Search

We present the digital slot — a tool for the development of new hydraulic fracturing technologies via digitization of slurry flow in narrow channels. We consider slurry containing fluid, proppant, and fiber components. The flow is described by a continuum mathematical model based on the lubrication theory. The numerical algorithm utilizes Lagrangian approach with finite volume pressure solver. We present the results of laboratory validation and simulation examples showing the key effects affecting solids transport in hydraulic fracturing: settling, bridging, gravity slumping, materials degradation, viscosity contrast, and bank formation.

In-Situ Channelization (ISC) phenomenon comprises a segregation of proppant and fiber-laden slurry in a hydraulic fracture during fracture closure. The segregation can lead to the creation of highly conductive open channels in the proppant pack and can significantly alter the fracture conductivity. Simulating ISC in a fracturing simulator can help maximize channeled areas, thus suggesting a higher production. The nature of ISC represents the slurry bridging at static conditions due to wall roughness and heterogeneities in proppant and fiber distribution. We demonstrate the development of the static bridging model, which we refer to as anchoring. The model is based on the physical principles, namely the force balance. The parameters governing the phenomenon include slurry composition, temperature, fracture walls surface roughness and orientation. Pixel-type approach to laboratory testing is introduced, which aids in the simplification of the model description and the implementation. Fracture waviness and roughness were found to affect the channelization, with fracture inclination angle being the most contributing factor. The model was extended to high temperatures, allowing simulations in the whole working ranges. Verification and validation showed fairly good reproduction of experimental data with the model, with tolerance of the anchoring event determination being within 5 ppt of fiber concentration. Simulations of hydraulic fracturing in the fracturing simulator with ISC model enabled revealed that ISC phenomenon has significant effect in treatments with low viscous fluids (e.g., linear gel or slick water). Meanwhile the effect diminishes as the reservoir temperature increases.

Acid fracturing is a widely accepted method for stimulation of carbonate reservoirs. A new high-resolution fracture hydrodynamics and in-situ kinetics model integrated on a reservoir-centric exploration and production platform improves acid fracturing simulation accuracy and performance for completion, stimulation, and reservoir engineering groups. This paper describes key features of the new acid fracturing model and the workflows that have been enabled on the E&P platform. We demonstrate that the new acid fracturing model can simulate the key effects of acid fracturing at a new level of fidelity and quality. For example, it reproduces viscous fingering effects that occur naturally when alternating fluid systems of different viscosities are pumped into the fracture. The model simulates diverting agents that reduce leakoff in the fracture area and their effects on fracture geometry. Combining the 3D earth model in the E&P platform and high-resolution simulator allows the modeling of small-scale heterogeneities that affect fracture conductivity with a high level of accuracy. The model is also capable of simulating hybrid acid-proppant treatments. Finally, a fluid and materials database is incorporated to capture the impact of modern acid systems and diversion agents. The new model was validated against the results of laboratory experiments and published data. The first results of the platform stimulation-to-production workflow implementation are presented for a formation with high calcite content. The new approach enables engineers to evaluate completion and stimulation designs directly by quantifying the impact on hydrocarbon production and seamlessly integrates carbonates completion design and reservoir engineering disciplines. The novel high-fidelity approach to acid leakoff, diversion systems, and rheology of different fluid mixtures significantly extends the design and evaluation tools for acid fracturing treatments in carbonate formations. Integrating the acid fracture model and E&P platform enables simulation of multiple acid treatments all the way to production evaluation and opens the path towards optimal design of single- and multiple-well treatments.

A new semi-analytical model developed allows making fast modeling of the heterogeneous reservoirs, drained by a single horizontal well with multiple transverse hydraulic fractures. It is assumed that: –the flow in the reservoir obeys Darcy law;–the fluid contains only one phase;–the reservoir permeability tensor is a function of the variable, directed along the horizontal wellbore;–the well trajectory is not a straight line;–the wellbore has finite conductivity The proposed model is fast in terms of the execution time and the time required to build a new case. In the first section of this article a description of the solution method is given. The second part is dedicated to validating the proposed model. The recognized finite-difference hydrodynamic simulator (FDS) was used as reference software, though fhe model and FDS are not competitors because of their differing applicability. For this reason the execution times of the FDS and the Advanced Horizontal Well (AHW) model are not compared with one another. More significant is that using this model one can generate a new case in fifteen minutes even when the properties of the reservoir are complex and when there are multiple fractures. The primary focus of the AHW model is a single well productivity index analysis, and candidate selection for stimulation.