The Carbonate Platform Model and Reservoirs’ Origins of the Callovian-Oxfordian Stage in the Amu Darya Basin, Turkmenistan

Abstract

Abstract:The Calloviane-Oxfordian carbonates in the northeastern Amu Darya Basin of southeastern Turkmenistan are composed of medium-to thick-bedded, mostly grainy limestones with various skeletal (bivalves, brachiopods, echinoderms, foraminifera, corals, and sponge) and non-skeletal grains (intraclasts, ooids and peloids). Two facies zones, six standard facies belts and some microfacies types were recognized, and sedimentary model "carbonate ramp-rimmed platform" was proposed and established that can be compared with the classical carbonate sedimentary models. In this model, favorable reservoirs not only developed in the intraplatform shoal of open platform, or reef and shoal on the platform margin, but also in the patch reefs, shoal and mound facies on the upper slope. The reservoir's pore space is dominated by intergranular and intragranular pores and fissure-pore reservoirs exist with medium porosity and medium to low permeability. Sedimentary facies and diagenetic dissolution are the key controlling factors for the development of high-quality reservoirs.

Analysis on ecological characteristics of Mississippian coral reefs in Langping, Guangxi

“…The fragments of carbonate base broken by storm in the clastic beach haven’t been observed. The study area is considered to be gentle-slope open platform 27 , 28 based on sedimentary characteristics. It suggests that the study area was far away from the margin of steep-slope platform that directly affected by waves, and more consistent with less energetic internal environments of gentle-slope platform.…”

“…The inhabitants on the beach could not resist strong waves. These rises were therefore known as reef-beach complexes and could only persist where waves and currents were mild 28 . They were essentially different from the framework coral reefs which developed on steep-slope platform margin that reflected changed hydrodynamic conditions, nutrient sources, reef sizes, and growth rates.…”

Types and Distribution Characteristics of Callovian-Oxfordian Reservoir on the Right Bank of Amu Darya River in Turkmenistan

“…The Amu Darya Basin in Turkmenistan is an important oil-gas-bearing basin in the world [1][2][3][4], in which the middle-upper Jurassic Callovian-Oxfordian limestone is a key oil-gas-bearing reservoir [5,6], with proven gas reserves of about 22 trillion cubic meters and remaining gas resources of about 20 trillion cubic meters. Thus, how to effectively explore and develop these oil and gas resources has become a crucial target of oil geologists worldwide.…”

Carbonates

“…Finally, the geological background cannot be disregarded. The paper by Xu and colleagues [9] presents a geological work, included in this collection due to the careful consideration of the mechanisms of dissolution and recrystallization occurring at the mineral surfaces/interfaces associated with the porosity, linking the nano-and microscale studies with macroscale (geological) studies.…”