Device and method for evaluating capillary force in water injection process of oil reservoir

Abstract

The invention provides a device and method for evaluating the capillary force in water injection process of an oil reservoir. The device and the method can simulate the capillary force of a stratum inthe actual water injection process of the oil reservoir. A rubber sleeve is arranged in a cylinder of a core holder, the end of the rubber sleeve is sleeved with a tapered sleeve, a sealing press capis in threaded connection with the cylinder, and a stopper is fixed; the stopper is in threaded connection with a core plug, and the length of the core plug is adjusted; the inner end of the core plug is arranged in the rubber sleeve; a high-permeability metal isolation plate is arranged between the stopper and the core, and circulation channels are formed in the radius and tangential directionsof the high-permeability metal isolation plate; a sieve is arranged between the high-permeability metal isolation plate at the outlet end and the core plug, the outer end of the core plug is connectedwith a pipeline fixing connector, and an annular pressure connector is connected with the outer part of the cylinder. The method provides steps and processes for the specific operation of experimental equipment and how to obtain a curve about the capillary force and the saturation degree. The device and the method eliminate influences brought by semi-permeable isolation plates or semi-permeable membranes, meanwhile the influence of the liquid end effect is also weakened, and experimental data becomes more accurate and reliable.

Description

technical field [0001] The invention belongs to the technical field of laboratory experiments for oil and gas field development; in particular, it relates to a device and method for evaluating capillary force in the water injection process of oil reservoirs. Background technique [0002] Capillary force, or capillary pressure, refers to the additional pressure that exists on the curved interface of two immiscible fluids in the capillary. In the process of exploration and development of oil and gas fields, many properties of the reservoir, such as rock pore structure, rock storage performance, the relationship between oil-water saturation and the height of the oil-water transition zone, oil displacement efficiency, and wettability of reservoir rocks, etc. Determined using capillary force data. Therefore, accurate and effective acquisition of capillary force data is a prerequisite for oil and gas exploration and development. [0003] There are three main methods for measurin...

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Problems solved by technology

Mercury porosimetry has a fast test speed and a large measurement range, but it is quite different from the actual situation of the oil layer, pollutes the environment, and the core cannot be reused

Centrifugal test equipment and calculation are more complicated, the measurement range is limited, and the maximum pressure is only 1.4MPa

The semi-permeable barrier method is close to the conditions of the oil layer, and the measurement accuracy is high, but it will affect the fluid distribution in the core

When these methods are applied to determine the capillary force in the reservoir water injection process, there are several problems: (1) The fluid flow mode during the test process is different from the fluid flow mode under formation conditions, such as the most accurate semi-permeable diaphragm method One end enters the high-pressure fluid, and the other end seals the oil phase and cannot flow out of the core

Obviously, the semi-permeable partition will significantly affect the liquid distribution in the core, and cannot reflect the formation conditions and parameters more realistically; (2) These methods cannot test the capillary force under the reservoir conditions, so the measured capillary force and reservoir There are some differences in the real situation; (3) There are many equipments for testing the capillary force of reservoirs corresponding to various test methods, but none of them can truly reflect and accurately evaluate the capillary force in the process of water injection

Such as dynamic capillary force testing device, usually the test object is quartz sand or soil (i.e. sand-filled model), the pore permeability is very high, it is impossible to test the dynamic capillary force of formation or artificial low-permeability core

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