Abstract
Production enhancement and ultimate recovery improvement have given multi-branch horizontal wells the advantage over the vertical wells in many CBM marginal reservoirs. However, it is relatively very expensive to drill a muti-branch horizontal well than the vertical one, which makes difficulties for the engineers to determine an economical feasibility of drilling the multi-branch horizontal well as well as to estimate the productivity.
Through a widely literature review, an advanced non-analytical coupled CBM model has been developed in this study for predicting the flux and pressure in the CBM reservoir and multi-branch wellbore simultaneously. The gridding partition is achieved through adjusting the length of the grid to make the branch with an angle of horizontal direction just across the grid intersect point.
The coupled multi-branch CBM model is differeciated using modified IMPES method, LDU decomposition method is used for solving the formed seven point diagonal sparse matrix. Thereafter, the sensitivity analyses were performed to identify the dominant governing parameters such as gas slippage factor, threshold pressure gradient of formation model, branch angle, and branch number of muti-branch horizontal wellbore on the measurements of well deliverability.
The observation shows that gas slippage effect can enlarge gas production rate, while the threshold pressure gradient has the opposite effect. The gas production rate increases with the branch number ranging from 2-6, while decreases when the branch number reached to 8, so it is obviously not the case that the more the branch the better the flux enhancement. The gas flux reached to maximum when the branch angle is 45 degree, while minimum with 30 degree angle. Comparison of the fluid flux between vertical well, horizontal well and multibranch horizontal well was also made. Subsequently the proposed coupled model and developed program is validated by its application to Qinshui basin in Shanxi of China.
Through a widely literature review, an advanced non-analytical coupled CBM model has been developed in this study for predicting the flux and pressure in the CBM reservoir and multi-branch wellbore simultaneously. The gridding partition is achieved through adjusting the length of the grid to make the branch with an angle of horizontal direction just across the grid intersect point.
The coupled multi-branch CBM model is differeciated using modified IMPES method, LDU decomposition method is used for solving the formed seven point diagonal sparse matrix. Thereafter, the sensitivity analyses were performed to identify the dominant governing parameters such as gas slippage factor, threshold pressure gradient of formation model, branch angle, and branch number of muti-branch horizontal wellbore on the measurements of well deliverability.
The observation shows that gas slippage effect can enlarge gas production rate, while the threshold pressure gradient has the opposite effect. The gas production rate increases with the branch number ranging from 2-6, while decreases when the branch number reached to 8, so it is obviously not the case that the more the branch the better the flux enhancement. The gas flux reached to maximum when the branch angle is 45 degree, while minimum with 30 degree angle. Comparison of the fluid flux between vertical well, horizontal well and multibranch horizontal well was also made. Subsequently the proposed coupled model and developed program is validated by its application to Qinshui basin in Shanxi of China.
| Original language | English |
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| Pages | 1-13 |
| Number of pages | 13 |
| DOIs | |
| Publication status | Published - Mar 2012 |
| Event | SPE/EAGE European Unconventional Resources Conference and Exhibition - Vienna, Austria Duration: 20 Mar 2012 → 22 Mar 2012 |
Conference
| Conference | SPE/EAGE European Unconventional Resources Conference and Exhibition |
|---|---|
| Country/Territory | Austria |
| City | Vienna |
| Period | 20/03/12 → 22/03/12 |