the target curve, and extract the simulated curve from the geological steering model along this section of the well trajectory; Step 3: Set the inclination scanning range a and the scanning step size dlt, read the well inclination angle ∠A at point A, and scan the well inclination of segment AB with dlt as the step size in the range from ∠Aa to ∠A+a with point A as the center. Extract the simulation curve from the model at each well inclination angle. Step 4: Apply the similarity calculation formula within the range of ∠Aa to ∠A+a. cor is the similarity, x is the simulated curve value, y is the target curve value, and N is the number of sampling points for this trajectory segment. Calculate the similarity between the simulated curve and the target curve, and record the difference in well inclination angle when the similarity is the maximum. Step 5: Use the well inclination angle difference recorded in Step 4 to correct the geological model after point A; Step 6: In order to ensure that the model in front of the drill bit is constantly updated, point A is calculated point by point forward according to the inclination measurement points.

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