Reservoir Monitoring | Directorate General of Hydrocarbons (DGH)

 

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Reservoir Monitoring

 

Reservoir Group

 

Review of Format-A:

Group of DGH examines discovery notification (Format-A) reported by different operators for their new discovery before public disclosure. Reservoir Group examines whether the discovery is worth for consideration in light of produced hydrocarbons on the surface and its quantity along with other reservoir parameters determined for the fields/blocks operated under PSC regimes and NOCs

 

Review of Format-B:

Reservoir Group examines and certifies potential commercial interest of the discovery disclosed by the operators subsequent to the discovery notification w.r.t quantity of hydrocarbon flow (rate) against reservoir pressure drop and its sustainability through results of different types of flow measurements like MDT, DST, conventional testing, influx study, deliverability and AOFP of oil and gas etc. along with different types of reservoir studies as performed in accordance with industry practices.

 

Review of DOC:

It is one of the crucial documents submitted by the operator that is evaluated by Reservoir Group. This is a documentation of overall initial appraisal of the discovery area w.r.t its potential, sustainability and commerciality. The dynamic model prepared by the operator is validated for all the input data like pressure, PVT, permeability, relative permeability, productivity indices, faults, contacts, associated drive mechanisms, different fluid in-place regions and assigned production rates of different wells in the model with actual field test data or laboratory generated data. If some discrepancy/differences in data inputs are observed, cross queries are made with the operators for justification. Further, all the output data from the model are validated with respect to well-wise/sector-wise/sand-wise in-place volumes, well-wise/sand-wise/block-wise production profile generation and optimization of number of producers/injectors for optimized EUR. Production profile is either validated or made afresh if required for future years and vetted so that commerciality can be evaluated by concerned finance department in terms of revenue generation.

 

Review of FDP/RFDP:

Operator constructs static and dynamic simulation model of the appraised area to firm-up a future development strategy and to make economic decisions on entire investment proposal with the help of all the reservoir parameters acquired through different tests since discovery to end of appraisal period. A future production profile is made to exploit the trapped reserves through certain number of wells as decided by the operator. Before approving such proposals where each and every well is cost intensive irrespective of onshore or offshore area, Reservoir Group of DGH examines all the reservoir and fluid related parameters used to construct the dynamic model by operators with respect to the data acquired through actual tests performed or laboratory generated data. If found anomalous/spurious cross queries are made to avoid any future confusions and many a time these parameters are generated at DGH itself using different reservoir engineering tools like MBAL, PAN SYSTEM and reservoir simulators like ECLIPSE using test data points empirically. Many a time water injection/EOR schemes are also employed to enhance the oil recovery in FDP proposal itself by the operator. Production profiles are examined and vetted for best possible realization with optimum number of producers/injectors required for maximizing EUR. Maximization of revenue indirectly by optimization of well inputs for future development of a reservoir is one of the sole objectives of Reservoir Group at DGH. In order to keep pace with the latest technological advancement in preparation of these FDPs and DOCs vis-a-vis their tough evaluation procedure, DGH is upbeat in procuring more reservoir engineering software in near future.

 

In order to enhance oil/gas production from a field, mid-course corrections are brought forward to DGH by the operators in the form of RFDPs with some additional inputs in terms of infill producers/injectors in accordance with suitable injection pattern arrived at through history matched dynamic model. Reservoir Group validates the history matched dynamic model in terms of observed (actual) pressure-production history with those of dynamic model and examines the suitability of the additional producers/injectors as proposed by the operator to achieve incremental oil gain over and above the previous ongoing development scheme through implementation of proposed RFDP. RFDP submitted by the operator may also address the changes/surprises encountered with respect to the initial development plan and thereby incorporating the revised development plan for modified EUR based on the actual field performance as on date.

 

Review of Monthly/Quarterly Performance of fields:

As per PSC, operators use to send monthly or quarterly progress reports of hydrocarbon production of respective producing fields under their custody. Reservoir Group of DGH examines these reports in terms of well wise production behavior of different fluid phases and pressure behaviors and compares with planned production targets. If fields are under pressure maintenance/EOR, they are monitored continuously along with monitoring of desired reservoir health maintained. After analysis of these reports monthly/ quarterly or w.r.t legacy data, if available at DGH, suggestions are conveyed to the operators for any deviation in production targets, well performance, sick well revival, water injection redistribution, IOR-EOR implementation and mid-course correction to be adopted for maximizing recovery from their fields as a continuous process of reservoir surveillance. 

 

Maintenance of Reservoir Data

Reservoir Group of DGH devised a general format for importing well-wise/reservoir-wise, pressure, production, water/gas injection and Pressure Build-up data from different operators under NELP or PSC regimes. These data when made available by the operators on request are stored and maintained after proper scrutiny at DGH for future analysis and providing information to the ministry as and when sought. Data are stored and maintained either in MS EXCEL or Schlumberger OFM software.

 

Evaluation of Development well Proposals

Apart from FDP, many a time development well drilling/ side tracking/ substitute well drilling proposals are sent to DGH for approval. Reservoir Group of DGH examines such reports for suitability and merit and passes judgment for approval or rejection of such proposals after examining the performance of nearby wells based on their pressure-production behavior.

 

Evaluation of Proposals for Grant/ Extension of PML

On the basis of exploitation proposal or on better performance of the existing wells, NOCs use to seek approval for grant or extension of PML. These proposals are reviewed from reservoir point of view for proper justification and if associated with production profiles these profiles are vetted after validating inputs suggested and examining the performance of existing wells along with associated reserves under exploitation.

 

Review of Annual WP&B

Budget allocation under different reservoir engineering analysis heads are examined for their actual requirement and proper utilization. Pressure build-up/draw down/RLT/bean study/pressure gradient surveys, tracer surveys and their interpretation, PVT sample collections and their analysis, reservoir simulation study etc constitute the parts of technical studies which need to be seen from reservoir perspectives.

 

Review of Audited Accounts

Reservoir Group cross examines fund allocated under different reservoir engineering heads during annual WP&B and actual utilization in terms of studies carried out as planned.

 

Review of Third party Audited Reserves

Under directives from DGH, operators used to assign third party auditors for review of the reserves under their respective blocks or field. After audit by third party consultants interim/ final reports are sent to DGH for review/ acceptability of the figures arrived at and different process or logics adopted for estimation/ re-estimation of these reserves. Reservoir engineers at DGH verify these processes as per PRMS guidelines and examine analytical methods adopted.

 

Witnessing Calibration of CTM, HC Discovery, Well Testing

Reservoir engineers of DGH are often sent for witnessing periodic calibration of custody transfer meter at different operator’s terminal as per requirement of PSC. Moreover reservoir engineers are also deployed for witnessing hydrocarbon discovery and production testing (onshore/ offshore) at well sites of different operators and to submit report to DGH on the same.

 

Attending TCMs and MCMs

Reservoir Group participates in TCMs with the operators to clarify the doubts on different aspects of reservoir engineering in the validation process of FDP/DOC.

Reservoir Group also participates in MCMs to give justification/clarification on the stand for number of wells agreed/proposed and EUR vetted from DGH’s side.

 

Assisting Ministry

Reservoir Group of DGH are to assist ministry of petroleum of different reservoir engineering aspects of FDP/ DOC or to help understand technical implication of different reservoir parameters like drive mechanisms, flow potential, production profile etc. and  reservoir engineering reply pertaining to Parliamentary questions