A new method for determining the wettability of tight rocks

Abstract

The exploration and development of unconventional oil-gas reservoirs, especially the dense gas-oil reservoir, has become a bright spot of the oil exploration and development in recent years and a mainbattlefield of the future oil exploration and development. The wettability is one of important parameters for knowing dense oil-gas reservoir characteristics, and an operation of effectively determining the rock wettability has important significance for researching recovery percent of the oil reservoir, an oil-water ratio after water channeling, recovery ratio improvement and residual oil saturation. The invention discloses a new method for dense rock wettability determination, the disadvantages that the traditional self-absorption metering is inaccurate and nuclear magnetic resonance oil-water signals are hard to distinguish are overcome, a nuclear magnetic signal of the water is shielded by effectively utilizing manganese chloride, the self-water-absorbing oil discharge amount, water-driving oil amount, self-oil-absorbing water discharge amount and oil-driving water amount are accurately acquired by combining T2 spectral curve of the rock and weighing and weight change characteristics thereof, and the effective determination of the dense rock wettability is realized. The new method disclosed by the invention has the advantages of being small in current personal factor influence, high in data reliability, and simple and convenient.

Description

technical field [0001] The invention relates to a new method for determining the wettability of tight rock, which belongs to the technical field of oil and gas exploration. Background technique [0002] The exploration and development of unconventional oil and gas and tight oil and gas have become the highlights of oil exploration and development in recent years. Wettability is one of the important parameters to understand the characteristics of tight oil and gas reservoirs. Effective determination of rock wettability is important for the study of reservoir recovery, oil-water ratio after water channeling, enhanced recovery and remaining oil saturation. significance. Therefore, since the 1930s, many scholars have carried out a large number of studies on the wettability of reservoirs. Based on the analysis of the interaction relationship between water-oil-rock systems, a variety of methods for evaluating wettability have been formed. The following methods are often used in ...

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Problems solved by technology

[0009] (1) The rock porosity of tight reservoirs is small, and the pore space is smaller than that of conventional reservoirs. Traditional metering devices cannot accurately measure the water production and oil production of rock samples.

[0010] (2) The pore-throat radius of tight reservoir rocks is small, and a large centrifugal force is required in the centrifugation process. Therefore, when using the USBM method and the Amott-USBM combination method, a centrifuge with a relatively high speed is required, and the traditional centrifuge device cannot meet this requirement. high speed

[0011] (3) When judging wettability by the self-suction method, during the process of self-suction oil discharge and self-suction oil drainage, the discharged liquid is easily adsorbed on the wall of the self-suction pipe, so that the final reading on the self-suction pipe differs greatly from the actual liquid output , causing the interpretation results to be inconsistent with the actual

[0012] (4) Although the two-dimensional nuclear magnetic resonance method can accurately identify oil-water signals, its principle and calculation process are very cumbersome and require high equipment

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