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.

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.

Quantification of Uncertainty in Reserve Estimation From Decline Curve Analysis of Production Data for Unconventional Reservoirs

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yueming Cheng ◽  
W. John Lee ◽  
Duane A. McVay
Keyword(s):  
Oil And Gas ◽  
Curve Analysis ◽  
Production Data ◽  
Gas Wells ◽  
Reserve Estimation ◽  
Advanced Technique ◽  
Unconventional Resources ◽  
Decline Curve Analysis ◽  
Decline Curve ◽  
Reserve Estimates

Decline curve analysis is the most commonly used technique to estimate reserves from historical production data for the evaluation of unconventional resources. Quantifying the uncertainty of reserve estimates is an important issue in decline curve analysis, particularly for unconventional resources since forecasting future performance is particularly difficult in the analysis of unconventional oil or gas wells. Probabilistic approaches are sometimes used to provide a distribution of reserve estimates with three confidence levels (P10, P50, and P90) and a corresponding 80% confidence interval to quantify uncertainties. Our investigation indicates that uncertainty is commonly underestimated in practice when using traditional statistical analyses. The challenge in probabilistic reserve estimation is not only how to appropriately characterize probabilistic properties of complex production data sets, but also how to determine and then improve the reliability of the uncertainty quantifications. In this paper, we present an advanced technique for the probabilistic quantification of reserve estimates using decline curve analysis. We examine the reliability of the uncertainty quantification of reserve estimates by analyzing actual oil and gas wells that have produced to near-abandonment conditions, and also show how uncertainty in reserve estimates changes with time as more data become available. We demonstrate that our method provides a more reliable probabilistic reserve estimation than other methods proposed in the literature. These results have important impacts on economic risk analysis and on reservoir management.

Entrepreneurial Networking During Early Stages of Opportunity Exploitation: Agency of Novice and Experienced New Venture Leaders

2019 ◽  
Vol 44 (4) ◽  
pp. 671-699 ◽  
Author(s):  
Congcong Zheng ◽  
Mujtaba Ahsan ◽  
Alex F. DeNoble
Keyword(s):  
Qualitative Methodology ◽  
Early Stage ◽  
Three Dimensions ◽  
Time Orientation ◽  
New Venture ◽  
Short Term ◽  
Opportunity Exploitation ◽  
Early Stages ◽  
Prior Experiences

We examine how the prior experiences of new venture leaders (NVLs) affect networking behaviors during the early stages of opportunity exploitation. We argue that lack of prior experience increases the unknowns that NVLs face when pursuing opportunity exploitation. Lack of technical experience increases technical unknowns, whereas lack of startup experience increases startup unknowns. Using a qualitative methodology, we investigate 22 NVLs and find that they differ on three dimensions: networking time orientation (short-term vs. long-term), desired benefits (operational vs. symbolic), and networking actions (deepening vs. broadening). We find that novice NVLs, those who lack technical or startup experience, tend to utilize short-term orientation, engage in network-deepening actions, and seek operational benefits from their networks to mitigate technical and startup unknowns. In contrast , dual-experienced NVLs, those with technical and startup experience, are guided by long-term orientations, network-broadening actions, and a focus on symbolic benefits. We also find that technical and startup veterans exhibit a combination of those behaviors. We contribute to the literature by posing a set of three propositions depicting differences in NVL networking behaviors based on differences in startup and/or technical experiences. This study, thus, highlights the influence of NVL experience on early-stage networks.

Geothermal reservoir monitoring with a combination of absolute and relative gravimetry

Geophysics ◽  
2008 ◽  
Vol 73 (6) ◽  
pp. WA37-WA47 ◽  
Author(s):  
Mituhiko Sugihara ◽  
Tsuneo Ishido
Keyword(s):  
History Matching ◽  
Observation Interval ◽  
Time Lapse ◽  
Gravity Measurement ◽  
Absolute Gravity ◽  
Short Term ◽  
Well Production ◽  
Gravity Measurements ◽  
Central Production

Microgravity monitoring is a valuable tool for mapping the redistribution of subsurface mass and for assessing changes in fluid recharge from reservoir boundaries associated with geothermal exploitation. To further the development of a high-precision absolute/relative hybrid gravity-measurement technique, we conducted measurements using an absolute gravimeter in two geothermal fields in Japan. The absolute gravity measurements were performed in the central production areas to directly measure gravity changes caused by fluid withdrawal. We succeeded in measuring long-term trends within an accuracy of a few microgals in the Okuaizu and Ogiri fields, which have been producing electricity for several years. Absolute measurements in the center of the field provide reliable and local reference datum anchor points for more widely distributed relative gravity measurements. In the Ogiri field, we carried out time-lapse hybrid measurements with this combination of absolute and relative gravimetry and delineated the spatial distributions of long- and short-term changes. The long-term changes are relatively small, considering the four-year observation interval. This suggests a near balance between the mass withdrawal rate from wells and mass recharge from peripheral regions. The apparent balance is reproduced fairly well by a preliminary numerical reservoir simulation study. The observed long- and short-term changes are thought to be useful constraints for planned history-matching studies based on refined reservoir models with greater spatial resolution that incorporate detailed well-by-well production histories.

Fracture-Related Diagenesis May Impact Conductivity

SPE Journal ◽  
2007 ◽  
Vol 12 (03) ◽  
pp. 272-281 ◽  
Author(s):  
Jim Dean Weaver ◽  
Mark Parker ◽  
Diederik W. van Batenburg ◽  
Philip Duke Nguyen
Keyword(s):  
Field Study ◽  
Oil And Gas ◽  
Fractured Rock ◽  
Close Packing ◽  
Gas Production ◽  
Long Term Results ◽  
Hydraulic Fractures ◽  
Rapid Loss ◽  
Decline Rate

Summary Rapid loss of fracture conductivity after hydraulic fracture stimulation has often been attributed to the migration of formation fines into the proppant pack or the generation of fines derived from proppant crushing. Generation of crystalline and amorphous porosity-filling minerals can occur within the proppant pack because of chemical compositional differences between the proppant and the formation, and the compaction of the proppant bed because of proppant pressure solution reactions. Findings presented in this paper suggest that diagenesis-type reactions that can occur between proppant and freshly fractured rock surfaces can lead to rapid loss of proppant-pack porosity and loss of conductivity. Introduction Lehman et al. (2003) reported that the use of surface-modification agents (SMA) to coat proppants used in propping hydraulic fractures resulted in sustained and more uniform production from wells. Fig. 1, taken from that publication, shows the production decline curves from some of their data, and it does appear to show a significant change in decline rate compared to the use of untreated proppant. This SMA was described as a nonhardening resin that is insoluble in water and oil. It is supplied in a solvent that is quickly extracted once it is introduced to aqueous-based frac fluids, leaving a tacky, hydrophobic coating on the proppant. Initial use of this type of SMA treatment (Dewprashad et al. 1999; Nguyen et al. 1998a, b) was promoted as a method to increase the conductivity of proppant owing to its capability to prevent close packing of the proppant, which can result in increased porosity and permeability of the pack, by rendering the proppant surface tacky. Subsequent studies indicated that its use provided proppant-pack protection from fines infiltration and migration. This mechanism has been employed to explain the observations that sustained production results from the use of SMA on proppants. This is further substantiated by long-term results obtained in a single field study known for fines production problems. That both mechanisms are active has been well established through laboratory studies, but they alone do not completely explain the reduction in production decline rate as reported. A field study of SMA-treated proppant was reported to the Arkansas Oil and Gas Commission 2004 CBM Workshop that disclosed long-term results on gas production. These were CBM wells in the San Juan basin that typically required refracturing each year to produce at an economical rate. With the SMA-treated proppant, no refracs have been required, and as shown in Fig. 2, production has remained essentially constant for 5 to 6 years. This longevity was initially attributed to prevention of fines invasion into the proppant pack; however, it is possible that there are additional mechanisms operational.

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.

Examining the Impact of Hydrocarbon Drainage on Completion and In-Fill Drilling Strategies in Unconventional Reservoirs

2015 ◽  
Author(s):  
Karthik Srinivasan ◽  
Midowa Gbededo ◽  
Hongxue Hue ◽  
Jayanth Krishnamurthy ◽  
Veronica Gonzales
Keyword(s):  
Stress Distribution ◽  
History Matching ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Production Model ◽  
Hydraulic Fractures ◽  
Pressure Depletion ◽  
Asymmetric Stress ◽  
The Impact

Abstract Evaluating the effects of asymmetric stress distribution around a lateral can greatly help optimize completion techniques and overall production from in-fill horizontal wells in unconventional shale and tight reservoirs. Several factors affect long-term production from in-fill drilled wells including but not limited to pressure depletion from produced wells, change of effective stresses in the depleted formation and interference between hydraulic fractures when the new in-fill wells are drilled, stimulated and brought into production. The study addresses a variety of key challenges that the unconventional oil and gas industry is looking to understand. These include understanding: How the presence of a depleted wellbore affects hydraulic fracture propagation from a nearby newly drilled wellHow refracturing considerations in a producing well are affected by hydrocarbon drainage and modified stress contrastsHow fracturing/refracturing pumping designs and volumes should be optimized to address the challenges surrounding the wellbore Under circumstances mentioned above, pressure distribution around the wellbore from hydrocarbon drainage was estimated by history matching production data over a certain period of time. Then the impact of various types of fracturing treatments on pressure depletion profiles from offset wells was studied using a fully numerical fracture simulator that is capable of handling asymmetric stress distribution around the lateral. Fracture geometries from this study were either asymmetric due to depletion on only one side of the lateral or longer due to increased stress contrast. These fracture geometries were fed to a production model to forecast long-term production from in-fill wells and study drainage patterns over time. Understanding these challenges provided a sub-surface perspective of how completion techniques should be optimized to get maximum hydrocarbon recovery from reservoirs consisting of laterals that have already been on production.

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.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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