Wellman Unit CO2 Flood: Reservoir Pressure Reduction and Flooding the 
Water/Oil Transition Zone

Schechter, David S.; Grigg, R.; Guo, Boyun; Schneider, Barry

doi:10.2523/48948-ms

Cited by 3 publications

(1 citation statement)

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“…Shyeh‐Yung demonstrated that tertiary gas flood recoveries below MMP do not decrease as severely as predicted by slim‐tube tests for CO 2 . Schechter et al conducted coreflood tests and simulations to examine the possibility of optimizing the performance of the Wellman Unit in reducing CO 2 injection pressure. They found that dropping the pressure from above MMP to near MMP or below MMP did not reduce the efficiency in laboratory coreflooding.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

2014

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A simultaneous water and CO2 injection to a dead crude oil has been performed on sandstone cores to evaluate oil recovery under secondary immiscible, secondary near‐miscible, tertiary immiscible, and tertiary near‐miscible injection modes. It is demonstrated that secondary SWACO2 injection as well as tertiary flood is an effective method for oil/residual oil recovery from oil‐saturated/water flooded porous media. In near‐miscible condition, oil recovery is higher than in immiscible condition because there is another active pore‐scale production mechanism in near‐miscible injection besides volumetric displacement mechanism. In secondary near‐miscible SWACO2 injection, the ultimate oil recovery increases by increasing SWAG ratio from 0.2 to 0.4 but due to some limits, e.g., topological effects, prohibiting contact of injected gas with residual oil in pores, altering SWAG ratio from 0.4 to 0.6 showed no essential effect on ultimate oil recovery. Secondary SWACO2 injection can recover higher fraction of oil than tertiary SWACO2 injection. This higher oil recovery results from the oil being more accessible by injected gas due to less water‐shielding effects. The results of this work can be helpful to better recognition and selection of gas‐based oil recovery methods to be implemented in depleted reservoirs.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

2014

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Fundamental aspects, mechanisms and emerging possibilities of CO2 miscible flooding in enhanced oil recovery: A review

Kumar

Sampaio²,

Ojha³

et al. 2022

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109

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Near-Miscible Flooding by Production Gas Re-Injection in QHD 29-2 Offshore Oilfield

Chen

Zhang²,

Yang

et al. 2017

Day 3 Thu, October 26, 2017

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QHD 29-2 block is a newly discovered offshore oilfield of China with an average water depth of 27.6m, covering approximately 2300 km2. Waterflood is not suitable due to the characteristics of complex lithology, strong heterogeneity, small pores and throats, and low water injectivity. In addition, a wide range of CO2 content (24-90%) in the production gas that presents a difficulty for the mixed gas handling. Thus, near-miscible flooding of the production gas re-injection is proposed for the development of this reservoir. It is concluded that the loss of displacement efficiency can be compensated by the mobility improvement with the pressure decrease. Thus, oil recovery is comparative with that of miscible flooding. Also, the economic and operational costs declined to some extent because smaller gas volumes and lower compression are needed with the reduction of pressure. Slim tube test, slim tube simulation, and selected empirical formulas are used together to determine the near-miscible pressure interval under the condition of different CO2 contents (40%, 55%, 70%, 85%, 100%). On this basis, a new empirical formula was established to determine the lower and upper boundaries of near-miscible flooding. Two new points are determined as minimum near-miscible pressure (MNMP) and minimum miscible pressure (MMP), respectively. A higher MMP can be expected by this process which is consistent with the argument that some successful application of CO2 miscible flooding are actually partial miscible flooding or near-miscible flooding. Results showed that the ratio of MNMP to the newly defined MMP is about 0.8 to 0.86. In addition, for the wells QHD 29-2E-4 and QHD 29-2E-5, the lower limit of the CO2 content in the production gas to achieve near-miscible flooding are 34% and 64%, respectively. Moreover, the relative error of the new empirical correlation is less than 10% for the prediction of the pressure interval of near-miscible flooding in the targeted wells. To the best of our knowledge, this is the first time to study the potential of implementing near-miscible flooding by the production gas re-injection with varying CO2 content in an offshore reservoir of China. The results in the paper can provide a new screening criteria for both enhancing oil recovery and reducing greenhouse gas emissions for similar offshore reservoirs.

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Wellman Unit CO2 Flood: Reservoir Pressure Reduction and Flooding the Water/Oil Transition Zone

Cited by 3 publications

References 0 publications

Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

Fundamental aspects, mechanisms and emerging possibilities of CO2 miscible flooding in enhanced oil recovery: A review

Near-Miscible Flooding by Production Gas Re-Injection in QHD 29-2 Offshore Oilfield

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Wellman Unit CO2 Flood: Reservoir Pressure Reduction and Flooding the Water/Oil Transition Zone

Cited by 3 publications

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Experimental investigation of simultaneous water and CO2 (SWACO2) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

Experimental investigation of simultaneous water and CO2 (SWACO2) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

Fundamental aspects, mechanisms and emerging possibilities of CO2 miscible flooding in enhanced oil recovery: A review

Near-Miscible Flooding by Production Gas Re-Injection in QHD 29-2 Offshore Oilfield

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Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study

Experimental investigation of simultaneous water and CO₂ (SWACO₂) injection for oil recovery in immiscible and near‐miscible conditions: A comparative study