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Strong-inhibition efficient shielding temporary plugging protection reservoir drilling fluid and preparation method thereof

A shielding temporary plugging agent and strong inhibition technology, applied in chemical instruments and methods, drilling compositions, etc., can solve the problem of not well inhibiting shale hydration expansion, affecting oilfield development efficiency, downhole irregularities, etc. problem, to achieve the effect of high-efficiency shielding and temporary blocking, strong anti-collapse inhibition ability, and easy performance

Inactive Publication Date: 2014-03-26
CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, none of the drilling fluids in the prior art can achieve the above-mentioned purpose, and the shielding temporary plugging agent in the prior art is not suitable for the low-porosity and low-permeability micro-fracture reservoirs in the Longdong area of ​​Changqing Oilfield due to its relatively large particle size. Due to the poor inhibition of the existing mud shale, the hydration expansion of the mud shale cannot be well inhibited, resulting in downhole irregularities or instability of the well wall and even downhole accidents, which affect normal drilling or oilfield development efficiency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The natural fractures developed in the reservoir play an important role in the migration and accumulation of oil and gas. The existence of fractures greatly increases the reservoir permeability, and becomes the material basis for successful exploration and economic development of low permeability and oil and gas reservoirs.

[0026] According to the observation of casting thin sections and scanning electron microscope photos, the micro-cracks in the Yanchang Formation reservoirs in the study area are of various shapes, widely developed in rock clastic aggregates, and micro-cracks are also developed in mineral clastics and interstitials . The length of the micro-cracks varies, in the range of 10-50 μm, the average crack length is 21.74 μm; the opening degree is between 1-10 μm, mostly in the range of 2-4 μm, and the average opening degree is 2.7 μm.

[0027] After the transformation of dissolution, some cracks are not only widened by dissolution, but some feldspars near...

Embodiment 2

[0034] Strong inhibition and high efficiency shielding temporary plugging protection reservoir drilling fluid protection effect evaluation

[0035] According to the characteristics of the reservoir and raw pulp in the work area, the effects of two different modified pulps on protecting the reservoir were evaluated respectively. The formulas of these two modified slurries are as follows: 1# drilling and completion fluid + 2% temporary plugging agent + 1% filler particles, 1# drilling and completion fluid + 2% temporary plugging agent + 1% filler particles + 1% deformed particles . The experimental instrument is CWCTAcid-I high temperature and high pressure acid dissolution plugging evaluation instrument. The experimental fluids are two kinds of modified slurry and the formation water of Yanchang Formation. The experimental rock samples are artificially fractured sandstone samples. Experimental conditions: drilling and completion fluid temperature T=75°C, pressure difference △P...

Embodiment 3

[0042] Evaluation of Inhibition and Anti-slump Property of Drilling Fluid

[0043] Experiment of recovery rate of cuttings after hot rolling (Table 1)

[0044] Table 1 Inhibition evaluation of cuttings

[0045] Numbering sample Primary recovery rate (%) Secondary recovery rate (%) 1 Clear water + cuttings 26.50 23.58 2 Puree+cuttings 19.68 18.12 3 Modified 1# mud + cuttings 95.04 75.28 4 Modified 2# mud + cuttings 94.22 82.6

[0046] It can be seen from the table that the primary recovery rate and secondary recovery rate of raw pulp are very low, which are lower than the primary and secondary recovery rates of clear water. Experiments on the recovery rate after adding 7% inorganic inhibitor and 5% organic inhibitor to the mud after adding temporary plugging agent respectively, it can be seen that the modified 2# mud shows good inhibition to cuttings , both primary and secondary recoveries are high.

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Abstract

The invention discloses strong-inhibition efficient shielding temporary plugging protection reservoir drilling fluid. The drilling fluid comprises the following components by weight percent: 2-5% of new shielding temporary plugging agent, 3-7% of inorganic salt inhibitor, 3-7% of organic inhibitor, 0.3-0.5% of low-viscosity polyanionic cellulose, 0.1-0.3% of high-viscosity polyanionic cellulose, 0.1-0.3% of viscosity enhancer, 0-3% of barite and the balance water, wherein NaOH is added to adjust the pH value to 9-10. The drilling fluid is used to effectively and temporarily plug the micro-cracks of the reservoir, has efficient plugging property and shallow layer property and ensures that some solid particles of the later drilling fluid can not enter the reservoir, thus the reservoir can be protected; and the drilling fluid has very good inhibitory property, and can balance the formation pressure and have the function of stabilizing the well wall.

Description

technical field [0001] The invention relates to a drilling fluid with strong inhibition and high-efficiency shielding and temporary plugging protection for reservoirs and a preparation method thereof, which can effectively block the protection reservoirs of micro-fracture reservoirs. Background technique [0002] In the prior art, the reservoir has poor physical properties, low permeability, and poor connectivity of pore throats. It belongs to low-porosity and low-permeability reservoirs, and has the nature of natural micro-fractures. The development of micro-fractures is the result of oil and gas seepage. main channel. Due to the strong sensitivity of the reservoir, during the drilling process, the incompatibility of the drilling fluid and the formation water will often cause precipitation, thereby blocking the pores; in addition, some insoluble and non-drainable solid particles in the drilling fluid will also The clogging of the fractures, and the drilling fluid and the r...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K8/03C09K8/506
Inventor 贾俊苏欢巨满成金祥哲曲波马祥林李波张建斌黎金明李博
Owner CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD
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