Geological and hydrodynamic modeling
One of the necessary conditions for effective drilling of horizontal wells (HW), sidetrack wells (SW) and sidetrack horizontal wells (SHW) is a careful planning of wells using geological and hydrodynamic models. A detailed three-dimensional geological model allows predicting the reservoir permeability and porosity properties in the inter-well space, designing the well path, increasing the effective length of the horizontal portion while drilling and minimizing the geological risks.
A qualitative hydrodynamic model (HDM) allows analyzing the state of workings of the deposit project formation. HDM allows you to determine the remaining reserves, no flow areas, the most productive layers in the geological section that are undeveloped by current wells, as well as the lateral location of the candidate well path considering the history of the surrounding wells production and the current front of injected water. In addition, a geological and hydrodynamic model allows you to choose the best opening and perforation intervals, forecast a candidate well production and thus assess the cost effectiveness of drilling.
Specialists of "Geonavigatsionnyye Tekhnologii" will carried out variety of work on the geological and hydrodynamic modeling of the deposit area (a sector model).
A short description of work phases on geological and hydrodynamic modeling:
- Detailed correlation schemes that allow determining the prognosis of the project drilling section are compiled. Correlation circuits are also required for binding the well formation to the formation drill log while drilling.
- Based on the correlation of wells a prognosis geological drill log is formed with determining all the layers, both collectors and shale barriers.
- On the geological drill log the permeability and the initial oil saturation is distributed. To determine the permeability, the wells geophysical data is used and also the hydrodynamic studies and core analysis results (if any).
- Hydrodynamic modeling and history matching are carried out based on wells actual data (producers and injectors), and information on the workover operations performed.
- No flow areas and non-developed by the current wells layers are determined.
- The well is projected (SW, HW or SHW) on the prognosis drill logs passing the most favorable permeability and saturation areas. The prognosis production is modeled and calculated at several variants well path profile, perforation options, as well as at other workover operations (e.g. hydraulic fracturing).
- The geological objectives of the planned well, allowable tolerance deviations, the "corridor" of target in the well path (for SW and SHW) are defined on the basis of geological and hydrodynamic models.
- For SW and SHW the recommendations on the need for drilling a pilot hole, geophysical surveys while drilling for successful well drilling into geological target are made.
The results of work
The result is a geological and hydrodynamic model (also delivered to the customer), a geological substantiating on drilling (SW, HW or SHW), which contains the following data:
- General information on the project well (the borehole number, bush, rotary table altitude , coordinates the mouth)
- Target object (reservoir, layer);
- Type of project wells (SW, HW, SHW) and the horizontal length (for SW , SHW);
- Geological objectives coordinates, allowable tolerance deviations, the "corridor" of target in the well path (for SW and SHW);
- Project candidate well path;
- Tables of expected reservoir pressures, temperature, lithology, saturation, oil-water contact along the borehole; a summary of the possible complications.
- Recommendations and description of the main risks.
- Results of geological modeling:
- geological-field characteristics of the area of the project well drilling
- Structural maps of top of target zone and target collector with designating location of project wells.
- Justification of permeability project drilling area.
- Maps of average porosity and permeability in the area;
- Geological sections along the profile of the project wells with lithology, porosity and permeability;
- Seismic sections in the area ( if any);
- Definition of zones and intervals with AHFP/ ALFP (if any);
- Recommendations (justification) on the need for drilling a pilot hole ( for SW and SHW);
- Geological section along the project well path with determined well and the "corridor" objectives.
- Plans of detailed correlation of the surrounding wells.
- Hydrodynamic modeling results:
- Results of hydrodynamic model adaptation (fluid flow rate, oil flow rate, water cut, BHP, gas factor, cumulative production of oil and liquids);
- Justification of the remaining recoverable reserves in the project area of drilling;
- The map of initial and current oil-saturated thickness;
- Cuts initial and ongoing formation of saturation in the deposit project area;
- The map of current reservoir pressures;
- Justification of project well location (the horizontal wellbore length for SW and SHW), BHP.
- The project well production prognosis ( liquid flow rate, oil rate, water cut, BHP, BHP, gas factor, cumulative production of oil and liquids);
- Schematic structure of a wellы
Upon completion of drilling after the well launching a comparative analysis of the actual parameters of the well and the results of calculation are analyzed. In case of discrepancies between the calculated and actual parameters, a detailed analysis of the causes is done, the adjustments in the calculation are made, the recommendations for further work in the area are made.