Method for determining drilling fluid density in salt-gypsum layer deflection

A technology of drilling fluid density and determination method, applied in chemical instruments and methods, earthwork drilling, flushing wellbore, etc., can solve problems such as limited formation pressure bearing capacity, easy leakage of lost circulation, restricting downhole directional instruments, etc., to prevent The effect of wellbore shrinkage and prevention of downhole complications

Active Publication Date: 2011-07-20
PETROCHINA CO LTD
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Problems solved by technology

In the process of oil drilling, sub-salt horizontal wells drill deep salt layers and there are weak formations between the salts, the formation pressure bearing capacity is limited, and lost circulation is prone to occur; the perfo

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  • Method for determining drilling fluid density in salt-gypsum layer deflection
  • Method for determining drilling fluid density in salt-gypsum layer deflection
  • Method for determining drilling fluid density in salt-gypsum layer deflection

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[0021] The technical solution of the present invention will be described in detail below with reference to the drawings and embodiments.

[0022] The embodiment of the present invention provides a method for determining the density of a salt-gypsum layer deflection drilling fluid, which is applied to a salt layer of a certain well in a certain block with a depth of 3350 meters, and specifically includes the following steps:

[0023] (1) For a composite salt-gypsum layer of a certain structure, the wax-sealed salt rock cores obtained by drilling and coring were processed with experimental samples to obtain standard cores (diameter 25.5mm, length 50mm cylinder, or diameter 38mm, length 72mm cylinder) 4 groups total 16 pieces (if possible, more groups are possible), that is, the angles of the same X axis are 0°, 45°, and 90° respectively; the angles of the same Z axis are 0°, a total of 4 blocks are 1 group;

[0024] (2) Perform creep tests on the obtained standard cores on a rock cree...

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Abstract

The invention relates to a drilling technology in the field of petroleum exploration and development, in particular to a method for determining drilling fluid density in salt-gypsum layer deflection. The method for determining drilling fluid density in salt-gypsum layer deflection comprises the following steps of: (1) establishing a salt-gypsum layer creep model under the variable-curvature and variable-azimuth conditions; (2) according to the salt-gypsum layer creep model, establishing a salt-gypsum layer borehole wall deformation model under the conditions of drilling fluid density, borehole curvature and borehole azimuth; (3) establishing a relationship chart of the drilling fluid density, borehole curvature and borehole azimuth; and (4) according to the relationship chart established in the step (3), determining the reasonable drilling fluid density. By using the method provided by the invention, the appropriate drilling fluid density, deflection azimuth and deflection curvature can be preferably selected, thereby reducing the drilling fluid density to satisfy the minimum burst pressure of the stratum, effectively preventing borehole undergauge and avoiding complex downhole circumstances.

Description

technical field [0001] The invention relates to drilling technology in the field of petroleum exploration and development, in particular to a method for determining the density of drilling fluid for deflection in salt-gypsum layers. Background technique [0002] The formation of deep oil and gas reservoirs in many petroleum-bearing basins in the world is related to gypsum-salt layers, and the number of oil and gas reservoirs developed under gypsum-salt layers is relatively large, which will be the focus of deep oil and gas exploration in the future. In the process of oil drilling, sub-salt horizontal wells drill deep salt layers and there are weak formations between the salts, the formation pressure bearing capacity is limited, and lost circulation is prone to occur; the performance of high-density drilling fluid in the deflection section seriously restricts the effectiveness of downhole directional tools At the same time, the wellbore trajectory also has a great influence o...

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Application Information

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IPC IPC(8): E21B47/00E21B49/00E21B21/00C09K8/04
Inventor 滕学清李宁陈勉金衍文志明
Owner PETROCHINA CO LTD
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