Abstract Recent studies have indicated that the injection of carbon dioxide (CO 2 ) can lead to increased oil recovery in fractured shale reservoirs following natural depletion. Despite advancements understanding mass exchange processes subsurface formations, there remains a knowledge gap concerning disparities these between matrix and fractures at pore scale formations with varying permeability. This study aims experimentally investigate CO diffusion behaviors situ through huff ‘n’ puff...

ABSTRACT China's Yinggehai Basin gas field is in the middle and late stages of development has a large CO 2 sequestration potential. Moreover, recovery low, it can be further enhanced by injecting . In order to study ratio realize storage, numerical simulation studies were carried out on three types reservoirs Dongfang A field, including hypotonic, mesotonic depletion, water intrusion. The results show that: (1) competitive adsorption improves storage CH 4 low‐permeability reservoirs;...

In shale gas reservoir development, determination of hydraulic fracture geometry for horizontal wells is a demanding yet challenging task. One type approach optimization based on simulation. To improve efficiency and accuracy, an automatic robust procedure integrating the gradient descent method with simulation has been developed. Fractured models were constructed using “Multiple INteracting Continua” method, whereby in-house simulator was implemented to model multiple transport mechanisms...

Summary Most simulators currently use the advection/diffusion model (ADM), where total flux comprises Darcian advection and Fickian diffusion. However, significant errors can arise, especially for modeling diffusion processes in fractured unconventional reservoirs, if is modeled by conventional Fick’s law using molar concentration. Hence, we propose an improved multicomponent reservoirs to better quantify multiphase transport across fracture/matrix interface. We first give a modified...

Eighteen models based on two equations of state (EoS), three viscosity models, and four mixing rules were constructed to predict the viscosities natural gases at high temperature pressure (HTHP) conditions. For pure substances, parameters free volume (FV) entropy scaling (ES) found scale with molecular weight, which indicates that ordered behavior Peng-Robinson (PR) Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) propagates model. Predicting showed FV ES respectively combined...

Abstract A simulation study was carried out to investigate the temporal evolution of H 2 S in Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing field. Based on rock and fluid properties field, multilayered model built. The upper layer Jia-2 contains high concentration (27.2 g/m 3 ), lower Jia-1 low (14.0 mg/m ). There also low-permeability interlayer between Jia-2. multi-component characterizations for were implemented separately using...

Abstract Stress sensitivity of a naturally fractured reservoir is regarded as pronounced where pressure decrease induced by production believed to cause significant changes in fracture apertures. Most laboratory investigations suggest that would lead great loss conductivity and rapid decline. But till today, no such evidence from the practices has been documented; on contrary, there are some reported cases depletion could potentially maintain even increase extraction rate. To solve...

Abstract According to the characteristics of large amount and scattered discharge domestic sewage in rural residential environment, a treatment system based on modular constructed wetland was designed. The is composed three modules with scale 30 m 3 /d. plants are Arundo donax Typha, kinds filter media selected fill substrate. capacity effect were studied through experiments. results showed that had good sewage, average removal rates BOD5, COD, SS, NH3-N, TN TP 83.3%, 83.5%, 90.5%, 70%,...

Shale gas is an important component of unconventional oil and resources. Studying the imbibition behavior helpful to optimize flowback parameters enhance recovery. Recent studies have focused on shale matrix, pressure conditions discussed were mostly atmospheric. The initial begins from propped fractures but there are few working explaining in or phenomenon many wells exhibit higher productivity after a "soaking" period. Therefore, fracture samples designed for migration experiments. In...

Multiple enhanced oil recovery (EOR) mechanisms have been proposed for low salinity water flooding (LSWF) in sandstone porous media, but none of them could explain all cases. Previous linear regression analyses showed that multiple conditions must be met to activate intermediate oil-brine-rock interactions achieve incremental recovery, i.e., effect. However, the relationships found are merely "moderate" strength with high mean squared errors (MSE), which insufficient prediction analysis. In...

The control strategies of energy saving for filamentous sludge bulking were investigated in the A/O process under low dissolved oxygen (DO) with carbon/nitrogen (C/N) ratio, and dominant bacteria identified by using fluorescent situ hybridization. Initially, volume index reached nearly 500 mL/g serious occurred when DO value was 0.5 mg/L, Haliscomenobacter hydrossis as major sludge. Later on, compartment number increased aerobic zone, increasing this way DO, to bulking. Increasing 1 mg/L...

Despite the advancement in simulation technology, a great challenge for unconventional resources is relevant to correct representation of phase equilibria nanopores and effective implementation involved models. A novel equilibrium calculation framework based on successive substitution (SS)–Newton–Trust-Region (TR) method, coupled with critical property shifts capillary pressure, presented calculate behavior confined fluids nanopores. Moreover, an empirical relationship Lennard-Jones (12–6)...

Four types of gas injection experiments─CO2 flooding, N2 alternating CO2 and pre-slug flooding─were conducted in a 28.42 cm long core plug to study the production performances flooding model enhancing tight oil efficiency. Experimental results indicate that following. (1) For highest efficiency is achieved at rate 0.10 mL/min, with 68.75%, breakthrough time 0.33 PV, utilization 11.35 Mscf/stb, an 38.46%, 0.42 PV. (2) 56%, 7.97 Mscf/stb. (3) The 53.08% for flooding. A comparison experimental...

Abstract Gas injection has become the top choice for IOR/EOR pilots in tight oil reservoirs because of its high injectivity. The effects nanoconfinement and geomechanics are generally considered as non-negligible, but coupled resulting flow displacement still not well understood gas injection. We hence present a general compositional model simulator to investigate complicated multiphase multicomponent behaviors during reservoirs. This is able account vital physics unconventional reservoirs,...

Abstract Changqing Oilfield is the largest petroleum-producing field in China and one-third of its oil production attributed to formations with permeability lower than 1 mD. The rapid rate decline low recovery factor (RF) associated those require additional IOR/EOR measures besides waterflood. Based on promising results from recent gas injection pilots North America, we investigated feasibility formation (Chang 63) Oilfield. An eight-component fluid characterization, which fits both constant...