Donghe Sandstone Research Articles

High Resolution Sequence Stratigraphy Characteristics and Distribution of Donghe Sandstone in Qunkuqiake Region in Tarim Basin

Qunkuqiake Region is an important exploration block in Tarim Basin. Donghe Sandstone is the main oil and gas target stratum. In order to reveal the rules of migration of the sand body and predict the favorable reservoir accurately, two high-frequency cycles are identified in Donghe Sandstone each of which consists of rising hemicycle and descending hemicycle, the sedimentary characteristics are analysed within the sequence stratigraphic framework and the barrier bar subfacies are identified beginning with the sedimentary characteristics of glutenite through the study of drilling stratigraphic section using drilling data, well logging data and cores data. This paper has disclosed the transition of the sedimentary environment from barrier-free coast system to barrier coast system during the period from rising hemicycle to descending hemicycle and the planar distribution of sedimentary facies of different high frequency sequence of Donghe Sandstone.

Feature, origin and distribution of calcareous interlayers: A case of Carboniferous Donghe sandstone in Hade Oil Field, Tarim Basin, NW China

The petrologic characteristics, well-logging, genetic models and distribution patterns of calcareous inter-layers in Carboniferous Donghe sandstone, Hade Oil Field were investigated systematically by using data such as outcrop, cores, thin sections, stable carbon and oxygen isotopic compositions, conventional logging curves, and dip logging curves. Calcareous inter-layers in the study area are made up of calcareous fine sandstone or calcareous siltstone of high compositional and textural maturity, in which calcareous components include calcite, ferro-calcite, dolomite, ferro-dolomite and anhydrate. Although the calcareous inter-layers are usually thin, they can be identified by combining conventional logging curves with dip logging curves. Three genetic models of calcareous inter-layers are identified, including shallow burial fresh water, evaporation and deep burial. According to the development of sedimentary facies, it is inferred that calcareous interlayers are well-developed in shore face and backshore sandstones, and likely to join together and show continuity between wells; based on features of high-resolution sequence stratigraphy, it is concluded calcareous inter-layers in Donghe sandstone have five types of occurrence: “upper calcareous-lower argillaceous” type, “upper argillaceous-lower calcareous” type, “calcareous-argillaceous-calcareous” type, purely calcareous type and “calcareous-argillaceous complex” type.

Petrological Characteristics of Donghe Sandstone Reservoir in HD4 Oil Field

Based on comprehensive study of the thin section identification, X-ray diffraction analysis, scanning electron microscopy, the heavy mineral analysis data, the lithology of Donghe sandstone reservoir in HD4 oil field, Tarim Basin, is mainly lithic feldspar-porphyry sandstone, fill in the gap content with calcite, shale and anhydrite primarily. The area that is far away from the source, and the original rock are sedimentary metamorphic rocks. Pore types are primary interparticle pore, inside particles dissolve pore and fissure pore. Clay mineral are mixed by Chlorite, illite and kaolinite.

Performance evaluation for littoral-facies clastic reservoir architecture

Taking the littoral-facies clastic reservoir of Donghe sandstone in HD4 oil field, Tarim Basin, NW China as an example, this paper analyzes the effect of different reservoir architecture pattern on oil well production performance. There are three types of reservoir architecture patterns in the target layers of the study area, parallel, groove and oblique. The dynamic response characteristics of different reservoir architecture patterns were discussed by establishing the conceptual model of different reservoir architecture patterns, in conjunction with numerical reservoir simulation results and actual production performance of the study area. Based on the numerical simulation, together with analysis of geologic factors and performance evaluation, a performance evaluation method for clastic reservoir architecture of littoral facies was put forward, in turn, the distribution scopes of different reservoir architecture patterns in the study area were identified by this method. The research results show that the parallel reservoir architecture only affects oil well production in vertical direction, the oblique reservoir architecture has the strongest effect on oil well production performance, reflected in both vertical and lateral direction, the effect of groove reservoir architecture on oil well production is mainly in vertical direction, relatively weak in lateral direction. Different adjustment measures should be adopted for the distribution areas of different reservoir architecture patterns.

Calcite cements in burrows and their influence on reservoir property of the Donghe sandstone, Tarim Basin, China

Abundant burrows of Skolithos linearis, Palaeophycus tubularis, and Taenidium barretti are preserved in the Upper Devonian Donghe sandstone of Tarim basin, China. They are commonly highlighted in core by the color of the burrow fill in contrast to the surrounding matrix and have dif- ferent textures and fabrics from the matrix. There are three kinds of calcite cements in burrows, microcrystalline-crystalline calcite cement, mosaic calcite cement, and ferroan calcite cement. Microcrystalline-crystalline calcite cement is widely distributed in the lower part of the Donghe sand- stone, but it is rare in burrows filling. It displays a globule structure under burial cementation and sel- dom replaces the quartz grains in shallow burial depth stage. Mosaiccalcite cement is widespread in the Donghe sansdtone reservoir of North Tarim basin. It shows chrysoidine, orange and bright orange lu- minescence, and intensely replaces the quartz grains, forming in early diagenetic and shallow burial depth stage. Ferroan calcite is asymmetrically distributed in the Donghe sandstone reservoir of Central Tarim basin. It fills the remanent pores in the shape of mosaic and replaces the quartz grains, matrix, and early calcite cement, forming in late diagenetic and deep burial depth stage. The burrows filled with white calcite cements have low oil saturation or may be oil-stained. In contrast, there is high oil saturation in the sandstone reservoir where the bioturbation is sparse or not present. With increased bioturbation, the porosity, permeability, and oil saturation decrease; thus, bioturbation intensity and reservoir property appear to be negatively correlated.

Application of Pre-Stack Inversion to a Complex Reservoir Prediction: a Case Study in LG34 Area, Tarim Basin

The Donghe Sandstone formation (DS fm. for simplicity) presents an excellent thin condensate gas reservoir in LG34 well area, Tarim Basin. Unfortunately, drilling results show that the reservoir is thin, deeply buried (below 5000m) and mix lithologies. Pre-stack inversion and fluid identification is implemented in this area. The feasibility and validity of pre-stack inversion for this kind of reservoir is tested, since that application of pre-stack inversion in this area is for the first time. A new rock physics model is used for estimating rock velocities and elastic attributes, and cross-plots of Poisson's ratio (σ) again LambdaRho (λρ) is found to be more favorable for lithofacies identification. Then, pre-stack inversion which uses seismic data with careful amplitude processing is performed to predict the reservoir. The inversion results agree and tie with most wells, suggesting that the pre-stack inversion is viable process for this complex lithological reservoir prediction in the area.

Unsteady reservoir in Hadson Oilfield, Tarim Basin

Abstract Unsteady reservoir, characterized by oblique oil-water contact or an upside-down relation between gas-oil-water in interconnected reservoirs, refers to a kind of hydrocarbon reservoir still in the process of hydrocarbon charge or adjustment in which a uniform oil-water contact does not come into being and there is a dynamic nonbalance between gas, oil, and water. This article takes Donghe sandstone in Hadson Oilfield in Tarim Basin as an example and makes the analyses on the origin of oblique oil-water contact, showing that the Donghe sandstone is undergoing hydrocarbon adjustment with obviously unsteady hydrocarbon concentration, and neotectonic movement is the major cause of the oblique oil-water contact. We put forward the concept of unsteady reservoir based on physical modeling, which has been applied in the hydrocarbon exploration and development of Hadson Oilfield. After successive exploration and development for nearly 3 years, the Hadson Oilfield has gained increasing reserves in place and become the first large-scale marine sandstone oilfield in China, with the proved reserves exceeding a hundred million tons.

Frasnian-Famennian boundary events in Tarim Basin, Xinjiang, Northwest China

In the Tarim Basin (in the Xinjiang Uygur Autonomous Region, Northwest China), the Frasnian-Famennian (F-F) boundary and boundary events within the Upper Devonian are revealed by applying the chemo-biostratigraphic method. At Bachu County, Tarim Basin, the F-F boundary is placed near the base of the Middle Member of the Bachu Formation. This result indicates that the important oil-reservoir bed, Donghe Sandstone, has an age no later than the Frasnian. Nickel anomalies and gypsum beds in the F-F boundary beds might have an origin of rifting-hydrothermal process.

The Devonian–Carboniferous Boundary and Events at Bachu, Xinjiang, Northwestern China

The Devonian-Carboniferous boundary in Bachu County of the Xinjiang Autonomous Region is identified by chemo-biostratigraphic methods and placed near the base of the Upper Member of the Bachu Formation. The important oil-reservoir bed of the Tarim Basin, the Donghe Sandstone, should not be attributed to the Early Carboniferous, because it has an age no later than the Frasnian. Gypsum beds and a Ni-Cr-Cu-Ti anomaly in the Devonian-Carboniferous boundary beds may have had an origin in a rifting-volcanic-hydrothermal process.

A Study of Sedimentary Environment and Reservoir Quality of the Carboniferous Donghe Sandstone in the Tarim Basin

Abstract Very thick, fine–grained quartzose sandstone of the Lower Carboniferous (called the Donghe sandstone) was discovered in Donghe–1 well in the Tarim basin. Highly–productive commercial oil and gas flows were obtained when a well completion test was conducted. This important discovery proved that the quartzose sandstone is a prospecting target with good prospects. After that, other two paying oil and gas flows were found in the Lower Carboniferous in the Tazhong–4 and Tazhong–10 structures (Tazhong means central Tarim), equivalent to the Donghe sandstone. The Tazhong–4 structural oil field is the biggest oil field ever discovered. Therefore it is of guiding importance in oil and gas exploration to deepen the study of sedimentary and reservoir features and the sedimentary environment of the Donghe sandstone and to build a sedimentary model in order to understand the reservoir distribution pattern.