"Marginal field" was introduced to the oil and gas industry to identify those fields that have negative economic effects in its development. More specifically it is possible to define a marginal field as a field that is cost ineffective to develop with conventional oil and gas means of technology. Economic development of marginal fields in most cases requires the use of existing processes to minimize cost of finding evolving technologies in development of reserves. This paper generally evaluates the feasibility of using the enhanced oil recovery technique to improve reserves in a marginal field operation environment. A marginal heavy oil field in the offshore environment of the Niger Delta region which started production in 2011 is used as a case study to evaluate the feasibility of the use of enhanced oil recovery method to improve recovery. Due to poor mobility ratio in this heavy oil field and its associated big aquifer sizes, pockets of unrecovered oil have been left behind the water fronts and water cut has risen above 80% in most of the producing wells. Recent integrated field evaluation shows that the recovery factor is poor compared to the size of oil originally in place and this triggered the need to process subsurface assessments of developing such reserves that exist in any marginal field using enhanced oil recovery technique. This paper therefore goes through the fundamental scope of an enhanced oil recovery study process to determine the applicability of this technology in a marginal oil field.
An evaluation of potential EOR processes applicable in the marginal oil field operation of the Niger Delta region is presented. Technical feasibility, process availability, oil recovery potential, and other uncertainties and risks associated with exploitation of enhanced oil recovery technique in a marginal oil field environment are being assessed. Few Enhanced oil recovery processes, namely polymer flooding, chemical flooding and microbial EOR (MEOR), are considered for possible application in this marginal oil field. The objective of the screening study is to evaluate and rank the EOR options and also select the most attractive method that will have to be further chased to a pilot test stage. Emphasis is strictly on a technical assessment of the incremental oil potential of each of the EOR methods and also identification of critical operational and logistical components of the entire process for their implementation in the offshore operating environment. Recoverable volumes associated with EOR may be significant, but key project development and implementation challenges and extra cost elements must be considered in any EOR forecast for an effective EOR process ranking. Some of these concerns (e.g. Polymer/chemical supply, facilities requirements, and the impact of EOR on reservoir performance and wellbore integrity) may be significant enough to eliminate a method from being considered further and at that point the best EOR option that requires minimal cost exposure for achieving the best recoverable shall be considered. Moreso, there is consideration of the quantity and quality of laboratory data that should support the viability of each EOR process being considered. This paper narrates the state of technical readiness for field implementation of each EOR method and identifies remaining work required to progress EOR process in this marginal oil field.
Optimizing oil production with facility constraints has become a challenge to most E&P companies even as they pursue sustainable resources. The innovative gas lift technique overcomes this challenge. The conventional gas lift well system has long been in use, but the design most times is limited by gas availability and pressure which limits the depth of gas lift injection for improved production rates. This challenge may not be evident in matured producing fields with gas compressors installed with available non-associated gas source wells, but truly such challenges arise in new fields especially owned by indigenous companies where much uncertainties at an early field life unavoidably allows you to be more stringent in expenditures towards development of a field gas lift project. A new gas lift concept was developed and studied in Field A in an offshore field of the Niger delta in the absence of gas compressors. This design has been proven to be suitable because it was used to bring four closed wells online even when those wells were removed from the company annual forecast. The original design consists of a minimum of two unloading valves and an orifice at a deeper depth, but because of the absence of scrubbers and gas compressors in the facility, pressure depletion in the reservoirs caused four flowing wells to be closed. The new design then sets dummy at shallow mandrels and uses a modified size of orifice to optimize available pressure and gas required to open the closed wells and still sustain other gas lifted wells connected to the same gas lift manifold. This campaign resulted to an additional 7000Bopd which is the primary discussion of this paper.
"Marginal field" was introduced to the oil and gas industry to identify those fields that have negative economic effects in its development. More specifically it is possible to define a marginal field as a field that is cost ineffective to develop with conventional oil and gas means of technology. Economic development of marginal fields in most cases requires the use of existing processes to minimize cost of finding evolving technologies in development of reserves. This paper generally evaluates the feasibility of using the enhanced oil recovery technique to improve reserves in a marginal field operating environment. A marginal heavy oil field in the offshore environment of the Niger Delta region which started production in 2011 is used as a case study to evaluate the feasibility of the use of enhanced oil recovery method to improve recovery. Due to poor mobility ratio in this heavy oil field and its associated big aquifer sizes, pockets of unrecovered oil have been left behind the water fronts and water cut has risen above 80% in most of the producing wells. Recent integrated field evaluation shows that the recovery factor is poor compared to the size of oil originally in place and this triggered the need to process subsurface assessments of developing such reserves that exist in any marginal field using enhanced oil recovery technique. This paper therefore goes through the fundamental scope of an enhanced oil recovery study process to determine the applicability of this technology in a marginal oil field.
Inflow control devices (ICD) have been used to balance flux around completions and also delay break-through of unwanted water into completions. Inflow-control devices (ICDs) were provided to curtail water production from heterogenous reservoirs with strong aquifer systems and/or supported with water injection. The model for the ICD consists of pressure-drop equations from the reservoir, through the screen, the flow conduit, the ICD nozzle, and into the production tubing, along with pressure drop through the lower-completion system. This additional pressure drop does not contribute to additional fluid inflow into the wellbore and this is seen to be an impairment to the productivity of horizontal wells. Pressure losses from horizontal wellbores which do not contribute to increased production is seen as skin and consequently, a new equation was derived to estimate skin due to ICD in horizontal completions. In this paper, a horizontal well equipped with inflow control device which was drilled in one of the off-shore fields of the Niger Delta region was used as a case study in evaluating the performance of an ICD completion. The new equation was used to estimate the skin due to ICD of this completion and the result obtained is compared with the skin obtained using pressure transient analysis and the results obtained from both approach are similar. This paper shares how the new equation was used to estimate skin due to ICD and the result comparison with that of a pressure transient analysis.
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