Short-Term and Long-Term Mechanical Models of Wellbores Considering Cement Consolidation and Formation Creep

SPE Journal ◽  
2019 ◽  
Vol 24 (05) ◽  
pp. 2064-2082
Author(s):  
Wenjun Huang ◽  
Deli Gao ◽  
Yinghua Liu
Keyword(s):  
Governing Equation ◽  
Oil And Gas ◽  
Coupling Effect ◽  
Superposition Method ◽  
Short Term ◽  
Consolidation Process ◽  
Term Model ◽  
Initial Strains ◽  
Wellbore Failure

Summary With oil and gas wells extending deeper and deeper, downhole conditions become increasingly complicated, and thus increasingly sophisticated wellbore models are needed. Current wellbore models usually neglect the coupling effect in the cement–consolidation process and do not sufficiently consider the whole operation process of the wellbore. To overcome these shortcomings, short–term and long–term mechanical wellbore models while considering the relevant stages in wellbore life are built. In the short–term model, wellbore–operation stages include casing running, cement displacement, and cement consolidation. The governing equation of cement consolidation while considering the coupling effect between cement hardening and volume change is presented. In the long–term model, the governing equation of formation creep while considering prestresses and initial strains is given. The elastic/viscoelastic–correspondence principle and stress–superposition method are used to simplify the derivation. Next, the effects of relevant factors on short–term and long–term wellbore stresses are analyzed. The results show that wellbore stresses caused by cement consolidation will be underestimated when the coupling effects are neglected. The most vulnerable positions for wellbore failure are on different cylinder elements under different wellbore stages. Wellbore properties, short–term stresses, and formation creep greatly affect wellbore mechanical behaviors. Therefore, the new model provides an important basis for wellbore–failure prediction and optimal design.

Abstract 039: Comparison of Costs & Outcomes of Dapagliflozin With Dipeptidyl Peptidase-4 Inhibitors Added to Metformin Using a Short-term Cost-effectiveness Model

2017 ◽  
Vol 10 (suppl_3) ◽  
Author(s):  
Abhiroop Chakravarty ◽  
Mohini Rastogi ◽  
Praveen Dhankhar ◽  
Kelly Bell
Keyword(s):  
Cost Effectiveness ◽  
Cost Saving ◽  
Economic Impact ◽  
Costs And Benefits ◽  
Short Term ◽  
End Points ◽  
Dipeptidyl Peptidase 4 ◽  
Term Model ◽  
Dipeptidyl Peptidase 4 Inhibitors

Background: Several long-term models have been developed to compare the economic impact of alternative anti-diabetic treatments. However short-term models, based on actual trial data, might give more accurate results and be preferable over long-term models for estimating costs and benefits in short term. Objective: To assess the economic impact of the antidiabetic drug dapagliflozin (DAPA), a sodium-glucose cotransporter-2 (SGLT-2) inhibitor, and dipeptidyl peptidase-4 inhibitors (DPP-4i) combined with metformin in the treatment of T2D. Methods: A short-term decision-analytic model with one year time horizon was developed using a payer’s perspective for United States (US). Costs and benefits associated with four clinical end points (glycated hemoglobin [HbA1c], body weight, systolic blood pressure (SBP), and risk of hypoglycemia) were evaluated in the analysis. A network meta-analysis was utilized to evaluate the impact of DAPA vs. DPP-4i on these clinical end points. Data for costs and QALYs associated with a per unit change in these clinical end points was taken from published literature. Drug prices were taken from annual wholesale price list. All costs were inflation-adjusted to 2016 costs using the medical care component of the consumer price index. Total costs (medical and drug), total QALYs, and incremental cost effectiveness ratios (ICERs) were estimated. Sensitivity analyses were performed as well. Results from the short-term model were compared with long term models published for these treatments. Results: Total annual medical cost for DAPA was $1,119 less than that for DPP-4i, with the difference mainly attributable to cost associated with weight change ($860). Treatment with DAPA resulted in an average QALY gain of 0.0587 per treated patient compared to DPP-4i. DAPA was cost-saving when compared to DPP-4i. Among all the four clinical end points, change in weight had the greatest impact on total annual costs and ICERs. Probabilistic sensitivity analysis demonstrated that total annual cost for DAPA was less than that for DPP-4i in more than 97% of simulations and DAPA had a 97% probability of being cost-saving compared with DPP-4i. Results from the short-term model were similar to published long term models. Conclusions: Our analysis showed that DAPA was cost saving when compared with DPP-4i in the US setting. Furthermore, the results suggest that among the four composite clinical endpoints, change in weight had greater impact on cost-effectiveness results. In addition, our short-term model provides results similar to published long term models.

scholarly journals Analysis of Ziswaf, Production Index and Sharia Stock Index on Economic Growth

2019 ◽  
Vol 1 (2) ◽  
pp. 221-242
Author(s):  
Purbawati Setyaningsih ◽  
Roikhan Mochamad Aziz ◽  
Puji Hadiyati
Keyword(s):  
Economic Growth ◽  
Stock Index ◽  
Economic Activities ◽  
Negative Effects ◽  
Short Term ◽  
Production Index ◽  
Positive Effects ◽  
Term Model ◽  
Long Run

This study analyzes the influence ZISWAF, Gini ratio, the total export value, the index of industrial production, sharia stock index investment to GDP growth, in the short and long term. Qualitative data were taken from BPS, Baznas, ACT Global Waqf, the FSA from March 2006 until December 2017 using the methodology of The Error Correction Model (ECM). The results of this study indicate that the variable Gini Ratio, Ziswaf, Total exports, Production Index and Sharia Stock Index on GDP economic growth have significant and positive effects in the long term and the short term. Meaning that these variables have a relationship with GDP economic growth. If the variable decreases or slows down-then GDP economic growth also. While total exports have insignificant effects and negative effects on GDP economic growth. The R-square regression value of the long-term model produces a proportion of 96 percent, the short-term model produces a proportion of 97 percent. Both in the long-run and short-run models, the highest coefficient value is the value of the Gini ratio with 4.941522 and 0.348043. All positive coefficients, Gini ratio variables, ziswaf and production index have a significant effect on gdp, total exports and sharia stock indexes do not have a significant effect on gdp both in the long and short-term models. It implies in the future, fiscal economic policy makers to economic growth that opened a lot of employment, by encouraging resource based economic activities of Indonesia's largest export-oriented agriculture and mining. Good Corporate goverment should do so gini ratio of the areas surrounding the economy improved and people kesejahtaeraan increase.

An institutional investor's perspective on oil and gas investment

2011 ◽  
Vol 51 (2) ◽  
pp. 712
Author(s):  
Andy Zhmurovsky
Keyword(s):  
Oil And Gas ◽  
Investment Horizon ◽  
Short Term ◽  
Investment Environment ◽  
Quarterly Earnings ◽  
Long Run ◽  
Surface Performance

From the perspective of an institutional oil and gas investor, investing is like creating a partnership. Given the long-term investment horizon, the focus is on creating value in the long run and on setting up the stage to withstand short-term volatility and uncertainty. A producer/developer is able to better focus on protecting its assets instead of managing the market’s expectations and quarterly earnings or KPIs. Also, projecting sub-surface performance is highly interpretive and adds another layer of risk to the already complex investment environment.

PENGARUH TINGKAT BUNGA DAN PENDAPATAN NASIONAL TERHADAP TABUNGAN DI INDONESIA, MALAYSIA DAN THAILAND

2015 ◽  
Vol 19 (2) ◽  
pp. 91-102
Author(s):  
Lumadya Adi ◽  
Wiwik Budiarti
Keyword(s):  
Interest Rates ◽  
National Income ◽  
Analysis Tool ◽  
Short Term ◽  
Partial Adjustment ◽  
Term Model ◽  
Partial Adjustment Model ◽  
Domestic Savings ◽  
Independent Variable

 The purpose of the study: 1 Testing the effect of interest rates in the short term and the long-term domestic savings in Indonesia, Malaysia and Thailand. 2 Testing the influence of national income in the short term and the long-term domestic savings in Indonesia, Malaysia and Thailand. Analysis tool is a dynamic econometric model of the Partial Adjustment Model (PAM). This model applies when the independent variable is the lag of the dependent variable and must be positive and  statistically significant. The results of the analysis as follows:  1. For Indonesia, short-term and long-term national income significantly influence domestic savings  2. For Indonesia, the short-term and long-term interest rate has no significant effect on domestic savings.  3. For Malaysia, the national income in the short term a significant effect on domestic savings, but can not be used long-term model.  4. For Malaysia, the short-term interest rates have a significant effect on domestic savings, but can not be used long-term model.  5. For Thailand, in the short-term and long-term national income no significant effect on domestic savings. 6. For Thailand, in the short term and long term interest rates have a significant effect on domestic savings.

A New Decline-Curve-Analysis Method for Layered Reservoirs

SPE Journal ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 1657-1669
Author(s):  
Kittiphong Jongkittinarukorn ◽  
Nick Last ◽  
Freddy Humberto Escobar ◽  
Kreangkrai Maneeintr
Keyword(s):  
Flow Rate ◽  
History Matching ◽  
Oil And Gas ◽  
Single Layer ◽  
Short Term ◽  
Reserve Estimation ◽  
Early Stages ◽  
Decline Curve ◽  
Decline Rate

Summary This study presents a new method to improve production forecasts and reserve estimation for a multilayer well in the early stages of production using the Arps (1945) hyperbolic decline method to model the decline rate of each layer. The method can be applied to both oil and gas wells. The new approach generates the profiles of the instantaneous decline rate (D) and instantaneous decline-curve exponent (b) from the historical flow rate (q). Because of the inherent noise in the production data, a regression technique is applied to smooth the flow-rate data, and the analysis is performed on the smoothed data. History matching is performed not only on the profile of q but also on the profiles of D and b. This results in the unique decline parameters (qi,Di, and b) for each layer. For a multilayer well, the values of D and b vary with time, which means that the well's performance cannot be modeled using a conventional single-layer-well approach. Furthermore, the well-known nonuniqueness problem from history matching is magnified in a multilayer well: Many models can successfully match the production profile in the short-term but fail to match it in the longer term. Only the correct model can match the profiles of q, D, and b over both the short-term and the long-term. The proposed method provides the correct unique decline parameters (qi,Di, and b) for each layer, during the early stages of production, and these parameters are then valid for the life of the well. The method works well for both synthetic examples and actual field data. The novelty of the new methodology is the ability to provide the decline parameters for each layer at an early stages of production that can then be used for production forecasting in the long-term. The nonuniqueness problem from history matching is solved.

scholarly journals Temperature dependence of coastal wetland ecosystem respiration confounded by tidal activities: a temporal perspective

2013 ◽  
Vol 10 (3) ◽  
pp. 4515-4537 ◽  
Author(s):  
X. Xie ◽  
M.-Q. Zhang ◽  
B. Zhao ◽  
H.-Q. Guo
Keyword(s):  
Time Scales ◽  
Temperature Sensitivity ◽  
Coastal Wetland ◽  
Ecosystem Respiration ◽  
Tidal Effect ◽  
Short Term ◽  
Confounding Effect ◽  
Hydrological Condition ◽  
Term Model

Abstract. Variations of temperature and hydrological conditions result in the fluctuation of ecosystem respiration (ER). Temperature sensitivity is widely used to describe ER-temperature relationship, but hydrological condition with similar dynamics as temperature could cause confounding effect. Many researchers have made comparisons between long-term and short-term models to show the confounding effect. However, how temperature sensitivity is confounded by hydrological condition in different time scales remains unknown. In this study, data from two coastal wetland sites were used. By comparing the variations of temperature and tidal influence at three time scales (monthly, seasonal and half-yearly), we found that: (1) the co-variation of temperature and other environmental factors accounted for the long-term confounding effect, and (2) the small variances of temperature in short time scale explained the short-term confounding effect. As a result of the long-term confounding effect, greater system errors were introduced in long-term model than short-term did. As the temperature sensitivity derived from long-term "ignored" the alternation of main driving factor of ER, temperature influence on ER was overestimated while the tidal influence was underestimated. Tidal activities had great influences on ER when the variances of temperature were small. If short-term model without tidal effect was applied, short-term confounding effect was inevitable. Compared to the long-term model (half-yearly), short-term model (monthly without tidal effect) performed better that helped reduce the long-term confounding effect, and integrating a proper secondary factor like tide would further reduce the short-term confounding effect.

scholarly journals ANALISIS PENENTUAN SUBSEKTOR PRIORITAS PADA BIDANG KELAUTAN INDONESIA (PENDEKATAN DETERMINISTIK INPUT-OUTPUT)

2018 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Aulia Keiko Hubbansyah
Keyword(s):  
Oil And Gas ◽  
Input Output ◽  
Fish Processing ◽  
Short Term ◽  
Marine Tourism ◽  
Output Multiplier ◽  
Multiplier Effect ◽  
Backward Linkages ◽  
Offshore Mining

The aim of this study is to determine priority subsectors in the field of Indonesian marine. The analysis is done by input-output approach. This study has found several priority subsectors classified into two groups, namely short-term and long-term priority subsector groups. Short-term priority subsectors group in the Indonesian marine sector include fish processing and preservation industries, marine tourism, marine and fisheries support, marine and fisheries education and research services, and fisheries services. Meanwhile, for the long-term priority subsectors group the Indonesian marine sector comprises oil and gas mining and refining, marine trade services, offshore mining, fishery services and shrimp industry.Keywords: Input-Output, Multiplier Effect, Backward Linkages, Forward Linkages

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

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