Inflow Performance Relationship And Application For Low Permeability-Defomed Media Reservoir

Initially, inflow performance relationship only empirically describes the interaction between average formation pressure and bottom hole flowing pressure, which is in the domain of deliverability testing. IPR equation is extensively used because of concision and utility, which is also mainly theoretical base on analysis of production performance, fluids rate forecast, lift technological design and optimization. Now, many studies exist for inflow performance relationship, but research is a few for low permeability reservoir, especially, for low permeability deformed media reservoir. Along with reserve rate of low permeability and super low permeability reservoir in unused oil initially in place is higher, it is more important to sustainable development of petroleum industry that low permeability reservoir is developed economically and effectively. Percolation feature has noticeable divergence between low permeability reservoir and middle-high permeability one. These difference mainly include that reservoir physical property is poor, filtrational resistance is bigger and filtration theory diverges Darcy's law. Especially, reservoirs of micro-fracture and fracture general have percolation feature of deformed media. Inflow performance relationship and fluids rate forecast are endowed with higher require with development of low permeability reservoir. More people follow closely tendency, namely, how to synthesizedly apply to theories to study IPR for low permeability deformed media reservoir, so to help with building a dimenisionless IPR model which can apply to three phase, such as oil gas water and whose representation is easy and consistent. Furthermore, all kinds of sensitive factors which control the effective development of reservoir are analysesed synthesizedly. Above research is important to enhancing the level and effect of development for low permeability reservoir. This paper retrievals research methods and documents about non-Darcy percolation, deformed media one and IPR for low permeability reservoir. Noteworthy research tendency are as follow:①Now, IPR equations is used in the field are multitudinous and have singular feature, but which also cause a lot of difficult, such as production evaluation, comparison and analysis of different block and field. So it is necessary that IPR equation with easy shape and wide applicability is used.②Now, research for IPR equation in low permeability reservoir is not fit for low permeability and deformed media reservoir whose physical property, especially, permeability generate bigger change with the alteration of formation pressure. Building a IPR equation suit for this reservoir is a important research direction.③Research approach of inflow performance relationship about improved well, such as acidizing and fracturing is few, which need further study.Combined with research tendency home and aboard of IPR, route and content of study are determined. Namely, at the base of strong stress sensitivity of low permeability reservoir being proved, guiding by percolation theory of deformed media and low permeability, a universal IPR equation for vertical wells is built with empirical method and corresponding equation with analytic approach is also brought forward. Then, after inflow performance relationship for horizontal wells is derived, availability of seven IPR equation for inclined wells and horizontal ones is estimated. Furthermore, above inflow performance relationship is extended to oil, gas and water three phase. Above work composes a full suite of system which is fit for production evaluation of low permeability-deformed media reservoir and can provide with theoretical foundation for the development of low permeability reservoir.During working on this paper, a lot of studies for IPR in low permeability-deformed media reservoir are carried on, integrating reservoir physics, rock mechanics, fluid mechanics, flow mechanics with exploitation theory of oil and gas field. Main results of research are as follow:①With respect to different view of scholars in stress sensitivity of low permeability reservoir, by analysising and comparing with pros and cons of capillary module and microscope network one, with the help of non-equivalent diameter capillary module which is present initially and concept of effective percentage of capillary diameter, it is found that different of microscope pore structure between low permeability reservoir and middle-high permeability one is the main reason for distinct of effective percentage of capillary diameter. This directly generates different of stress sensitivity for two kind of reservoir. Hence, the idea is proved theoretically that low permeability reservoir, especially, micro-fracture and fracture one, is more sensitive to stress.②Using core experiment results, for example, F31-13 well and L112-1 well in chunliang field, relationship of porosity and permeability vs effective stress is studied by linear, exponent, multiplexer and logarithm regression. Results indicate that four regression relationship can express the relationship of porosity and permeability vs effective stress. Choise of regression relationship shall be determined by analysising the change of formation pressure during the development of oil and gas field. Exponent relationship is usually adopted to.③On the base of discussion on regularity of porosity, permeability vs effective pressure,combined with difference to loss rate of permeability in micro-fracture and fracture reservoir and non-fractrure one,low permeability reservoir is divided into linear and non-linear media,which is also convenient with mathematical processing.④With respect to feature of low permeability reservoir, namely, reservoir physical property is poor, filtrational resistance is big and stress sensitivity is strong, at the base of non-equivalent diameter capillary module, relationship to average capillary diameter vs permeability or porosity and to start-up pressure gradient vs permeability or porosity are derived, which provides foundation with sentive factor analysis for IPR.⑤Dimensionless IPR equation of single phase and oil,gas two phase in low permeability-deformed media reservoir is derived for vertical wells with empirical method, which keep with consistence to Vogel equation in theoretical research. Furthermore, Dimensionless IPR equation of dissolved gas drive reservoir is built with analytic approach.⑥Dimensionless IPR equation of single phase and oil,gas phase in low permeability-deformed media reservoir is derived for horizontal wells and horizontal ones with multiple branch, integrating equivalent filtrational resistance method, potential overlay principle, conformal transformation and complex function. Applicability is evaluated between existed slant/horizontal IPR equation and IPR derived by this paper. Results shows that IPR built by this paper is optimal, Winggins-Russell-Jennings and Klins-Majc-herx equation are second, Fetkovich, Bendak-hlia-Aziz and Harrisone quation are worst.⑦IPR equation of array configuration fit for reservoir pressure above saturation pressure is studied by improved Petrobras method, which is extended to oil, gas and water three phase. IPR model and calculation procedure built can be suit for oil, gas and water three phase and mass reservoir pressure domain.⑧Sensitive factors which control highly effective development in low permeability reservoir are analysised by the universal IPR equation. Under the precondition of dynamic change of start-up pressure and deformed factor vs effective stress, mechanism of sensitive factors influencing highly effective development is initially discussion. Results shows that the difference between linear deformed reservoir and nonlinear one is not only the shape of IPR curve but also affection of sensitive factor in development of field. Pressure supervision and maintain of feasible pressure level is first factor to non-linear deformed reservoir.⑨The universal IPR equation is applied to dynamic analysis of wells by relationship on skin factors between stimulation wells, such as acidizing,fracturing and damaged wells, which is a supplemental to existed methods of danamic analysis for stimulation wells. The method of max production is using to predicting future IPR equation. Future inflow performance relationship for oil gas and water can be predict by modifiedPetrobras method of production or flowing pressure overlapping.⑩Resolution and certification of start-up pressure gradient in F125 well chunliang field and Z304-4 well maling field indicate that resolution of start-up pressure gradient is feasible with production data by IPR equation and results are correct. But this method requires upper accuracy to production data.