Development of low-permeability reservoirs (less than 1 mD) is carried out with intensive flooding. Injection is performed at pressure above the formation fracturing pressure that is why in almost every well a spontaneous growth of (injection) induced fractures takes place.The main problem of pressure transient analysis in a low permeability reservoir with spontaneous fracturing is a long linear regime flow observed in the log-log plot and the absence of a basis to achieve a pseudo-radial flow. To increase the accuracy of well testing in spontaneously fractured injection wells, certain field tests were developed and run. While testing, an injection well with spontaneously induced fractures was shut-in before the bottom-hole pressure went below the fracture closing pressure, then injection resumed for a short period of time, and then the well was shut-in again to record the pressure fall-off curve. The second pressure fall-off curve shows that the pseudo-radial flow developed, because the close of the part of the fracture without proppant occurred.The paper shows field examples of interference well tests exhibiting fracture growth up to 1700 m diagnosed in injection wells. Examples of successful restriction of injection well operation and application of correlation relationships of fracture closing pressure vs. formation pressure to lower water-cut in production wells with water breakthroughs are described.

Summary JSC Gazprom Neft ("the Company") launched an IT project in 2014 aimed at the optimization of comprehensive Well Intervention (WI) programs. Once created, those digital systems will bring the process to a new level of quality delivering the following results: Regulatory and procedural documents for the selection of candidate wells for WI, i.e., – HFC, ST, HST with MSHFC, and CUH have been updated for best practices, e.g., potential well conditions and WI application criteria/risks have been identified, and algorithms developed, for the calculation of flow rate potential, and WI candidate rating system has been set up. WI Program Development Standard has been updated.A web-based digital "WI Selection" system has been developed which uses cross-field databases to promptly select WI candidates based on the developed process document and to obtain well rating for WI across fields.A web-based "WI Agreement" system has been developed, which uses updated standard processes as the basis to have the WI's calculated in "WI Selection" agreed among specialists in charge, and to maintain the databases of approved WI's. The contemporary evaluation of the potential regarding WI quantity and efficiency with a field-by-field breakdown allows one to optimize the development of WI programs and focus on the most successful candidates, and thus, ensure target performance against WI Program keeping the costs down, as well as to develop an additional WI Program if relevant reserves are available.

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Field A considered in this paper is an oil field characterized by low permeability and large vertical variability of formation properties. Injection and production take place in commingled multi-layer zones of Field A. Wells are hydraulically fractured across the entire stack of the producing layers. In the injection wells, the bottomhole pressure is higher than the formation fracturing pressures causing continuing growth of fracture length. This paper discusses 60 multi-rate injection tests to determine the injection profiles in Field A. The tests consisted of continuous measurements of the bottomhole pressures for several constant injection rates. Measurements were made for three different injection periods with pressures below and above the formation fracturing pressure. Each injection period lasted until steady-state conditions were established. Layer injection rates were determined from stabilized injection profiles obtained by spinner surveys before the tests. Layer properties were determined by matching the constant injecting rates and layer pressures for multiple injection periods. Test results demonstrated that well performances in Field A could not be described by known solutions for a constant fracture length. The non-linear relationship between the steady-state pressure and injection rate indicated that continuous change in fracture geometry had to be taken into account. These tests were useful to determine individual layer injectivities, current formation pressures and fracture opening pressures of each layer. Based on the results, it is concluded that multi-layer, multi-rate injection tests are useful to monitor layer pressure distributions and effectively produce multi-layer fields. The Simultaneous Separate Injection (SSI) technology used in these tests provides the ability to control layer injection rates and maintain uniform production from multiple layers. The SSI technology also allows injecting controlled volumes simultaneously into several layers through one injection well. Comparison of the tests using the SSI technology and adjusted valves demonstrates redistribution of injection rates from a higher- permeability layer to a lower-permeability layer.

TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractMultipay fields are often considered to be developed with a single well pattern, which is justified by economical efficiency reasons. Using smart well technologies is now on the highest peak of popularity. Although, such technologies allow intelligent monitoring and control to be performed, the most effective well regimes consideration is a challenging problem by itself. Because of system restrictions (casing diameter, wellhead pressure, infrastructure capabilities), regulating flow from/to one of the branches of such well can reflect on the overall system performance. Considering this, wells regimes should be worked out to give maximum economic efficiency. After the plan is worked out, control could be performed by choking layers with undesirable water/gas production (i.e controlling BHP). Rosneft oil company operates Priobskoye field which has three productive layers (AC10, AC11, AC12) being developed. These layers are characterized with low permeability (1 to 20 mD) and different relative permeability characteristics which leads to non-uniform waterflooding and hence, difference in production watercut by layers. In order to perform monitoring and control procedures separately with each layer, it was considered to equip injection wells with special tools. A strategy of control for such wells is described in this paper. It is based on integrated study which includes NODAL analysis, watercut prediction and well tests. For injectivity curve (P,Q) characteristics (which is non-linear due to fractures development at high BHP), multi-rate tests are being performed. These tests allow obtaining non-linear injectivity characteristics to use it in NODAL analysis tool. Besides the method and case study, general recommendations are also given.