Integrated Carbonate Clinoform Characterization Through Assisted History Matching of Wireline Formation Pressure Data, Karachaganak Field, Kazakhstan

Saduakassov, Bekzhan; Yakhiyayev, Nursultan; Uxukbayev, Gadilbek; Kismanov, Adilbek; Amangaliyev, Bagdad; Burns, L. R.; Baigazin, Khakim

doi:10.2118/172327-ms

Cited by 4 publications

(1 citation statement)

References 4 publications

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“…Tengiz and Karachaganak fields in the Pricaspian Basin). In such cases, heterogeneity in the lower slope can be important for predicting reservoir quality distribution, compartmentalisation and water encroachment (Collins et al, 2014; Saduakassov et al, 2014). Structural closures may include slope‐basinal facies within them (e.g.…”

Section: Introductionmentioning

confidence: 99%

Carbonate submarine fan deposits of the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico

Bishop

Bachtel²,

Thompson

et al. 2023

The Depositional Record

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Deepwater carbonate deposition is relatively poorly understood but an area of vigorous research in academia and industry, where these deposits are a significant component of many unconventional petroleum reservoirs. Recent studies of modern deepwater carbonates have highlighted the wide variety of depositional processes, sediment types and resultant geomorphology; however, well‐documented outcrops of ancient systems, their rock types and architecture are relatively sparse. The Mississippian Lake Valley Formation provides world‐class exposures of slope‐basinal carbonate deposits. The Tierra Blanca and Doña Ana members comprise submarine fans that are >14 to 20 km in length, >5 km wide, and exposed in strike and dip view, affording a unique opportunity to constrain the architecture, rock types and sedimentary processes. Tierra Blanca and Doña Ana sedimentation was dominated by crinoids shed from an up‐dip platform and supplemented by sediments sourced locally from Waulsortian mounds. Depositional processes include turbidity flows, debris flows and hybrid sediment‐gravity flows. The Tierra Blanca submarine fan thins towards its lateral flanks and distal fringe, where deposits become more mud‐dominated, gravelly grain‐supported flows are less common, and fewer beds have scoured bases. In proximal settings, bed tracing complemented by measured sections allow mapping of stratal surfaces and identification of stories, elements and complexes. The Tierra Blanca evolved from more unconfined to confined deposition. Point‐sourced deposition of the Tierra Blanca fan required a funnelling mechanism, likely due to bathymetry created by Waulsortian mounds or possibly a platform margin re‐entrant. Outcrop exposures illustrate that younger Doña Ana submarine fan deposits onlap onto, and compensationally stack with, the thickest portions of the antecedent Tierra Blanca fan. These outcrops illustrate both similarities and differences between carbonate and siliciclastic gravity flow deposits. Similarities include comparable deposit types, depositional processes and architecture; differences relate to hydrodynamics of carbonate grains, funnelling mechanisms for point‐sourced deposits and sequence stratigraphic forcing.

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Section: Introductionmentioning

confidence: 99%

Carbonate submarine fan deposits of the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico

Bishop

Bachtel²,

Thompson

et al. 2023

The Depositional Record

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Stochastic 2D Well Path Assessments for Naturally Fractured Carbonate Reservoirs

Wehunt

Borovykh

Narr

2016

SPE Western Regional Meeting

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This paper illustrates a practical method to incorporate geologically reasonable information and develop a simple but calibrated stochastic model that can be used to quantify some of the significant risks associated with alternative development well trajectories. The example in the paper describes a stochastic, 2D model of the naturally fractured depositional slope region of an isolated carbonate buildup with both gas-oil and oil-water fluid contacts, and illustrates using the model to evaluate the risks of rapid gas or water breakthrough in a horizontal well using observed fracture densities and well production histories to calibrate the model. The model uses sequence boundaries and geologically reasonable distributions of natural fractures, natural fracture clustering, and intraformational, slope clinoforms that define a mechanically layered sequence. Data are deterministic or stochastic, depending on their uncertainty ranges. The model uses an exponential fracture height distribution, and fracture spacing is proportional to fracture height. Natural fractures and clinoforms are distributed independently of well path considerations. Fractures are distributed between the sequence boundaries until the fracture lateral location exceeds model length. Next, the well and fracture geometry are used to determine whether fractures communicate between the well and the gas cap or the aquifer. The number of trials needed for modeling various scenarios was determined using an error minimization analysis. The model was successfully calibrated so that it reproduced observed field results for cases where the lower sequence boundary does not occur above the oil-water contact, adding confidence that the model could be used to represent the statistical impact of various alternative trajectories for future wells. Experimental design was used to determine the significant uncertainties and well path decisions. Heel and toe elevation, and number of clinoforms encountered were the only variables significant for modeling the frequency of water production. For modeling the frequency of direct well communication to the gas cap, the same variables were significant, in addition to well direction, completion length, and fracture density. The amount of fracture clustering applied in the model was also significant. For the example case, minimizing drawdown was not an effective strategy because productivity was low and would rarely lead to water-free production if any open fracture connected the well with the aquifer.

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Stochastic 2D Well-Path Assessments for Naturally Fractured Carbonate Reservoirs

Wehunt

Borovykh

Narr

2017

SPE Reservoir Evaluation &Amp; Engineering

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Summary Simple but geologically reasonable and calibrated 2D stochastic models are useful to quantify significant risks and uncertainties associated with alternative-development-well trajectories, particularly when statistical relationships can be established to help quantify those risks and uncertainties, and when the geologic features that create the risks and uncertainties are not adequately addressed within reservoir-flow models. Our example stochastic 2D model considered the naturally fractured depositional-slope region of an isolated carbonate buildup, and the model was populated with relevant features including distributions and geometric details of natural fractures, natural-fracture clustering, and intraformational slope clinoforms that define a mechanically layered sequence. The model was calibrated by use of well-production results and production-logging data so that it reproduced observed well results for cases where the lower sequence boundary does not occur above the oil/water contact (OWC), adding confidence that the model could be used to represent the statistical effect of various alternative trajectories for future wells. Experimental design (ED) was used to determine the significant uncertainties and well-path decisions. Heel and toe elevation and the number of clinoforms encountered by the well were the only significant variables for modeling the frequency of water production. For modeling the frequency of direct well communication to the gas cap, the same variables were significant, in addition to well direction, completion length, and fracture density. The amount of fracture clustering applied in the model was also significant. For our example case, changing the well-elevation profile was effective in managing gas or water risks; however, tradeoffs were evident—and quantified—in attempting to simultaneously address both risks. Minimizing drawdown was not an effective strategy because productivity was low and rarely resulted in economic water-free production if any open fracture connected the well with the aquifer.

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Integrated Carbonate Clinoform Characterization Through Assisted History Matching of Wireline Formation Pressure Data, Karachaganak Field, Kazakhstan

Cited by 4 publications

References 4 publications

Carbonate submarine fan deposits of the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico

Carbonate submarine fan deposits of the Mississippian Lake Valley Formation, Sacramento Mountains, New Mexico

Stochastic 2D Well Path Assessments for Naturally Fractured Carbonate Reservoirs

Stochastic 2D Well-Path Assessments for Naturally Fractured Carbonate Reservoirs

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