Initial Period Of Production Research Articles

Hess’ ‘Drainage’ Wells Show Strong Production but Face Cost and Spacing Challenges

A new kind of horizontal well has emerged from an experiment in North Dakota’s Bakken and Three Forks shales. It uses an uncemented slotted liner to produce hydrocarbons by intercepting fractures that originate from offset wells. Hess Corp. revealed the concept over 2 years ago, confirming at an SPE conference that crude was flowing from the pilot well. The New York City-headquartered oil company also announced that additional trials were in progress, though it withheld specific production figures. The wait for those key details is now over. At the recent Unconventional Resources Technology Conference (URTeC) in Houston, Hess presented its first technical paper on the augmented drainage development (ADD) pilots which it claims have proven the approach to be, at the very least, a technical success. In URTeC 4044110, the company’s authors underlined their optimism in noting that ADD wells “could lead to a step change in productivity and recovery in unconventional developments.” Hess acknowledges that economic and technical hurdles currently stand in the way of that vision. But the upbeat assessment is backed by impressive production data from its inaugural pilot launched in 2021. Placed about 240 ft between two actively stimulated Middle Bakken wells, the first drainage well exceeded expectations, averaging nearly 1,700 B/D of crude in the first 8 days of flowback. Output fell to about 1,500 B/D over the next few days as the nearest actively stimulated well—called a “standard well” by Hess—began its flowback. This was one of several confirmations that the wells were in direct communication. “A lot of bets were lost on this well—maybe not by me, but by a lot of people,” remarked Craig Cipolla, a principle completions engineering advisor for Hess. Cipolla presented the company’s findings at the conference this past summer. He said the ADD well also pumped out about as much frac sand as is seen in a typical shale well, which in addition to tracer data, verified that it was well propped. During the initial production period, the first ADD well achieved about 85% of the output of the offsetting standard wells on the pad. Although this figure eventually dropped to just over 40% over the next 2 years, it was enough for Hess to consider the concept validated. Based on the results from all three pilots, Hess estimates ADD wells in the Bakken can be expected to achieve 10 to 45% of the output of typical hydraulically fractured horizontal wells. On the low end, the oil recovered from distant and low-conductivity fractures likely won’t justify drilling even a wellbore as barebones as the ADD concept calls for. Conversely, if a drainage well produces too much oil it is a sign that well spacing is too tight and that it is overly competing for resources with more-expensive offsets. This is likely the story of why the first ADD well came on so strong.

Permeability Evolution of Porous Sandstone in the Initial Period of Oil Production: Comparison of Well Test and Coreflooding Data

Permeability prediction in hydrocarbon production is an important task. The decrease in permeability due to depletion leads to an increase in the time of oil or gas production. Permeability models usually are obtained by various methods, including coreflooding and the field testing of wells. The results of previous studies have shown that permeability has a power-law or exponential dependence on effective pressure; however, the difficulty in predicting permeability is associated with hysteresis, the causes of which remain not fully understood. To model permeability, as well as explain the causes of hysteresis, some authors have used mechanical reservoir models. Studies have shown that these models cannot be applied with small fluctuations in effective pressures in the initial period of hydrocarbon production. In this work, based on the analysis of well test data, we came to the conclusion that in the initial period of production under constant thermobaric conditions, the permeability of a slightly clayey terrigenous reservoir depends on the amount of fluid produced. A model has been obtained that describes the change in permeability in the initial period of oil production. Core samples were flooded to confirm the model. Coreflooding showed high convergence of the model obtained from well test data. With computed tomography (CT) and scanning electron microscope (SEM), the properties and structure of the core were studied, and it was found that the main reason for the decrease in the permeability of slightly clayey rocks in the initial period of production is the migration of natural colloids.

Identification of Seepage Mechanisms for Natural Gas Huff-n-Puff and Flooding Processes in Hydrophilic Reservoirs With Low and Ultra-Low Permeabilities

Abstract Hydrocarbon gas flooding/Huff-n-Puff (HNP) can improve the oil recovery in the unconventional reservoirs. Here, the mechanisms accounting for fluid flow in the low-permeability and ultra-low permeability reservoirs were experimentally and theoretically investigated. Core plugs collected from a typical China oilfield were utilized for the experiments. Additionally, methane was used as the injection agent to conduct natural gas HNP/displacement experiments. The results indicated that the use of natural gas as an energy supplement agent and the HNP development method can effectively improve the recovery efficiency of the aforementioned two types of reservoirs. During the HNP process, the oil recovery is effectively enhanced mainly in the first round and second round. Meanwhile, during gas injection and HNP, natural gas can evidently weaken the extraction and reduce the precipitation of heavy components. However, the natural gas injection can establish an effective driving pressure system in low-permeability core plugs, and the interaction between natural gas and oil can change the mobility ratio. Furthermore, it aids in avoiding viscous fingering and premature breakthroughs. Moreover, the oil can be sandwiched between the interface of the gas and water phases to form a slip channel in a hydrophilic core sample, which can quickly produce oil. Finally, a numerical model was developed by considering the reservoir parameters of Changqing Oilfield, China. The oil recovery after eight rounds of CH4 HNP was 80% higher than that achieved via depletion development. Additionally, the oil recovery curves are especially similar in the previous three HNP rounds. These curves show obvious differences from the fourth round onwards, which indicates that the asphaltene deposition and CH4 diffusion slightly affect the oil recovery factor during the initial production period.

Sand production evaluation during gas production from natural gas hydrates

Natural gas hydrates are a potential energy resource that can ease the energy crisis, and their development has attracted an increasing amount of worldwide attention. Submarine natural gas hydrates are mainly stored in the shallow strata of deep water, and the reservoirs are poorly cemented and have low strengths. In addition, the dissociation of natural gas hydrates during the development process can greatly reduce the strength of these reservoirs. As a result, sand production easily occurs. Based on the geomechanical characteristics of submarine hydrate reservoirs, this study analyzed the changes in the reservoir characteristics caused by the coupling effect of a multiphysical field and the dissociation of natural gas hydrates during the development of natural gas hydrate reservoirs. A numerical simulation was used to analyze the characteristics that determine the plastic yielding of the rock surrounding the well and the laws of sand production during gas production from hydrate reservoirs. The results showed that with the increase in the pressure drop during production and the difference between horizontal in situ stresses in the reservoirs, the stress concentration on the surrounding rocks of the wells will increase, enabling the reservoirs to more easily produce sand. Furthermore, an increasing pressure drop during production also promotes hydrate dissociation and lowers the strength of the rock surrounding the well, causing large-scale plastic yielding in the rock surrounding a well; consequently, this causes sand production. Moreover, with higher bottom-hole temperatures and reservoir permeabilities, the natural gas hydrates will dissociate faster, which accelerates the strength reduction of the reservoir, and sand will be more easily produced. During the initial period of production, the intensity of sand production has no defined relationship with the initial hydrate saturation. However, as the production time increases, especially after the dissociation of the hydrates near the well, and with higher initial hydrate saturation, the sand production issue becomes more serious. These research results provide a theoretical basis for the strategic formulation of sand control measures during natural gas hydrate production.

Financing strategies for coal-electricity supply chain under yield uncertainty

The financing strategies for a coal-electricity supply chain in which the coal company has capital constraint and faces yield uncertainty were studied. We propose an advance payment mechanism: in the coal company’s initial production period, the electricity company provides advance payment to the coal company, and the coal company pays interest to the electricity company as the risk compensation. The optimal operation strategies for the coal company and the electricity company under the advance payment mechanism are derived and compared with those under the bank loan financing case. We find that, the expected profit functions of the coal company and the electricity company under the advance payment mechanism are the same with those under the case that the coal company has enough capital; under the advance payment mechanism, the profits of the coal company and the electricity company are higher than those under the bank financing case. We also discuss the compensation interest rate of the advance payment and the ordering and production quantities under the advance payment mechanism.

A model for coupling reservoir inflow and wellbore flow in fishbone wells

A coupling model is proposed in this paper by using the Green Function and Newman’s product principle, and the solution method is provided here as well. This model can be used to describe the reservoir inflow and wellbore flow for fishbone wells in an unsteady flow or pseudo-steady flow state. A case study indicates that the bottom hole pressure declines quickly in the unsteady flow period which is very short. The pressure drop per unit time remains unchanged under the pseudo-steady flow conditions. The distribution of flow rate along the main wellbore shows a wave shape under the unsteady flow condition, and the flow rate distribution in each branch is similar. The flow rate distribution along the main wellbore is irregular “U” shaped under the pseudo-steady flow condition, and the space-symmetrical branches have the same flow distribution pattern. In the initial production period, the flow rate increases significantly as the length of branches and the angle between branches and the main wellbore increase. As the production continues, the length and angle of branches have only a slight effect on the flow in fishbone wells.

A concentração do mercado de biodiesel no Brasil

Brazil, despite having several potential sources for biodiesel production, has prioritized the use of oleaginous that can generate more workforce jobs including regions that are outside of the economic development process. With this focus and to regulate the market, the National Petrol Agency, since 2005, stipulated that the sale of this product would be happen only through auctions. This article aims to analyze and discuss this concentration of companies that participated of the sixteen auctions already realized. For that, it was used the concentration indicators like Gini’s and Theil’s indexes, and the Partial Concentration index (PC). It was observed that the biodiesel market in Brazil seems to be more concentrated because of its least quantity of qualified companies and for their capacities of competing in an initial period of production. However, from the 4th auction the quantity of participant companies able to produce and participate of the auctions increase and, consequently the concentration level decrease, by the CR4 index. However, Gini’s and Theil‘s indexes, that also consider the sold volumes, demonstrate a concentration increase still in a moderate level. Key words: auctions, familiar agriculture, index of Gini, index of Theil.

A concentração do mercado de biodiesel no Brasil

Brazil, despite having several potential sources for biodiesel production, has prioritized the use of oleaginous that can generate more workforce jobs including regions that are outside of the economic development process. With this focus and to regulate the market, the National Petrol Agency, since 2005, stipulated that the sale of this product would be happen only through auctions. This article aims to analyze and discuss this concentration of companies that participated of the sixteen auctions already realized. For that, it was used the concentration indicators like Gini’s and Theil’s indexes, and the Partial Concentration index (PC). It was observed that the biodiesel market in Brazil seems to be more concentrated because of its least quantity of qualified companies and for their capacities of competing in an initial period of production. However, from the 4th auction the quantity of participant companies able to produce and participate of the auctions increase and, consequently the concentration level decrease, by the CR4 index. However, Gini’s and Theil‘s indexes, that also consider the sold volumes, demonstrate a concentration increase still in a moderate level. Key words: auctions, familiar agriculture, index of Gini, index of Theil.

Fertility and hatchability of eggs laid in the pullet-to-breeder transition period and in the initial production period

The initial eggs produced by broiler breeder hens are relatively small compared with later in the production cycle. An evaluation of indices related to hatchability is required when these eggs are to be used for the production of broiler chicks. Two experiments were conducted to evaluate characteristics related to the hatchability of eggs from pullet-to-breeder transition phase, at 25 and 27 weeks of age, and from the peak of production period and five weeks later, at 32 and 37 weeks of age. Eggs from birds 25 weeks had a lesser fertility in Experiment 1. Mortality occurred unevenly in early (1–5 days), middle (6–17 days) and late (18–21 days) incubation, and greater mortality was observed after the internal membrane was ruptured. The younger the hen, the lighter the egg, chick, and shell, and the longer the time required to complete the hatching process. In Experiment 2, greater mortalities were observed at the early period (1–5 days) and after “pipping” of the internal and external membranes. Embryos from heavy eggs of breeder hens 37 weeks of age took less time to complete the hatching process. Results indicated the larger the egg, the heavier the chick and shell, and the lesser the shell percentage. As breeder age advanced, characteristics related to egg fertility and hatchability improved.

Dimethyl sulfide metabolism in salt marsh sediments

Anoxic sediment slurries prepared from Spartina salt marsh soils contained dimethyl sulfide (DMS) at concentrations ranging from 1 to 10 μM. DMS was produced in slurries over the initial 1–24 h incubation. After the initial period of production, DMS decreased to undetectable levels and methane thiol (MSH) was produced. Inhibition of methanogenesis caused a 20% decrease in the rate of DMS consumption, while inhibition of sulfate reduction caused a 80% decrease in DMS consumption. When sulfate reduction and methanogenesis were simultaneously inhibited, DMS did not decrease. DMS contributed about 28% to the methane production rate, while DMS probably contributed only 1% or less to the sulfate reduction rate. Incubation of the sediment slurries under an atmosphere of air resulted in similar DMS consumption compared to anaerobic incubations, but MSH and CH4 were not evolved. Sediments from the marsh released significant quantities of DMS when treated with cold alkali, indicating that potentially significant sources of DMS existed in the sediments. Values of base-hydrolyzable DMS as high as 190 μmol per liter of sediment were observed near the sediment surface, and values always decreased with depth in the sediment. Simple flux experiments with small intact sediment cores, showed that DMS was emitted from the marsh surface when cores were injected with glutaraldehyde or molybdate and 2-bromoethanesulfonate (BES), but nit when cores were left uninhibited. These results showed that DMS was readily metabolized by microbes in marsh sediments and that this metabolism may be responsible for reducing the emission of DMS from the marsh surface.

Dimethyl sulfide metabolism in salt marsh sediments

Abstract Anoxic sediment slurries prepared from Spartina salt marsh soils contained dimethyl sulfide (DMS) at concentrations ranging from 1 to 10 μM. DMS was produced in slurries over the initial 1–24 h incubation. After the initial period of production, DMS decreased to undetectable levels and methane thiol (MSH) was produced. Inhibition of methanogenesis caused a 20% decrease in the rate of DMS consumption, while inhibition of sulfate reduction caused a 80% decrease in DMS consumption. When sulfate reduction and methanogenesis were simultaneously inhibited, DMS did not decrease. DMS contributed about 28% to the methane production rate, while DMS probably contributed only 1% or less to the sulfate reduction rate. Incubation of the sediment slurries under an atmosphere of air resulted in similar DMS consumption compared to anaerobic incubations, but MSH and CH 4 were not evolved. Sediments from the marsh released significant quantities of DMS when treated with cold alkali, indicating that potentially significant sources of DMS existed in the sediments. Values of base-hydrolyzable DMS as high as 190 μmol per liter of sediment were observed near the sediment surface, and values always decreased with depth in the sediment. Simple flux experiments with small intact sediment cores, showed that DMS was emitted from the marsh surface when cores were injected with glutaraldehyde or molybdate and 2-bromoethanesulfonate (BES), but nit when cores were left uninhibited. These results showed that DMS was readily metabolized by microbes in marsh sediments and that this metabolism may be responsible for reducing the emission of DMS from the marsh surface.