Stratigraphic Analysis of Diplogs: ABSTRACT

Abstract

Recently, the diplog has been used to estimate stratigraphic conditions of the formations penetrated by a borehole. In particular, the diplog frequently can be utilized to predict the trend, direction of thickening, and movement of depositing currents in channel-and barrier-bar sandstones. Because of compaction and bifurcation, channel sands tend to be more complex and difficult to interpret using a diplog. However, barrier-bar sands commonly can be interpreted correctly from the diplog. Many thick sequences of fluvial sands do not exhibit channel-dip patterns. In some problems, the use of statistical analysis is useful. In many instances, the determination of the type of sand from a diplog in fluvial sequences will be difficult. Barrier-bar sands exhibit several different types of crossbedding depending on the relative importance of tides, longshore currents, and onshore winds in forming and modifying these deposits. The present interpretational techniques for this type of deposit use differential compaction of the overlying shales as a key to the analysis. The general interpretation of diplogs for stratigraphic information requires the use of statistical plots. The polar coordinate (modified Schmidt) and azimuth frequency plots especially are useful in the analysis of certain stratigraphic anomalies. End_of_Article - Last_Page 1832------------