Experimental Study on Plugging Behavior of Degradable Diverters in Partially Open Fracture in Temporary Plugging and Diverting Fracturing.

Temporary plugging and diverting fracturing technology (TPDF) has been successfully applied to improve reservoir productivity. In real reservoirs, a considerable number of fractures have relatively rapidly decreasing fracture widths and closed ends. However, the plugging behavior of diverters in this typical fracture called the partially open fracture (POF) is still unclear because of the few related studies.

Optimization of Fracturing Fluid and Retarded Acid for Stimulating Tight Naturally Fractured Bedrock Reservoirs.

In tight naturally fractured bedrock reservoirs, hydrocarbons are typically stored in fractures, where hydraulic fracturing is needed to connect these fractures to the wellbore. The cross-linked gel is used as the fracturing fluid to reduce the fluid leak-off through natural fractures; however, it can cause formation damage due to its high content of residues after breaking. A synthetic polymer is introduced and evaluated that can maintain a high viscosity to minimize the leak-off , while having a low residue content after breaking.

High-Temperature-Resistant, Low-Concentration Water-Controlling Composite Cross-Linked Polyacrylamide Weak Gel System Prepared from Oilfield Sewage.

The polyacrylamide weak gel is an effective system to block a high-permeability layer, realize water control, and enhance oil recovery. However, its application is limited by poor temperature resistance and high polymer dosage. In this paper, an inorganic-organic composite cross-linking agent was synthesized by using Cr(III) and phenolic resin.

Study on the Effect of Fracturing Fluid on the Structure and Mechanical Properties of Igneous Rock.

Igneous rock oil and gas reservoirs have great development potential. Hydraulic fracturing is an important means for the development of these reservoirs. In the process of fracturing and increasing production, fracturing fluid is prone to a hydration reaction with clay minerals in igneous rock, and then, the structure and mechanical properties of the igneous rock are changed, affecting increased production.

Optimization and Evaluation of Stabilizers for Tight Water-Sensitive Conglomerate Reservoirs.

The upper Wuerhe formation in the Mahu-1 play is a tight conglomerate reservoir that has characteristics of low porosity and low permeability. During the early stage of field development, it has been noticed that horizontal wells typically have a high flowback ratio and an extremely low oil production rate during the early production, and this is likely attributed to the water-rock interaction that causes the closure of generated hydraulic fractures. In this study, a stabilizer and its dosage in a fracturing fluid are optimized, and its effect on clay antiswelling and rock stabilization is evaluated.

Field experiments of different fracturing designs in tight conglomerate oil reservoirs.

Mahu oilfield is currently the largest tight conglomerate reservoir in the world, where Ma-131 and Ma-18 plays are the first two commercially developed reservoirs. In order to reduce the cost and explore the best fracturing parameters, field experiments have been conducted in these two plays since 2017. Types of proppant and fracturing fluid, the slickwater ratio, and the fracture spacing are mainly changed for comparison, and fracturing effects are evaluated to establish a reference for developing neighboring plays in the Mahu oilfield.

Study on the Effect of Threshold Pressure Gradient on Remaining Oil Distribution in Heavy Oil Reservoirs.

Due to the spatial network structure, heavy oil has a high threshold pressure gradient when it flows through porous media, and the threshold pressure gradient plays a crucial role in the distribution of remaining oil. In previous study, the common methods to measure the threshold pressure gradient include the microflow-established differential pressure (MFEDP) method, capillary equilibrium method, and the percolation curve fitting method. In this study, a sample from the SZ36-1 oilfield was analyzed for the basic physical properties based on the comparison of the previous measurement to study the influence of mobility on the threshold pressure gradient and then an independently developed numerical simulator was established to study the effect of the threshold pressure gradient on the remaining oil distribution considering the permeability range, crude oil viscosity, well network deployment, well spacing, and fluid recovery rate.

Experimental and Simulation Studies on the Slug Flow in Curve Pipes.

This work focuses on the two-phase slug flow in the curve pipe, which is very common in oil/gas wells. In terms of oil and gas production, the unstable slug flow may cause several problems and reduce production. In the present work, slug flow experiments were conducted in several curve pipes for varying inflow angles and gas-liquid velocity ratios.

Adjoint traveltime tomography unravels a scenario of horizontal mantle flow beneath the North China craton.

The North China craton (NCC) was dominated by tectonic extension from late Cretaceous to Cenozoic, yet seismic studies on the relationship between crust extension and lithospheric mantle deformation are scarce. Here we present a three dimensional radially anisotropic model of NCC derived from adjoint traveltime tomography to address this issue. We find a prominent low S-wave velocity anomaly at lithospheric mantle depths beneath the Taihang Mountains, which extends eastward with a gradually decreasing amplitude.

Numerical Slug Flow Model of Curved Pipes with Experimental Validation.

The research for gas-liquid two-phase flow is very important for flow assurance and flow stability of chemical transportation. In terms of transportation pipelines, the curved section is a very significant part. Therefore, the present work proposes a transient slug flow model for the curve pipes, and we conducted some experiments to validate it.