Research On Single Well Production Decline Law For JP₁,JP₂ Gas Reservoir In Xinchang Gas Field

The analysis of production decline is that seeking the law of production changes when oil and gas field (wells) went into the decline stage, and predicting future production. By The law of production decline deep understanding of the impact of the main factors of production decline, and further take effective measures to slow the production decline to increase ultimate recovery, so that scientific and rational exploitation. The law of production decline oil and gas fields have been studied hundred years abroad, first of all, R. Aronld and R. Anderson proposed the concept of production decline firstly, and given the mathematical method of calculating decline curves. Then, Arps classified on the law of production decline which based on decreasing ratio, and given output-time equation and output-cumulative production equation, to study the law of diminishing the level rose to quantify. Finally, many foreign scholars have done a lot in-depth study on the law of diminishing, for example, Fetkovich the first time proposed that modern methods of production decline curve, Palacio and Blasingame proposed the equivalent liquid decline curve analysis, later Agarwal and Gardner proposed A-G production decline analysis. In short, the foreign has a fairly mature theory method, and has made a good effect in practical application. In domestic the study of decline of production started late, mainly aimed at decreasing the type and description of research on the decline equation, but does not exceed the Arps decline of the theoretical framework generally. Also a variety of methods and means used, including expansion of Arps method, standard plate method, curve fitting, optimization approach, numerical simulation, etc. In short, the analysis of reservoir decline more, but for the gas reservoirs, particularly low permeability tight gas reservoirs of the law of diminishing relatively small.Based on the results of a comprehensive domestic and international research analysis, the A-B-F model of production decline has been taken out. The model is based on Arps traditional production decline model, the Blasingame modern production decline curve analysis method and Fetkovich standard curve fitting combination plate, Not only the production decline possesses both traditional methods and modern methods of production decline of the advantages, but also having been the character of high precision on prediction, simplicity calculation in the production forecast, obtaining formation parameters, geological reserves forecasts.Firstly according to the actual situation of the gas reservoir, all single wells are divided into six categories:no reform measures high-yield wells, reform measures high-yield wells, no reform measures medium-yield wells, reform measures medium-yield wells, no reform measures low-yield wells and reform measures low-yield wells; Then taking use of the model of A-B-F production decline to analysis the production decline law for each type of single well; then under the single well production decline law, combined gas reservoir geological characteristics and the development characteristics,sum up the main impact factors of JP1, JP2 gas reservoir single well production decline; the final, gas reservoir slow production decline proposed technical countermeasures is raised up. Understanding on these results will be of positive significance on JP1, JP2 gas reservoirs scientific and reasonable development.Knowledge and results of the Paper are as follows:(1) Analysis about JP1, JP2 gas reservoir data been collection, collation and of the two known these gas reservoirs are with similar geological and development characteristics:①strong heterogeneity;②initial production decline rapidly, post production decline slowly, almost no stabilization period;③small single well controlled reserves small;④gas reservoirs are with little water, well bore fluid is general;⑤poor connectivity between wells, the pressure drop is not balanced;⑥low level of recovery, quite different.(2) A-B-F production decline model used in the well production decline analysis obtains good results to the new gas field JP1, JP2 gas reservoirs. Mainly reflected in the law of single well production decline is in line with the actual situation, the formation parameters are consistent with the well test interpretation, and dynamic performance prediction is well fit with the actual yield.(3) Analysis about the law of diminishing of JP1, JP2 gas reservoir. Found by statistical JP1, JP2 single well gas reservoir is most accord with hyperbolic decline, a small number of single well exponential decline, there does not reconcile decline of the single well. Emerged the overall high-yield wells decline index is small, the production decline rapidly; low-yield wells decreasing indices is large, production decline slowly; the medium-yield wells are between with the two features.(4) On JP1, JP2 gas reservoirs and the law of comparative analysis of single well production decline, combination of reservoir geology and exploitation of dynamic characteristics to the specific analysis on the single well production decline of the main factors。These factors shown in the following areas:reform measures on the impact of production decline, gas well production water on the impact of production decline, other development factors on the production decline and the geological factors on the impact of production decline.(5) For the major factors affecting the Single well production decline of JP1, JP2 gas reservoir, the technical countermeasures to slow the development are proposed. As the JP1, JP2 gas reservoirs have the special features in the geological characteristics and development, countermeasures on the gas reservoir description, fracturing measures, gas drainage measures, well spacing, gas well production and gas recovery with speed to develop should be draw up.In short, making use of A-B-F production decline model to study the JP1, JP2 low permeability tight gas reservoirs single well production decline law, better results are obtained. It not only combines the advantage of traditional and modern production decline analysis method, but also presents high precision and simplicity calculation in yield prediction, obtaining formation parameters, geological reserves forecasts predict. So the method can be used to analyze the diminishing law of the same gas reservoirs well yield, thereby can further guide technology policy formulation and adjustment of the gas reservoir, and ultimately achieving enhanced oil recovery, increasing economic efficiency.