Device and method for measuring rock core-formation water-CO2 wettability change

Abstract

The invention provides a device and method for measuring rock core-formation water-CO2 wettability change in a CO2 oil displacement process, belonging to the field of testing methods in the field of gas field exploration and development. The method comprises the following steps: putting rock core into a high-temperature high-pressure kettle, adjusting to a proper position to ensure that formation water can be accurately dripped onto the rock core, dripping the formation water onto the rock core to form liquid drops, charging CO2 to adjust the pressure to a first pressure point, measuring the contact angle of the liquid drops under the first pressure point, charging CO2 until the liquid drops on the rock core completely disappear, adjusting the pressure to a second pressure point, repeating the process above until completing the measurement of the contact angles of the liquid drops under all pressure points, and finally, obtaining the wettability change law. The invention can be utilized to continuously measure the rock core-formation water-CO2 contact angle at certain formation temperature under different CO2 pressures, and simulates the change of rock wettability of the real oil reservoir in the CO2 displacement process.

Description

technical field [0001] The invention belongs to the field of testing methods used in the field of oil and gas field exploration and development, and specifically relates to a method for measuring rock core-formation water-CO 2 Apparatus and method for changing wettability. Background technique [0002] CO 2 Oil flooding is one of the most promising methods for enhanced oil recovery (EOR). When CO 2 After injection into the reservoir, many new phase boundaries will be formed, and the study of CO 2 The characteristics of the phase interface in the displacement process have important theoretical and practical significance. Among them, the change of rock wettability affects capillary pressure, relative permeability and fluid flow characteristics. [0003] At present, the wettability evaluation methods are divided into two categories: one is the Amott index method and the USBM index method, which can measure the average wettability of the core; the second is the contact angl...

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Problems solved by technology

[0011] In the existing literature, Daoyong Yang et al. used the contact angle method to measure CO 2 Core-formation water-CO during oil flooding 2 Wettability change (Daoyong Yang, Yongan Gu, Paitoon Tontiwachwuthikul. Wettability Determination of the Reservoir Brine-Reservoir Rock System with Dissolution of CO 2 at High Pressures and Elevated Temperatures.Energy & Fuels, 2008, 22, 504-509), the method is to first measure the core-formation water-CO at the first pressure point 2 For the contact angle of the second pressure point test, add 3-5mm 3 Formation water drops to the remaining liquid droplets at the first pressure point, although this method can roughly simulate the CO 2 Core-formation water-CO during oil flooding 2 Wettability changes, but does not overcome the impact of residual droplets from the previous pressure point on the accuracy of the next pressure point test

In the process of measuring the contact angle, the test of each pressure point must ensure that the surface of the core is smooth and flat, and no liquid droplets can remain, so the existing measurement methods are not accurate and there are large errors

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