A METHOD FOR DETERMINING THE PINKOUT POINT OF SANDBODIES IN DELTA FRONT SHEET SAND RESERVOIRS

Abstract

The invention discloses a method for determining a tip vanishing point of a delta leading edge mat-shaped sand reservoir sand body. The method specifically comprises the following steps: drawing deltaside edge envelope lines on the sedimentary microfacies diagram by using two straight lines and determining an envelope line intersection point A; drawing a delta leading edge underwater shunting river channel tail end envelope line according to the curve; as for drilled mat-shaped sand well points, calculating the data that the thickness h of the mat-shaped sand body of the W well is equal to the distance L between the well point and the underwater shunting river channel tail end envelope line by using the ray AW as the delta extension direction at the W well; counting the data of all drilled mat-shaped sand well points and making an h-L cross plot; and reading the intercept m of the fitting straight line on the L axis according to the data points in the straight line fitting cross plot,and m is the distance between the mat-shaped sand tip vanishing point and the shunting river channel tail end envelope line in the delta extension direction so that the position of the mat-shaped sand tip vanishing point encountered by well point drilling is determined. The invention provides a simple, reasonable and effective method for determining the tip vanishing point of the delta leading edge mat-shaped sand body.

Description

technical field [0001] The invention relates to the technical field of exploration and development of oil and gas reservoirs, in particular to a method for determining the sandstone pinch-out point of a delta front sheet sand reservoir. Background technique [0002] Delta front sedimentary reservoir is an important oil and gas reservoir type, and one of the key reservoir types in oil and gas exploration and development research. In delta front deposits, sedimentary microfacies generally developed as good reservoirs include subaqueous distributary channels, mouth bars and sheet sands. Compared with underwater distributary channels and mouth bars, the sheet sand microfacies sedimentary sand body has the characteristics of small thickness and large distribution area, and the sheet sand sedimentary sand body gradually thins along the direction of delta extension until finally pinches out. Although the sheet sand body is small in thickness, the sandstone is well sorted, the rese...

AI Technical Summary

Problems solved by technology

For the second type of method, due to the limitation of the vertical resolution of seismic data, it is difficult to achieve accurate resolution for sand bodies whose thickness is less than a quarter of the seismic wavelength.

The sheet sand deposits gradually change in thickness along the flow direction of the main channel until they are pinched out, and the sheet sands with a thickness less than a quarter of the wavelength will have a wide distribution range, which makes the pinch-out point of the sheet sand determined by the second method very inaccurate

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