Prediction of very thin (1–10 m) sandstone reservoirs is one of the ongoing strategies for reserve growth in the Songliao Basin, China. In this study we analyzed amplitude, instantaneous attributes, and continuity for their sensitivity and detectability in very thin sandstones developed in a Cretaceous, shallow, lacustrine delta. An amplitude-detectable limit of 1 m was determined by constructing an amplitude-thickness tuning curve using well and amplitude stratal slices. Seismic modeling and field-data attribute slices revealed that amplitude attributes are highly sensitive to 1- to 4-m-thick sandstones, whereas instantaneous-phase and -frequency attributes show less sensitivity in this thickness range. Continuity slices showed a result similar to that of phase and frequency slices. However, all attributes are useful in highlighting 4- to 10-m-thick sandstones. Display and interpretation of multiple attribute are recommended to reduce uncertainties in very thin bed imaging and mapping.
Thin and nonclinoformal deltaic sandstones are important reservoirs for future reserve growth in the Songliao Basin and elsewhere. In comparison with well-known, thick, deltaic systems that are associated with clinoformal seismic configurations, nonclinoformal deltaic systems have been less recognized and studied. In this study, we demonstrate that by recognizing high-order depositional sequences and analyzing seismic geomorphology using lithology-indicative seismic amplitude on stratal slices, seismic sedimentology can be an effective tool for studying shallow-water deltaic systems that are progradational but not seismically clinoformal.
Summary The structural pattern and tectono-sedimentary framework jointly contributed to the type of depositional systems and dispersal patterns, and further determined the type of reservoir sand bodies. In this study, the structural pattern and techtono-sedimentary framework for Ed3Member, Dongying Formation, QHD29-2 Block in Bohai Bay are proposed using sparse well data and 3-D seismic interpretation. The structural system of the study area is marked by sets of faults controlling the boundary of the Shijiutuo Uplift in the southern part of the study area. Fanshaped and lobate proximal fan deltas were rapidly deposited in the steep slope belt controlled by strong tectonic activities. Banded braided river deltas were deposited in the gentle slope belt with weakened tectonic activities after long-distance transportation. These sediment dispersal patterns serve as significant reference for the evaluation of hydrocarbon reservoirs in the study area.
Spectral recomposition splits the seismic spectrum into Ricker components. It provides a tool for imaging and mapping temporal bed thicknesses and geologic discontinuities. We propose a separable nonlinear least-squares estimation in spectral recomposition. Employing the Gauss-Newton method, separable nonlinear least-squares approach estimates fundamental signal parameters: peak frequencies and amplitudes.
The exploration targets have been turned to mid-deep reservoir after decades of exploration and development in Dagang oilfield in Qikou Sag, Bohai Bay Basin, thus higher requirements on clastic reservoir research were put forward and new technology was introduced, especially for the lithostratigraphic reservoir. In the study, Based on traditionally research such as core observation, rock slices identification, physical property analysis, etc., influencing factors of reservoir property, quantitative diagenetic research and comprehensive reservoir evaluation were carried out with quantitative mathematical statistics application. The result shows the evaluation method is suitable for the low porosity and permeability reservoir.