Oil-rich and loose sandstone standard rock core column freezing coring method and coring clamp

Abstract

The invention relates to an oil-rich and loose sandstone standard rock core column freezing coring method and a coring clamp. The method comprises the steps that a full-diameter rock core of an oil-rich and loose sandstone is drilled on site, and the full-diameter rock core is frozen and solidified after sampling and sealing; the frozen full-diameter rock core is sectioned into small-sized rock samples at low temperature, and small-sized rock samples are subjected to deep freezing treatment; the small-sized rock samples subjected to deep freezing are fixed, the outer walls of the small-sized rock samples are drilled through a drilling machine, oil-rich and loose sandstone standard rock core columns are formed, and the oil-rich and loose sandstone standard rock core columns are subjected topressure control, packed and stored. According to the method, sealing is conducted after sampling in the sampling process, the frozen full-diameter rock cores are broken into parts, the small samplesare subjected to deep freezing, in combination with the novel coring clamp, the oil-rich and loose sandstone standard rock core columns can be successfully drilled through the method, the demands ofvarious analysis and testing of the oil-rich and loose sandstones are met, the integrity and comprehensiveness of various test data of the oil-rich and loose sandstones are guaranteed, and powerful guarantees for the adjustment of oilfield development programs and potential tapping of measures in high water content stage are provided.

Description

technical field [0001] The invention relates to the technical field of geological exploration, in particular to a method for freezing and coring a standard core column of oil-rich loose sandstone and a coring fixture. Background technique [0002] At present, most of the domestic water injection development oilfields have entered the stage of high water cut. Development plan adjustment and measures to tap potential are the main tasks of reservoir management in the middle and later stages of oilfield development, and the analysis and testing of reservoirs and fluids are particularly important. Standard core columns (standard core columns refer to core columns with a diameter of 1 inch and 1.5 inches) can be used in various geological experiments, usually for porosity and permeability, mercury injection, five sensitivity, phase permeability, displacement, stress sensitivity, etc. A variety of experimental tests, from the original sample of the collected rock to the standard co...

AI Technical Summary

Problems solved by technology

After being refrigerated at minus 18 degrees Celsius, and then frozen with liquid nitrogen for 4 hours, the water can be frozen very solidly, but the oil and gas cannot be frozen to the strength of ice, so the oiliness greatly reduces the effect of freezing and reduces the quality of the entire rock sample. the sturdiness of

In addition, after long-term water flooding, the rock samples are poorly cemented and in a loose state, which further increases the difficulty of firming the samples.

[0006] (2) Oil-rich unconsolidated sandstone has relatively high humidity due to the oil contained in it and the retained water. During the drilling and cutting process of the drill bit, the viscosity of the drilled rock debris increases under the action of oil and water, and it is not easy to remove Blowing out of the drill bit causes the drill bit to be blocked, and the congested debris increases the friction between the drill bit and the core column. When the drill bit is running at high speed, this friction force becomes a torsion force acting on the core column. The existence of this torsion makes the core column very easy to be twisted off during the drilling process, resulting in the failure of coring

[0007] (3) When the drill bit drills the core column, the friction between the high-speed rotating drill bit and the core generates high heat, which dissolves the oil and water in the rock sample, and the dissolved oil and water increase the viscosity of the rock sample debris, which is not conducive to drilling and cutting. The peeling off of the debris caused congestion of the debris inside and outside the drill bit. The congested debris isolated the heat from the drill bit and also isolated the cooling of the working part of the drill bit by liquid nitrogen, so that the heat generated by friction could not be cooled quickly. Acting on the core column, the oil and water inside the rock sample are continuously melted, the support force between the loose sandstone particles is lost, softened and deformed, and the muddy phenomenon is more serious, the overall structure of the rock sample is destroyed, the rock sample is broken, and it is impossible to drill. Take standard core column

[0008] (4) The rock sample should be fixed and clamped on the drilling frame with a clamp when drilling the core. This kind of clamp has a very large extrusion force on the rock sample, which is also a kind of damage to the rock sample with insufficient solidification strength. Force, coupled with the vibration generated when the drill bit runs at high speed, will inevitably act on the rock sample. Under the pinch of this internal and external force, the rock sample that is not tightly cemented itself will be easily shattered, and the required drill bit cannot be drilled. core column

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