A Well Test Interpretation Method for Calculation of Karst Cave Volume

A technology of well test interpretation and volume calculation, applied in the field of well test, can solve the problems of complex modeling process, poor adaptability and high cost of discrete fracture-vuggy network well test interpretation method

Active Publication Date: 2020-04-17
CHINA PETROLEUM & CHEM CORP
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  • Claims
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Problems solved by technology

[0007] However, in these methods, the cave volume obtained by the seismic fracture-cave carving method is the volume of the seismic anomaly body, not the volume of the geological anomaly body, and the conversion factor between the volume of the seismic anomaly body and the geological anomaly volume is difficult to determine; The calculation of the volume requires more accurate calculation of parameters such as the comprehensive compressibility coefficient, formation pressure, and water influx. However, it is difficult to determine these key parameters in fractured-vuggy reservoirs, resulting in low accuracy of calculation results.
Existing continuum well test interpretation methods have poor adaptability to large-scale fractured-cavity reservoirs, and cannot calculate key parameters such as cave volume in fractured-cavity reservoirs
The modeling process of discrete fracture-vuggy network well test interpretation method is complex and costly, which is not conducive to the widespread use in oilfields

Method used

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  • A Well Test Interpretation Method for Calculation of Karst Cave Volume
  • A Well Test Interpretation Method for Calculation of Karst Cave Volume
  • A Well Test Interpretation Method for Calculation of Karst Cave Volume

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0098] figure 1 The flow chart of the well test interpretation method for the calculation of the volume of the karst cave in embodiment 1 comprises the following steps:

[0099] Step 1. Establish a well test model according to the combination relationship of fractures, caves and wellbore in fractured-cavity reservoirs and reservoir parameters;

[0100] Step 2. According to the well test model, obtain the bottomhole pressure solution p in real space wD (t D );

[0101] Step 3. Using real space bottomhole pressure to solve p wD (t D ) are fitted with the measured bottomhole pressure data to obtain fracture permeability, wellbore storage coefficient, fracture length, fracture cross-sectional area and / or cave volume.

[0102] Among them, step 2 also includes:

[0103] Step 2.1: Solve the well test model by using Laplace transform to obtain the bottomhole pressure solution function in Laplace space

[0104] Step 2.2. Using the Stehfest numerical inversion technology, the b...

Embodiment 2

[0116] figure 2 It shows the combined relationship of fractures, caves and wellbore in the well-fracture-cavity well test model according to Example 2 of the present invention. The difference between the well test interpretation method in Embodiment 2 of the present invention and Embodiment 1 above is only in Step 1, and other calculation and solution methods are basically the same as Embodiment 1. In Example 2, the combined relationship of fractures, caves and wellbore includes: both the cave and the wellbore are one, and the bottom of the wellbore and the cave are connected through fractures, and the well test model thus established is called well-fracture-cavity well test model.

[0117] Among them, reservoir parameters include: p i Original formation pressure (MPa); p f Fracture pressure (MPa); p v Cave pressure (MPa); p w Bottom hole pressure (MPa); k f Fracture permeability (um 2 ); μ fluid viscosity (mPa.s); Fracture porosity (%); Karst cave porosity (%); C ...

Embodiment 3

[0153] Figure 5 It shows the combined relationship of fractures, caves and wellbore in the well-cavity-fracture-cavity well test model according to Example 3 of the present invention. The difference between the well test interpretation method of Embodiment 3 of the present invention and the above-mentioned Embodiment 1 lies in Step 1, and other calculation and solution methods are basically the same as Embodiment 1. In this embodiment 3, the combined relationship of fractures, karst caves and wellbores includes: having a first karst cave, a second karst cave, a fracture and a wellbore, the first and second karst caves are connected by fractures, and the bottom end of the wellbore is connected to the first or second karst cave. The two karst caves are connected, and the well test model thus established is called the well-cavity-fracture-cavity well test model.

[0154] Among them, reservoir parameters include: p i Original formation pressure (MPa); p f Fracture pressure (MP...

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Abstract

The present invention relates to a well test explanation method for cave volume calculation. The method comprises a first step of building a well test model according to a combination relationship of a crack, a cave and a wellbore of a seam type oil reservoir and measurement parameters of the crack, the cave and the wellbore; a second step of acquiring a real space bottomhole pressure solution according to the well test model; and a third step of fitting by using the real space bottomhole pressure solution and measured bottomhole pressure data so as to acquire parameters about crack permeability, a wellbore reservoir coefficient, a crack length, a crack cross-sectional area, and a cave volume. Through adoption of the well test explanation method for cave volume calculation, a corresponding well test explanation model is built according to different crack combination relationships, so that the volume of each cave is explained, further, the length and cross-sectional area of the crack or a seepage channel are obtained.

Description

technical field [0001] The invention belongs to the technical field of well testing, and in particular relates to a well testing interpretation method for calculating the volume of karst caves in carbonate fracture-cavity reservoirs. Background technique [0002] The reservoir space of fractured-vuggy carbonate reservoirs is dominated by dissolved caves. Currently, the commonly used methods for calculating the volume of dissolved caves include seismic fracture-cavity engraving method, material balance method and well testing method. [0003] Seismic fracture-cavity engraving method is based on the fine processing of seismic data, first extracts the attributes of the seismic energy body and carries out space carving, then calculates the volume of the energy body, and finally obtains the seismic anomaly body and geological anomaly body through statistics of a large number of forward modeling results The correction coefficient between , so as to obtain the real volume of the fr...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F30/20
CPCG06F30/20
Inventor 荣元帅杨敏潜欢欢巫波林加恩张晓
Owner CHINA PETROLEUM & CHEM CORP
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