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A Method for Determining Safe Mud Density Window in Special Formation

A technology of mud density and determination method, which is applied in the field of oil drilling

Active Publication Date: 2020-06-30
CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Currently there is no method to identify this special formation and calculate the safe mud density window for this special formation

Method used

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  • A Method for Determining Safe Mud Density Window in Special Formation
  • A Method for Determining Safe Mud Density Window in Special Formation
  • A Method for Determining Safe Mud Density Window in Special Formation

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Embodiment Construction

[0050] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments. However, it should be understood that the accompanying drawings are provided only for better understanding of the present invention, and they should not be construed as limiting the present invention.

[0051] Such as Figure 5 As shown, a method for determining a special formation safe mud density window provided by the present invention comprises the following steps:

[0052] 1) According to the acoustic time difference, density, natural gamma ray data obtained from the logging of the target well and the indoor rock mechanics experiment, determine the rock mechanics parameters of the sedimentary rock formation, including the uniaxial compressive strength, cohesion and internal friction angle of the rock in the sedimentary rock formation;

[0053] In this embodiment, the indoor rock mechanics experiment for determining the rock mechanics parameters of...

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Abstract

The invention relates to a method for determining a safe mud density window of a special stratum. The method comprises the following steps of 1) determining rock mechanics parameters of a sedimentary rock stratum according to an acoustic time difference, density and natural gamma data obtained by target well logging and an indoor rock mechanics experiment; 2) according to natural gamma logging data and an actual measurement value of stratum bearing capacity at a drilling site, determining geomechanics parameters; 3) calculating a surrounding-well stress state by utilizing the geomechanics parameters; 4) judging whether the stratum has a collapse pressure upper limit or not; and 5) according to a symbolic-graphic combination principle, for three deformation and fracture forms, determining a collapse pressure lower limit, a fracture pressure and the collapse pressure upper limit, and obtaining the safe mud density window of the special stratum. By utilizing the method, the special stratum with the collapse pressure upper limit can be effectively and accurately identified, and the safe mud density window of the special stratum is determined.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling, in particular to a method for determining the safe mud density window of a special formation. Background technique [0002] In the field of petroleum industry, wellbore instability in the process of exploration and development of oil and gas fields seriously restricts the drilling speed and causes huge economic losses. According to the statistics of the drilling industry, the annual economic loss caused by the instability of the well wall in the world exceeds 100 million US dollars. In the actual drilling process, the formations that usually cause wellbore instability include: hard and brittle shale formations, bedding formations, fractured formations, steep and complex structures, and high-temperature and high-pressure formations. There are two main forms of wellbore instability and damage: wellbore collapse and wellbore rupture. The former is mainly due to the low mud density, whic...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F30/13
CPCG06F30/13
Inventor 袁俊亮周建良罗洪斌许亮斌殷志明郝希宁张玉亭高飞
Owner CHINA NATIONAL OFFSHORE OIL (CHINA) CO LTD