Method for reservoir assessment by calculating logging porosity while drilling by utilizing data during micro drilling

Abstract

The invention discloses a method for reservoir assessment by calculating logging porosity while drilling by utilizing data during micro drilling. The method comprises the following steps of: (a) collecting data during the micro drilling of drilled wells; (b) establishing a correlation model of the data during the micro drilling and formation porosity data by combining the data during the micro drilling of the drilled wells and the corresponding formation porosity data; (c) according to the established correlation model of the data during the micro drilling and the formation porosity data, calculating the logging porosity while drilling by utilizing data during the micro drilling of a well drilled at present; and (d) setting a formation porosity of a conventional dense lithological section to be a default which is lower than the lower limit standard of the formation porosity by combining with cutting logging data to finish the reservoir assessment. According to the method, the calculation of the logging porosity during drilling is realized, the real-time evaluation of reservoir during drilling is strengthened, steps are simple and easy to apply, and the logging porosity can be quantitatively calculated for carrying out the reservoir assessment.

Description

[0001] technical field [0002] The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a method for evaluating reservoirs by using micro-drilling data to calculate logging porosity while drilling. Background technique [0003] Reservoir evaluation is an important link in oil and gas exploration and development, and formation porosity is the main parameter for understanding reservoirs. In the past methods for obtaining formation porosity, logging and mud logging have adopted various methods, but all have their own limitations: [0004] 1. Using conventional and imaging logging data to interpret porosity is the most commonly used method, but it has hysteresis and belongs to post-drilling evaluation. [0005] 2. Porosity measurement by core is the most accurate method, but there are generally few core wells, and only some key wells are cored in key intervals. [0006] 3. Logging while drilling for horizontal wel...

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Problems solved by technology

[0006] 3. Logging while drilling for horizontal wells can realize reservoir evaluation while drilling, but it is expensive to purchase and rent foreign logging while drilling instruments, and most domestic logging while drilling parameters do not have porosity parameters

[0007] 4. The nuclear magnetic resonance logging applied in the field can analyze the porosity of core and cuttings samples, but the analysis time is long, and there are strict requirements on the particle size of cuttings samples

At present, drilling technologies such as PDC bit and gas drilling are widely used in the drilling process, resulting in fine particles of cuttings samples, which cannot meet the requirements of nuclear magnetic logging analysis.

[0008] 5. The comprehensive mud logging data can reflect the physical properties of the formation to a certain extent, but the qualitative judgment of the reservoir has been mainly based on experience, using the change trend of the meter-drilling data, and there is no quantitative calculation of the logging parameters using the mud logging parameters. Well Porosity Methods

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