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产品展厅>>项目研发>>致密储层大规模压裂停泵压力解释技术服务

致密储层自然产能很低,只有采用压裂才能实现高效开发,但压后评价一直是世界难题。停泵压降分析,可以利用单段压后停泵压力分析评价各段的裂缝半长,指导压裂方案优化,提高压裂后产能评价的准确性。目前采用的微地震及电位测量法,不仅施工难度大,成本高,精确度也不高,而且无法获得裂缝导流能力及渗透率等产能计算的核心参数。因此,探索经济有效的压裂效果评价方法是高效开发致密油气藏的关键。

停泵压力测试数据预处理

变密度变流量的井底压力折算

压裂期间注入各种不同类型的压裂液,同时还需要加沙,井筒不同位置压裂液类型、沙浓度都不相同,这些不同类型的流体其密度、黏度等物性参数在井筒中会产生复杂的流动,导致将井口压力折算到井底压力的计算方法十分复杂,本项目根据力学质量守恒、动量守恒及井筒中能量守恒原理,建立考虑变密度、变流体物性的井筒垂直管流方程,采用龙格-库特法进行方程求解,从而确保井口压力折算到井底压力的精度,为正确进行停泵压力的解释分析提供保障。

停泵后水击压力的滤波消除

停泵产生的压力振荡,也就是水击效应,对压力及导数曲线前期存在着较大的影响。为了更好的对停泵压力数据进行分析解释,需要通过滤波处理压裂停泵后压力数据。

停泵压力数据软件解释分析

Laplace空间及物理空间中多段压裂水平井井底压力求解

多段压裂水平井停泵数据分析图版绘制

针对不同裂缝条数、不同裂缝长度及不同渗透率,获得不同的压力及导数双对数图版,由于水平井多段压裂的参数很多,我们提出按曲线参数重要性、大小顺序等分类排序法进行图版管理,这样有利于提高曲线拟合速度。

对每层压力数据进行停泵数据分析

通过分析可以获得:每条裂缝的半长、导流能力,以及SRV区域的渗透率、面积和平均压力等参数。

解释评价报告编制

我公司长期开展停泵压力理论研究及软件研发工作,攻克了变流量、变密度井筒垂直管流、水击效应的滤波算法及短时大注入量的压力反演三大技术难题,最终形成压裂停泵数据分析软件,在致密油气及页岩气中应用数百井段,并与微地震结果进行充分对比,验证软件的实用性和可靠性,并且可以利用已有数据进行分析,大大提高了经济效益。

Products>>Project Development>>Stop pump pressure interpretation technical services of dense reservoir large-scale fracturing

The natural capacity of dense reservoir is very low, only by fracturing can it be developed efficiently, but after-pressure evaluation has always been a world problem. single stage after-pressure stop pump pressure analysis can be used to evaluate the crack half-length of each stage and guide the fracturing scheme optimization, to improve the accuracy of the capacity evaluation after fracturing. At present, the micro-seismic and potential measurement methods are not only difficult to construct, high cost and low accuracy, but also cannot obtain the core parameters of capacity calculation, such as fracture diversion capacity and permeability. Therefore, exploring economical and effective fracturing evaluation method is the key to the efficient development of dense oil and gas reservoirs.

Pre-processing of stop pump pressure test data

Bottom-hole pressure conversion for variable density and flow

During fracturing, different types of fracturing fluid are injected and sand adding is also required. The viscosity, density and so on physical parameters of different types of fluid will produce complex flow in the wellbore,so that the calculation method of converting the wellhead pressure to the bottom hole pressure is very complicated. According to the principles of mechanical mass conservation, momentum conservation and energy conservation in wellbore, this project establishes the vertical pipe flow equation of wellbore considering variable density and fluid physical property, and adopts Longer-Kut method to solve the equation, so as to ensure the accuracy of the wellhead pressure converted to the bottom hole pressure, and to provide guarantee for the correct interpretation and analysis of the stop pump pressure.

Filtering elimination of water hammer pressure after stop pump

The pressure oscillation produced by stopping pump, that is, water hammer effect, has a great influence on the pressure and derivative curve in the early stage. In order to better analyze and explain the stop pump pressure data, it is necessary to process the pressure data after stop pump fracture by filtering.

Analysis of stop pump pressure data software

The bottom-hole pressure solution of multiple stage fracture horizontal well in Laplace space and physical space

Multi-stage fracturing horizontal well stop pump data analysis plate drawing

According to the number of different fractures, different fracture length and different permeability, different pressure and derivative double logarithmic plate are obtained. Because of the many parameters in horizontal well fracturing, we propose to manage the graph plate according to the importance of curve parameters, size order and so on, which is beneficial to improve the speed of curve simulation.

Stop pump data analysis for each layer of pressure data

Through the analysis, we can obtain: the half length of each fracture, the diversion capacity, and the parameters such as permeability, area and average pressure in the SRV area.

Interpretation and evaluation of report preparation

Based on the test and analysis, combine the drainage reality, the influence of different drainage methods on the seepage capacity of gas-water reservoir two-phase flow is studied. At the same time, the stress state is evaluated by using the pressure recovery well test results.

Our company has carried out the research on the theory of stop pump pressure and software for a long time, solved the three technical problems of variable flow rate, variable density wellbore vertical pipe flow, filtering algorithm of water hammer effect and pressure inversion of short-term large injection, finally formed fracturing stop pump data analysis software, applied hundreds of wells in dense oil and gas and shale gas, and compared fully with the results of micro-seismic, verified the practicability and reliability of the software, our software can use the existing data to analyze and greatly improve the economic benefit.

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