Geosteering modeling method for automatically calculating stratigraphic dip angle

Abstract

The invention relates to the field of oil exploration, in particular to a geosteering modeling method for automatically calculating a stratigraphic dip angle, which comprises the following steps of: A, automatically establishing a plurality of geologic models corresponding to a plurality of stratigraphic dip angles by adopting a reference well reservoir section logging curve to align a drilling section; b, automatically generating a simulation curve corresponding to a stratigraphic dip angle by each geologic model in combination with a real drilling track; c, based on a morphological similarity guiding principle and a cross-correlation technology, automatically scanning a geologic model corresponding to each stratigraphic dip angle, and calculating superposed energy of each simulation curve and a real drilling curve; d, the stratigraphic dip angle corresponding to the maximum superposition energy is the model stratigraphic dip angle of the drilling well section; and E, calculating the stratigraphic dip angle of the model for each well section by adopting the steps. The problems of low precision and low efficiency caused by traditional manual judgment of the stratigraphic dip angle of the geologic model can be avoided, it is guaranteed that the drill bit is located at the optimal position of the reservoir all the time, and the drilling rate and drilling efficiency of the reservoir are improved.

Description

Technical Field

[0001] The invention relates to the field of petroleum exploration and development, and in particular to a horizontal well geosteering technology for automatically calculating formation dip angles. Background Art

[0002] Horizontal well geosteering technology is crucial in the development of oil and gas fields. Its main purpose is to control the wellbore trajectory in real time so that the drill bit can drill along the best position of the reservoir and improve the reservoir penetration rate. This can not only improve the productivity of a single well and extend the stable production period, but also reduce invalid footage and reduce operating costs. The core of geosteering technology is to obtain accurate model formation inclination to ensure precise direction control and effective drilling operations under complex geological conditions.

[0003] At present, there are two main types of geosteering technologies: the first is conventional horizontal well geometric steering technology, which is mainly achieved through well site selection, real-time monitoring (such as inclinometer) and drilling control; when adjusting the model formation inclination in real time, it mainly relies on real-time monitoring equipment such as inclinometer and formation pressure measurement to obtain the wellbore inclination data, and adjusts the angle of the drill bit and drilling parameters (such as drilling speed and feed rate) by analyzing the data and combining the operator's experience to achieve precise control of the inclination. This technology strongly relies on the operator's experience and judgment, increasing the risk of error caused by human factors. The other technology is layered steering interactive geological modeling technology, mainly represented by companies such as Baker Hughes and Schlumberger. This technology dynamically adjusts the drilling direction by integrating geological data, modeling and real-time analysis. In the technology, the tracking personnel manually adjust the simulation curve of the adjacent well to match the curve shape of the actual drilling logging and logging curve, thereby determining the formation inclination of the drilling section. Although the layered guidance technology provides better data support, the similarity of curve shapes leads to multiple solutions, which makes it difficult to make quick and accurate adjustments when manually processing real-time data. Especially when faced with complex formations, it is difficult to obtain accurate model formation inclination by manually comparing and observing similar curve shapes.

[0004] Based on the above mainstream geosteering technology relying on manual adjustment and experience to judge the model formation dip, resulting in low real-time processing efficiency and low formation dip accuracy, the present invention starts from the principle of maximum energy of similar curves and develops an automatic optimization model formation dip technology based on the superposition energy method, so as to achieve the purpose of improving the formation dip accuracy of the geosteering model, thereby improving the reservoir encounter rate. Summary of the invention

[0005] The technical problems to be solved by the present invention are: In view of the shortcomings of the prior art, a method for automatically calculating the formation dip of a geological model and improving the formation dip accuracy is provided.

[0006] The technical solution of the present invention is: A method for automatically calculating the formation dip angle, the original data of which is: a sampling point number is N, the vertical depth range is , The reference well logging curve is denoted as The number of sampling points is M, and the offset range is , The actual drilling trajectory of the drilling section is recorded as , The LWD curve of a drilling section with a sampling point number of P and an offset range that is the same as the actual drilling trajectory is recorded as .

[0007] The steps for automatically calculating the formation dip include: A. Using the reference well reservoir section logging curve The offset range is , Establish a geological model for the drilling section and set the formation dip range for the drilling section , , according to the formation dip angle, the model starting vertical depth of the logging curve changing with the offset distance is calculated as: in, is the vertical depth corresponding to the maximum offset of the current well depth section, is the vertical depth corresponding to the maximum offset of the previous well section, which can be expressed as the trigonometric function relationship between the current well depth section and the formation dip angle of the current structural point. is the maximum offset distance of the current well section, is the maximum offset distance of the previous well section, is the xth formation dip. By analogy with this relationship, the logging curve is used to fill the model based on the vertical depth of the previous well section, and a geological model is established for each formation dip. , .

[0008] B. When calculating the curve value of the actual drilling trajectory in each geological model, first calculate the intersection of the sampling point of the actual drilling trajectory and the logging curve, and take the value to generate a simulation curve. The formula for taking the value of each sampling point in the trajectory in the logging curve is as follows: in For a vertical depth of Based on the current well section The corresponding vertical depth change; For the trajectory The vertical depth corresponding to the offset distance, is the vertical depth of the intersection of the trajectory sampling point on the logging curve, and its value is , thus generating The corresponding simulation curve And so on, generate the simulation curve corresponding to each model , .

[0009] C. Calculate the superposition energy of each simulated curve and the actual drilling curve, which includes two steps: first, resample the simulated curve of m sampling points to generate a curve of P sampling points, the formula is as follows: , ,in is the location of the new sampling point, Indicates rounding down. Indicates rounding up. , They are the values ​​of two adjacent points in the original simulation curve.

[0010] For each simulation curve, a new simulation curve with P sampling points is generated by interpolation using the above formula: , , respectively, and make cross-correlation calculations with the actual drilling curve to calculate the superposition energy. The formula is as follows: In the formula, is the superposition energy of the ith simulation curve, is the x-th formation dip; is the curve value corresponding to the mth offset in the actual drilling curve; is the curve value corresponding to the mth offset in the simulation curve.

[0011] D. Calculate the stacking energy corresponding to each formation dip , Then, the maximum superposition energy is screened Corresponding formation dip is the optimal formation inclination in the drilling section; E. Use the above steps to calculate the model formation inclination for each well section.

[0012] Among them, steps A, B, C and D are the innovative points of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the basic steps of the present invention; Figure 2 The geological stratification for the gamma curve of the reference well; Figure 3 The gamma curve of the reference well from the top of Long-14 to the bottom of the Wufeng Formation used to establish the geological model; Figure 4 This is a color map of the stratigraphic layers from the top of Long-14 to the Wufeng Formation; Figure 5 Geosteering model for artificial adjustment of formation dip; Figure 6 A geosteering model for automatically calculating formation dip. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and examples.

[0015] Embodiment 1 Figure 1 A schematic diagram of specific steps for implementing the present invention is provided, and the specific implementation steps can be described in detail as follows: Step 1: Use the logging curve of the reservoir section of the reference well to align the drilling section and establish a geological model corresponding to multiple formation dips; Step 2: Each geological model is combined with the actual drilling trajectory to form a simulation curve corresponding to the formation dip; Step 3: Based on the morphological similarity-oriented principle, calculate the superposition energy of each simulation curve and the actual drilling curve; Step 4: The formation dip corresponding to the maximum stacking energy is the model formation dip of the drilling section; Step 5: Use the above steps to calculate the model formation dip for each well section.

[0016] Embodiment 2 The present invention is used to carry out geosteering modeling of shale gas horizontal wells and conduct comparative analysis.

[0017] Figure 2 The application effect of the geosteering of the present invention in the Qingyuxi block is given. The data are all well logging data of the Qingyuxi block. The horizontal well is a shale gas well with complex geological conditions and great tracking difficulty. The target layer of the well is buried at a depth of about 4,000 meters, the target layer is about 3 meters thick, the horizontal section is about 2,300 meters long, and the target reservoir is from the top of Long-11 to the top of Wufeng Formation. The offset distance of the adjusted well section is 935 meters to 967 meters (AB well section), the adjustment point is point B, and the formation dip angle adjustment range is -10 degrees to 0 degrees. Figure 2 , Figure 3 Well logging curves for establishing geological models. Figure 4 It is the geological layer color, which is used to determine the stratigraphic position of the actual drilling trajectory in the model.

[0018] Figure 5The geological model obtained by artificially adjusting the simulation curve has a formation dip of -5.25 degrees and a stacking energy of 0.989. The adjusted simulation curve (dashed line) and the actual drilling curve (solid line) are consistent in shape. From the color analysis of the actual drilling trajectory in the formation position, the actual drilling trajectory is still in the Long-11 reservoir, but from the analysis of the actual drilling logging curve, the drill bit has entered the Wufeng Formation layer (through the target reservoir), so the adjusted geological model does not match the actual situation.

[0019] Figure 6 The geological model obtained by automatically calculating the maximum stacking energy of the present invention has a formation dip of -6.05 degrees and a stacking energy of 0.991. The adjusted simulation curve (dashed line) and the actual drilling curve (solid line) are not completely consistent in shape. From the color analysis of the actual drilling trajectory at the formation position, the actual drilling trajectory has entered the Wufeng Formation formation (passing through the target reservoir), which is consistent with the conclusion of the actual drilling logging curve analysis. The adjusted geological model is consistent with the actual situation.

[0020] The above embodiments have strongly demonstrated the beneficial effects of the present invention: by automatically calculating the formation inclination, the efficiency and accuracy of real-time adjustment of the formation inclination are improved, the errors caused by manual adjustment are avoided, the geological position of the drill bit in the reservoir is effectively indicated, and a strong support basis is provided for drilling implementation.

Claims

1. A geosteering modeling method for automatically calculating formation dip angle, characterized in that: The method comprises the following steps: A. Use the logging curve R(h) of the reservoir section of the reference well to establish a geological model. Given the formation dip range of the drilling section, each formation dip corresponds to a geological model; B. Calculate the curve value of the actual drilling trajectory in each geological model, and generate a simulation curve for each model; C. Calculate the superposition energy of each simulation curve and the actual drilling curve, which includes two steps: C1. Resample the simulation curve to make the number of sampling points of the simulation curve consistent with the number of sampling points of the actual drilling curve; C2. Perform cross-correlation calculation between the simulated curve and the actual drilling curve, and the sum of the calculations is the superposition energy; D. Selecting the model formation inclination corresponding to the maximum stacking energy as the optimal formation inclination of the drilling section; E. Use the above steps to calculate the model formation inclination for each well section.

2. The method for geosteering modeling for automatically calculating formation dip angle according to claim 1, characterized in that: The logging curve R(h) of the reservoir section of the reference well in step A includes one of the following curves: a gamma curve and an element curve.

3. The method for geosteering modeling for automatically calculating formation dip angle according to claim 1, characterized in that: The method for calculating the curve value of the actual drilling trajectory in the geological model in step B includes the following methods: according to the coordinates (x, y) of each trajectory point in the actual drilling trajectory, where x is the horizontal offset distance of the trajectory point and y is the vertical depth of the trajectory point, calculate the corresponding curve value in a single geological model to generate a simulation curve of the model; perform the same calculation for each model to generate a simulation curve corresponding to the model.

4. The geosteering modeling method for automatically calculating formation dip angle according to claim 1, characterized in that: The method for calculating the superposition energy of the simulation curve and the actual drilling curve in step C includes the following method: each simulation curve is calculated by resampling interpolation to generate a simulation curve consistent with the sampling interval and sampling point number of the actual drilling curve of the current well section, and the superposition energy is calculated by cross-correlation respectively.

5. The method for geosteering modeling for automatically calculating formation dip angle according to claim 1, characterized in that: The geosteering modeling method for automatically calculating formation dip angles comprises the combined use of five steps: A, B, C, D, and E.

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