What Are Clastic Rocks?

Rock formed by the handling, deposition, compaction, and cementation of minerals and rock fragments produced by mechanical weathering of the host rock. In addition to the debris particles, its components are also heterogeneous and cement. According to the size (granularity) of the clastic particles, it can be divided into conglomerates and breccias, sandstones, and siltstones. ^[1]

It is the product of the mother rock's mechanical crushing.

Can be divided by material source

Terrestrial clastic rocks are mainly composed of particles, heterogeneous bases, voids and cementitious materials:

Granules, also called debris, can be divided into

Clastic mineral composition

With the sharp increase in energy demand, the proportion of heterogeneous clastic rock reservoirs with low porosity, low permeability, and compactness is increasing, which has drawn great attention from scholars and oil companies at home and abroad. The pore structure of heterogeneous clastic reservoirs is closely related to physical properties, seepage and electrical properties, and is an important factor affecting reservoir quality and fluid properties. At home and abroad, there is a lack of systematic quantitative evaluation techniques for the pore structure of heterogeneous clastic rock reservoirs. Saturation calculations, fluid properties, identification of oil-water interfaces, and productivity evaluation also lack effective treatment methods for logging in heterogeneous clastic rock reservoirs. Fine evaluation brings great difficulties and restricts the success rate of exploration and development of this type of oil and gas reservoirs.

The development of numerical simulations in petrophysics, experimental testing and well logging has enriched people's understanding of reservoir properties. Response characteristics at different scales can be obtained through multi-disciplinary and multi-information analysis. For heterogeneous clastic rocks, multi-information fusion technology is used to analyze the pore structure and establish saturation models and fluid identification standards to achieve comprehensive evaluation of qualitative and quantitative reservoirs, thereby improving the interpretation coincidence rate. Focus. ^[4]

The research status of clastic rocks in China includes the following aspects: research on the thermal degradation mechanism of organic matter and secondary pores; chemical heat (calibration of mechanical equilibrium theory for the thermodynamic conditions and conditions of diagenetic reactions; fluid, temperature, pressure, basin settlement Shi et al. Highly integrated petroleum geology analysis; tight integration of diagenesis and modern stratigraphy and sedimentology research. ^[5]

In addition, a lot of work has been carried out by domestic and foreign scholars on logging evaluation of heterogeneous clastic rock reservoirs, and great progress has been made in pore structure, macro-logging response, and petrophysical numerical simulation, which promotes heterogeneous clastic Logging evaluation of rock reservoirs, but there are still areas that need to be further deepened:

1. The organic combination of microscopic pore structure and well logging response enables calculation of reservoir parameters and evaluation of pore structure under formation conditions.

2. Quantitatively study the influence of microscopic pore structure on rock physical properties and establish a reservoir parameter model based on the pore structure.

3. The micro-pore structure parameters and mud, stratum water and other attributes are integrated into the rock electrical parameters to establish a universal saturation model.

4. Fully apply modern mathematical algorithms such as nuclear mapping, support vector machines, and wavelet analysis to optimize modeling and improve logging evaluation accuracy. ^[4]