The design of geological exploration with side track drilling

The paper discusses the method of well reconstruction using sidetracks drilling as a method for searching prospective formations in Perm region. At the moment, there are small-size reservoirs of less than 100 thousand tonnes of resources included in located and prepared formations. Drilling of the reservoirs is unprofitable. Drilling a sidetrack from wells located near promising reservoirs can be more economical way to solve the problem. Drilling of sidetracks has become one of the most investment-attractive technologies aimed at stabilizing and further increasing oil production from fields being developed. This method is used to intensify the system of field development, increase the rate of oil extraction from productive formations and actually replaces the compaction of the well grid. Appropriate technologies help to save a well as well as construction and development costs. In presence of candidate wells, including plugged and abandoned one, located near promising structures, it becomes important to search for them using sidetrack drilling as a method of geological exploration. The paper describes the technology of side tracks construction and presents the algorithm of works designed. Well stock of LUKOIL-PERM LLC and geological structure of promising objects were analyzed. The technical possibility of well reconstruction by sidetracking was considered. Criteria for candidate wells and “window” kickoff intervals to be selected are defined. Calculation of profiles of second well bores for recommended wells was made, various aspects related to their construction were worked out. As a result of the work it was proposed to include these activities in the geological exploration program of LUKOIL-PERM LLC. Results of the work have practical significance and can be used in production activities of oil and gas companies

Scientific justification of the perforation methods for Famennian deposits in the southeast of the Perm Region based on geomechanical modelling

The article presents the results of analysing geological structure of the Famennian deposits (Devonian) in the Perm Region. Numerical modelling of the distribution of inhomogeneous stress field near the well was performed for the two considered types of perforation. With regard for the geometry of the forming perforation channels, numerical finite element models of near-wellbore zones were created considering slotted and cumulative perforation. It is ascertained that in the course of slotted perforation, conditions are created for a significant restoration of effective stresses and, as a result, restoration of reservoir rock permeability. Stress recovery area lies near the well within a radius equal to the length of the slots, and depends on the drawdown, with its increase, the area decreases. From the assessment of failure areas, it was found that in case of slotted perforation, the reservoir in near-wellbore zone remains stable, and failure zones can appear only at drawdowns of 10 MPa and more. The opposite situation was recorded for cumulative perforation; failure zones near the holes appear even at a drawdown of 2 MPa. In general, the analysis of results of numerical simulation of the stress state for two simulated types of perforation suggests that slotted perforation is more efficient than cumulative perforation. At the same time, the final conclusion could be drawn after determining the patterns of changes in permeability of the considered rocks under the influence of changing effective stresses and performing calculations of well flow rates after making the considered types of perforation channels