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Method for real-time monitoring of pollution level of downhole formation water

A real-time monitoring and water pollution technology, applied in earth-moving drilling, wellbore/well components, etc., can solve problems such as inability to distinguish formation water and water-based mud, and inability to obtain formation water samples.

Active Publication Date: 2020-10-20
CHINA NAT OFFSHORE OIL CORP +1
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Problems solved by technology

Existing formation fluid sampling technology cannot distinguish formation water from water-based mud, and field engineers often rely on experience to judge the sampling timing based on the pumping time and parameter change curves, resulting in the inability to obtain pure formation water samples

Method used

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  • Method for real-time monitoring of pollution level of downhole formation water
  • Method for real-time monitoring of pollution level of downhole formation water
  • Method for real-time monitoring of pollution level of downhole formation water

Examples

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Effect test

Embodiment 1

[0074] This example takes a well in the Bohai Sea as an example to illustrate the downhole real-time monitoring method of the formation water pollution rate under the condition of water-based mud.

[0075] Step 1. Collect the absorbance OD of the water-based mud at the wavelength point of 1450nm wbm is 0.68;

[0076] Step 2, collect the curve of formation fluid absorbance OD (t), wherein t=(0-15000s), the curve of formation fluid absorbance OD (t) (wavelength point is 1450nm), such as figure 2 shown;

[0077] Step 3. Real-time calculation of formation water pollution degree in three stages of water-based mud invasion period, transition period and formation water stabilization period:

[0078] When t is at the time of 0-1820s, calculate ΔOD=OD(t)-OD(t-1) by formula (2); and bring ΔOD into formula (3) (n takes 9), the maximum obtained P(t) is 0.03, which is less than the threshold φ 1 , belongs to the early stage of pumping, water-based mud invades in large quantities, and...

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Abstract

The invention relates to a method for real-time monitoring of the pollution level of the downhole formation water. According to the method, real-time monitoring is performed on pollution of the downhole formation water based on near-infrared spectroscopy; the formation water and water-base mud can be effectively distinguished through the absorbance difference of the formation water and the water-based mud at a spectral water absorption peak; and respective proportions are worked out accurately and quantitatively in real time, thereby determining the pollution level of sampled fluid, and improving the sampling efficiency.

Description

technical field [0001] This paper relates to the field of petroleum exploration and pollution control technology, especially a method for downhole real-time monitoring of formation water pollution based on spectral analysis technology. Background technique [0002] During the sampling process of downhole formation water, a large amount of water-based mud filtrate is often invaded, which pollutes the formation fluid to a certain extent. The fluid property parameters obtained by sampling are the key information for subsequent oil and gas exploration and development, so how to obtain pure formation fluid is very important. Existing formation fluid sampling technology cannot distinguish formation water from water-based mud. Field engineers often rely on experience to judge the sampling timing based on the pumping time and parameter change curves, resulting in the inability to obtain pure formation water samples. Contents of the invention [0003] This application provides a m...

Claims

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Application Information

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IPC IPC(8): E21B49/08E21B49/00
CPCE21B49/08E21B49/005Y02A20/20
Inventor 杨玉卿孔笋张国强左有祥蔡建荣吴乐军冯永仁王显南褚晓冬沈阳
Owner CHINA NAT OFFSHORE OIL CORP
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