As the offshore oil and gas fields are maturing, the water production rate from the reservoir is increasing progressively year by year. The methane hydrate formation in water-continuous systems has become a significant flow assurance issue for offshore oil and gas production. In this study, a group of methane hydrate formation experiments are designed to study characteristics of hydrate formation in the water-continuous flow loop, which were performed under void fractions from 2.6 to 5.0%, flow velocities from 1.24 to 1.57 m/s, subcooling temperatures from 4.5 to 7.2 °C, and hydrate particle concentration from 0 to 0.14 kg/kg. The methane hydrate formation process is considered as a mass transfer process, and the multiple influencing factors on the hydrate formation are analyzed experimentally, such as flow velocity, subcooling temperature, and hydrate particle concentration. Results show that higher flow velocity induces higher hydrate formation rate. Higher hydrate particle concentration results in lower hydrate formation rate. Thus, an integrated mass transfer coefficient is proposed, including the effect of the hydrate particle concentration and the flow velocity. In this work, the effect of subcoolings on the integrated mass transfer coefficient is found to be negligible. A corresponding mass transfer-limited hydrate formation model is proposed to predict methane hydrate formation in the water-continuous system, which is a function of the proposed integrated mass transfer coefficient, flow velocity, hydrate particle concentration, subcooling, and gas−liquid interfacial area. After comparing with experimental data, the proposed hydrate formation model shows its good agreement with experimental data.

In the northern part of Erzhong District in Karamay conglomerate oilfield, Xinjiang, China, ASP pilot tests have been conducted in 13 wells in a pilot area of 0.031 square kilometers since September 1994. The pilot area was developed through combining laboratory results in recent years with specific conditions in the field. This test is aimed to verify oil displacement efficiency of ASP and related reservoir behaviors, to improve production techniques necessary to obtain remaining oil from conglomerate reservoirs, and to provide data for economic feasibility evaluation. P. 385

Alkylaryl sulfonate is a typical family of surfactants used for chemically enhanced oil recovery (EOR). While it has been widely used in surfactant–polymer flooding at Karamay Oilfield (40 °C, salinity 14,000 mg/L), its aggregation behavior in aqueous solutions and the contribution of aggregation to EOR have not been investigated so far. In this study, raw naphthenic arylsulfonate (NAS) and its purified derivatives, alkylaryl monosulfonate (AMS) and alkylaryl disulfonate (ADS), were examined under simulated temperature and salinity environment of Karamay reservoirs for their micellar aggregation behavior through measuring surface tension, micellar size, and micellar aggregation number. It was found that all three alkylaryl sulfonate surfactants could significantly lower the surface tension of their aqueous solutions. Also, it has been noted that an elevation both in temperature and salinity reduced the surface tension and critical micellar concentration. The results promote understanding of the performance of NAS and screening surfactants in EOR.

This work investigated the element distribution of perthite from the Upper Triassic Yanchang Formation tight sandstone in the Ordos Basin of northern China by field emission scanning electron microscopy (FE‐SEM) and energy dispersive spectrometer (EDS). FE‐SEM results indicate significant differences in the morphology of Na‐rich feldspar when K‐rich feldspar is the main component of the perthite. EDS results show that different types of perthite have clearly defined differences on different element indexes. Additionally, indexes such as average‐weight‐K (K‐rich)/Na (Na‐rich), maximum‐weight‐K (Na‐rich)/Na (Na‐rich) and average‐atomic‐K (K‐rich)/Na(Na‐rich) might be the most effective ones to identify perthite types. Perthite is divided into six main types, i.e., perthite with thick parallel stripe distribution, with thin parallel stripe distribution, with lumpy stripe distribution, with dendritic stripe distribution, with encircling stripe distribution, and with mixed stripe distribution.